1
|
Lindberg CA, Roberson AE, Ghimire E, Hertzog JE, Boynton NR, Liu G, Schneiderman DK, Patel SN, Rowan SJ. Should I stay or should I flow? An exploration of phase-separated metallosupramolecular liquid crystal polymers. Chemistry 2025; 31:e202404672. [PMID: 40200604 PMCID: PMC12057607 DOI: 10.1002/chem.202404672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2024] [Revised: 03/16/2025] [Accepted: 03/19/2025] [Indexed: 04/10/2025]
Abstract
Dynamic liquid crystalline polymers (dLCPs) incorporate both liquid crystalline mesogens and dynamic bonds into a single polymeric material. These dual functionalities impart order-dependent thermo-responsive mechano-optical properties and enhanced reprocessability/programmability enabling their use as soft actuators, adaptive adhesives, and damping materials. While many previous works studying dynamic LCPs utilize dynamic covalent bonds, metallosupramolecular bonds provide a modular platform where a series of materials can be accessed from a single polymeric feedstock through the variation of the metal ion used. A series of dLCPs were prepared by the addition of metal salts to a telechelic 2,6-bisbenzimidazolylpyridine (Bip) ligand endcapped LCP to form metallosupramolecular liquid crystal polymers (MSLCPs). The resulting MSLCPs were found to phase separate into hard and soft phases which aids in their mechanical robustness. Variations of the metal salts used to access these materials allowed for control of the thermomechanical, viscoelastic, and adhesive properties with relaxations that can be tailored independently of the mesogenic transition. This work demonstrates that by accessing phase separation through the incorporation of metallosupramolecular moieties, highly processable yet robust MSLCP materials can be realized. This class of materials opens the door to LCPs with bulk flow behavior that can also be utilized as multi-level adhesives.
Collapse
Affiliation(s)
- Charlie A. Lindberg
- Pritzker School of Molecular EngineeringThe University of ChicagoChicagoIllinoisUSA
| | | | - Elina Ghimire
- Pritzker School of Molecular EngineeringThe University of ChicagoChicagoIllinoisUSA
| | - Jerald E. Hertzog
- Pritzker School of Molecular EngineeringThe University of ChicagoChicagoIllinoisUSA
| | - Nicholas R. Boynton
- Pritzker School of Molecular EngineeringThe University of ChicagoChicagoIllinoisUSA
| | - Guancen Liu
- Department of ChemistryThe University of ChicagoChicagoIllinoisUSA
| | | | - Shrayesh N. Patel
- Pritzker School of Molecular EngineeringThe University of ChicagoChicagoIllinoisUSA
| | - Stuart J. Rowan
- Pritzker School of Molecular EngineeringThe University of ChicagoChicagoIllinoisUSA
- Department of ChemistryThe University of ChicagoChicagoIllinoisUSA
- Chemical Science and Engineering Division and Center for Molecular EngineeringArgonne National LaboratoryLemontIllinoisUSA
| |
Collapse
|
2
|
Berrow SR, Raistrick T, Mandle RJ, Gleeson HF. Auxetic Liquid Crystal Elastomers: Overcoming Barriers to Scale-Up. ACS APPLIED POLYMER MATERIALS 2025; 7:4517-4524. [PMID: 40242050 PMCID: PMC11997952 DOI: 10.1021/acsapm.5c00212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/23/2025] [Revised: 03/14/2025] [Accepted: 03/19/2025] [Indexed: 04/18/2025]
Abstract
The observation of auxetic behavior (i.e., negative Poisson's ratio) in liquid crystal elastomers (LCEs) presents an exciting opportunity to explore application areas previously inaccessible to LCEs. Since its initial discovery, research has focused on improving understanding of the underpinning physics that drives the auxetic response, the structure-property relationships that enable the response to be tuned, and LCE properties such as the refractive index. However, the auxetic LCE materials reported to date have made use of either mechanical strain during fabrication, or unreactive 'templates' to stabilize the nematic ordering in the precursors. The latter approach provides excellent monodomain films, but there is unavoidable anisotropic shrinkage of the LCE. Both processes previously employed create complications toward manufacturing and scale-up. In this article, we report the first example of an auxetic LCE synthesized through surface alignment without the use of a nonreactive 'template' and thus without the need for a washout. The LCE includes both terminally and laterally attached mesogens, presents an auxetic threshold of 76% strain, and displays a comparable dependence of auxetic behavior on its glass transition temperature as that reported in the literature. This work presents an exciting milestone in the journey toward realizing applications for auxetic LCEs.
Collapse
Affiliation(s)
- Stuart R. Berrow
- School
of Physics and Astronomy, University of
Leeds, Leeds LS2 9JT, U.K.
| | - Thomas Raistrick
- School
of Physics and Astronomy, University of
Leeds, Leeds LS2 9JT, U.K.
| | - Richard J. Mandle
- School
of Physics and Astronomy, University of
Leeds, Leeds LS2 9JT, U.K.
- School
of Chemistry, University of Leeds, Leeds LS2 9JT, U.K.
| | - Helen F. Gleeson
- School
of Physics and Astronomy, University of
Leeds, Leeds LS2 9JT, U.K.
| |
Collapse
|
3
|
Terentjev EM. Liquid Crystal Elastomers: 30 Years After. Macromolecules 2025; 58:2792-2806. [PMID: 40160994 PMCID: PMC11948470 DOI: 10.1021/acs.macromol.4c01997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2024] [Revised: 02/19/2025] [Accepted: 02/25/2025] [Indexed: 04/02/2025]
Abstract
This is a Review that attempts to cast a look at the whole history of liquid crystal elastomers and the evolution of this field from its inception to the current state of the art. The exposition is limited by deliberately omitting several important elements of this field, such as densely cross-linked networks or smectic elastomers, focusing solely on the nematic phase of these elastomers. In this more narrow topic, we first discuss the current developments and perspectives in the materials chemistry. This is followed by three sections, each dedicated to one of the three main points of interest in the nematic liquid crystal elastomers: the reversible actuation, the soft elasticity, and the viscoelastic dynamics of nematic elastomers. In each of these directions, there have been significant developments over recent years but equally significant new avenues emerging for the research to follow.
Collapse
Affiliation(s)
- Eugene M. Terentjev
- Cavendish Laboratory, Cambridge
University, JJ Thomson
Avenue, Cambridge CB3 0HE, U.K.
| |
Collapse
|
4
|
Ohzono T, Katoh K, Uchida N. Boundaries and cross-linking densities modulate domain sizes of polydomain nematic elastomers. SOFT MATTER 2025; 21:1233-1240. [PMID: 39834152 DOI: 10.1039/d4sm01419g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2025]
Abstract
When nematic liquid crystal elastomers (LCEs) crosslinked at their isotropic phase are quenched to the nematic phase, they show polydomain patterns, in which nematic microdomains with different orientations self-organize into a three-dimensional mosaic with characteristic correlation patterns. The orientational correlation length of the domain, which is usually in the micrometer range, is believed to emerge as a result of a competition between liquid crystalline ordering and frozen network inhomogeneity. Although polydomain patterns show potentials as the basic platform for optical, memory, and mechanical devices, no study exists regarding how they are modulated by experimentally accessible parameters. Here, using confocal polarized fluorescence microscopy, we study the effects of a solid-wall or open boundary on the domain size in conjunction with effects of cross-linking density. The LCE bounded by solid glass shows reduced domain size near the boundary. In contrast, increased domain size appears at the free surface. With increasing cross-linking density, the domain size decreases, also exhibiting the boundary effects. Guided by theoretical considerations, the results are explained by a picture that the effective strength of the inhomogeneity frozen in the polymer network, i.e., the effective disorder strength, varies depending on the cross-linking density and constrained states at boundaries. The results offer the first experimental approach to global and local modulation of the polydomain pattern in nematic LCEs.
Collapse
Affiliation(s)
- Takuya Ohzono
- Research Institute for Electronics and Photonics, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8565, Japan.
| | - Kaoru Katoh
- Biomedical Research Institute, AIST, 1-1-1 Higashi, Tsukuba 305-8566, Japan
| | - Nariya Uchida
- Department of Physics, Tohoku University, Sendai 980-8578, Japan
| |
Collapse
|
5
|
Maghsoodi N, Bhattacharya K. Adhesion of a nematic elastomer cylinder. SOFT MATTER 2024; 21:39-44. [PMID: 39359131 DOI: 10.1039/d4sm00606b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/04/2024]
Abstract
Reversible dry adhesion is exploited by lizards and insects in nature, and is of interest to robotics and bio-medicine. In this paper, we use numerical simulation to study how the soft elasticity of liquid crystal elastomers can affect its adhesion and provide a technological opportunity. Liquid crystal elastomers are cross-linked elastomer networks with liquid crystal mesogens incorporated into the main or side chain. Polydomain liquid crystalline (nematic) elastomers exhibit unusual mechanical properties like soft elasticity, where the material deforms at nearly constant stress, due to the reorientation of mesogens. Our study reveals that the soft elasticity of nematic elastomers dramatically affects the interfacial stress distribution at the interface of a nematic elastomer cylinder adhered to a rigid substrate. The stress near the edge of the nematic cylinder under tensile load deviates from the singular behavior predicted for linear elastic materials, and the maximum normal stress reduces dramatically. This suggests that nematic elastomers should display extremely high, but controllable adhesion, consistent with the available experimental observations.
Collapse
Affiliation(s)
- Neda Maghsoodi
- Department of Aerospace and Mechanical Engineering, University of Southern California, Los Angeles, CA 90089, USA.
| | - Kaushik Bhattacharya
- Division of Engineering and Applied Science, California Institute of Technology, Pasadena, CA 91125, USA
| |
Collapse
|
6
|
Elmadih W, Terentjev A, Liang HL, Terentjev E. Overdamping of vibration resonances by liquid crystal elastomers. Sci Rep 2024; 14:25860. [PMID: 39468276 PMCID: PMC11519887 DOI: 10.1038/s41598-024-76952-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2024] [Accepted: 10/17/2024] [Indexed: 10/30/2024] Open
Abstract
This work aims to compare the capability of vibration attenuation by standard elastomeric polymers, and by the new anomalously damping nematic liquid crystal elastomer. We use the most mainstream materials in both categories, and design two testing platforms: the ASTM-standard constrained layer plate resonance geometry, and the attenuation of resonances in a commercial device (electric drill) where the damping polymers were inserted into the casing. In the standard plate resonance testing, we find that LCE outperforms all standard damping materials, moreover, it brings the vibrating plate into the overdamped condition, which is unique for a non-fluid dissipative system. In the attenuation of high-frequency vibrations of a device, we also found LCE dissipates these vibrations much better, although we did not find the optimal insertion configuration for the damping polymer, and did not reach overdamping.
Collapse
Affiliation(s)
- Waiel Elmadih
- Metamaterials Ltd, The Ingenuity Lab, Jubilee Campus, Nottingham, NG7 2TU, UK
| | - Andrew Terentjev
- Cambridge Smart Plastics Ltd, 18 Hurrell Road, Cambridge, CB4 3RH, UK
| | - Hsin-Ling Liang
- Cambridge Smart Plastics Ltd, 18 Hurrell Road, Cambridge, CB4 3RH, UK
| | - Eugene Terentjev
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge, CB3 0HE, UK.
| |
Collapse
|
7
|
Annapooranan R, Yeerella RH, Chambers RJ, Li C, Cai S. Soft elasticity enabled adhesion enhancement of liquid crystal elastomers on rough surfaces. Proc Natl Acad Sci U S A 2024; 121:e2412635121. [PMID: 39405355 PMCID: PMC11513982 DOI: 10.1073/pnas.2412635121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2024] [Accepted: 09/13/2024] [Indexed: 10/30/2024] Open
Abstract
The fabrication of pressure-sensitive adhesives (PSA) using liquid crystal elastomers (LCE) that are tolerant to substrate roughness is explored in this work. Traditional soft adhesives are designed by maintaining a balance between their cohesive strength and compliance. However, rough surfaces can significantly affect the adhesion strength of PSAs. Lowering the stiffness of the adhesive by reducing the cross-linking density or using additives can improve contact on rough surfaces. But this also decreases the cohesive strength and affects the overall performance of the adhesive. Additive-free LCE-based adhesives are shown to overcome these challenges due to their unique properties. Soft elasticity of LCE and low cross-link density contribute to their high compliance, while moderate cross-linking provides finite strength. The effect of contact time and substrate roughness on the adhesive performance is evaluated using probe-tack, indentation, lap shear, and static loading experiments. The unique combination of properties offered by LCE can lead to the development of roughness-tolerant adhesives, thereby broadening the application scope of PSAs.
Collapse
Affiliation(s)
- Raja Annapooranan
- Program in Materials Science and Engineering, University of California San Diego, La Jolla, CA92093
| | - Ram Hemanth Yeerella
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA92093
| | - Robert J. Chambers
- Program in Materials Science and Engineering, University of California San Diego, La Jolla, CA92093
| | - Chenghai Li
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA92093
| | - Shengqiang Cai
- Program in Materials Science and Engineering, University of California San Diego, La Jolla, CA92093
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA92093
| |
Collapse
|
8
|
Liang H, Zhang Y, He E, Yang Y, Liu Y, Xu H, Yang Z, Wang Y, Wei Y, Ji Y. "Cloth-to-Clothes-Like" Fabrication of Soft Actuators. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2400286. [PMID: 38722690 DOI: 10.1002/adma.202400286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2024] [Revised: 04/20/2024] [Indexed: 05/16/2024]
Abstract
Inspired by adaptive natural organisms and living matter, soft actuators appeal to a variety of innovative applications such as soft grippers, artificial muscles, wearable electronics, and biomedical devices. However, their fabrication is typically limited in laboratories or a few enterprises since specific instruments, strong stimuli, or specialized operation skills are inevitably involved. Here a straightforward "cloth-to-clothes-like" method to prepare soft actuators with a low threshold by combining the hysteretic behavior of liquid crystal elastomers (LCEs) with the exchange reaction of dynamic covalent bonds, is proposed. Due to the hysteretic behavior, the LCEs (resemble "cloth") effectively retain predefined shapes after stretching and releasing for extended periods. Subsequently, the samples naturally become soft actuators (resemble "clothes") via the exchange reaction at ambient temperatures. As a post-synthesis method, this strategy effectively separates the production of LCEs and soft actuators. LCEs can be mass-produced in bulk by factories or producers and stored as prepared, much like rolls of cloth. When required, these LCEs can be customized into soft actuators as needed. This strategy provides a robust, flexible, and scalable solution to engineer soft actuators, holding great promise for mass production and universal applications.
Collapse
Affiliation(s)
- Huan Liang
- The Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Yubai Zhang
- Research Institute of Petroleum Processing, Beijing, 100083, China
| | - Enjian He
- The Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Yang Yang
- Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing, 100084, China
| | - Yawen Liu
- The Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Hongtu Xu
- The Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Zhijun Yang
- The Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Yixuan Wang
- The Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Yen Wei
- The Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing, 100084, China
- Department of Chemistry, Center for Nanotechnology and Institute of Biomedical Technology, Chung-Yuan Christian University, Chung-Li, Taiwan, 32023, China
| | - Yan Ji
- The Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing, 100084, China
| |
Collapse
|
9
|
Ohzono T, Koyama E. Effects of Operating Mechanical Conditions and Polymer Networks of Nematic Elastomers on Photo-Induced Mechanical Performances. Macromol Rapid Commun 2024; 45:e2300709. [PMID: 38577749 DOI: 10.1002/marc.202300709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 03/21/2024] [Indexed: 04/06/2024]
Abstract
Photoresponsive liquid-crystalline elastomers (LCEs) are promising candidates for light-controlled soft actuators. Photoinduced stress/strain originates from the changes in mechanical properties after light irradiation. However, the correlation between the photoinduced mechanical performance and in-use conditions such as stress/strain states and polymer network properties (such as effective crosslink density and dangling chain density) remains unexplored for practical applications. Here, isometric photo-induced stress or isotonic strain is investigated at different operating strains or stresses, respectively, on LCEs with polymer network variations, produced by different amounts of solvent during polymerization. As the solvent volume increases, the moduli and photoinduced stresses decrease. However, the photo-induced strain, fracture strain, fracture stress, and viscosity increase. The optical response performance initially increases with the operating strain/stress, peaks at a higher actuation strain/stress, and then, decreases depending on the polymer network. The maximum work densities, which also depend on the operating stress, are in the range of ≈200-300 kJm-3. These findings, highlighting the significant variations in the mechanical performance with the operating stress/strain ranges and amount of solvent used in the synthesis, are critical for designing LCE-based mechanical devices.
Collapse
Affiliation(s)
- Takuya Ohzono
- Research Institute for Advanced Electronics and Photonics, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, 305-8565, Japan
| | - Emiko Koyama
- Research Institute for Advanced Electronics and Photonics, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, 305-8565, Japan
| |
Collapse
|
10
|
Kim D, Kim H, Jeon W, Kim HJ, Choi J, Kim Y, Kwon MS. Ultraviolet Light Debondable Optically Clear Adhesives for Flexible Displays through Efficient Visible-Light Curing. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2309891. [PMID: 38146993 DOI: 10.1002/adma.202309891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Revised: 12/19/2023] [Indexed: 12/27/2023]
Abstract
With growing sustainability concerns, the need for products that facilitate easy disassembly and reuse has increased. Adhesives, initially designed for bonding, now face demands for selective removal, enabling rapid assembly-disassembly and efficient maintenance across industries. This need is particularly evident in the display industry, with the rise of foldable devices necessitating specialized adhesives. A novel optically clear adhesive (OCA) is presented for foldable display, featuring a unique UV-stimulated selective removal feature. This approach incorporates benzophenone derivatives into the polymer network, facilitating rapid debonding under UV irradiation. A key feature of this method is the adept use of visible-light-driven radical polymerization for OCA film fabrication. This method shows remarkable compatibility with various monomers and exhibits orthogonal reactivity to benzophenone, rendering it ideal for large-scale production. The resultant OCA not only has high transparency and balanced elasticity, along with excellent resistance to repeated folding, but it also exhibits significantly reduced adhesion when exposed to UV irradiation. By merging this customized formulation with strategically integrated UV-responsive elements, an effective solution is offered that enhances manufacturing efficiency and product reliability in the rapidly evolving field of sustainable electronics and displays. This research additionally contributes to eco-friendly device fabrication, aligning with emerging technology demands.
Collapse
Affiliation(s)
- Daewhan Kim
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
| | - Hongdeok Kim
- Department of Mechanical Design Engineering, Hanyang University, Seoul, 04763, Republic of Korea
- Department of Mechanical Engineering, BK21 FOUR ERICA-ACE Center, Hanyang University, Ansan, 15588, Republic of Korea
| | - Woojin Jeon
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
| | - Hyun-Joong Kim
- Department of Agriculture, Forestry and Bioresources, Seoul National University, Seoul, 08826, Republic of Korea
| | - Joonmyung Choi
- Department of Mechanical Design Engineering, Hanyang University, Seoul, 04763, Republic of Korea
- Department of Mechanical Engineering, BK21 FOUR ERICA-ACE Center, Hanyang University, Ansan, 15588, Republic of Korea
| | - Youngdo Kim
- Mobile Display Module Development Team, Samsung Display Co., Ltd., Cheonan, 31086, Republic of Korea
| | - Min Sang Kwon
- Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea
| |
Collapse
|
11
|
Pranda PA, Hedegaard A, Kim H, Clapper J, Nelson E, Hines L, Hayward RC, White TJ. Directional Adhesion of Monodomain Liquid Crystalline Elastomers. ACS APPLIED MATERIALS & INTERFACES 2024; 16:6394-6402. [PMID: 38266384 DOI: 10.1021/acsami.3c16760] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2024]
Abstract
Pressure-sensitive adhesives (PSAs) are widely employed in consumer goods, health care, and commercial industry. Anisotropic adhesion of PSAs is often desirable to enable high force capacity coupled with facile release and has typically been realized through the introduction of complex surface and/or bulk microstructures while also maintaining high surface conformability. Although effective, microstructure fabrication can add cost and complexity to adhesive fabrication. Here, we explore aligned liquid crystalline elastomers (LCEs) as directional adhesives. Aligned LCEs exhibit direction-dependent stiffness, dissipation, and nonlinear deformation under load. By varying the cross-link content, we study how the bulk mechanical properties of LCEs correlate to their peel strength and peel anisotropy. We demonstrate up to a 9-fold difference in peel force measured when the LCE is peeled parallel vs perpendicular to the alignment axis. Opportunities to spatially localize adhesion are presented in a monolithic LCE patterned with different director orientations.
Collapse
Affiliation(s)
- Paula A Pranda
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | | | - Hyunki Kim
- 3M Company, Saint Paul, Minnesota 55144, United States
| | - Jason Clapper
- 3M Company, Saint Paul, Minnesota 55144, United States
| | - Eric Nelson
- 3M Company, Saint Paul, Minnesota 55144, United States
| | - Lindsey Hines
- 3M Company, Saint Paul, Minnesota 55144, United States
| | - Ryan C Hayward
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
- Materials Science and Engineering Program, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Timothy J White
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
- Materials Science and Engineering Program, University of Colorado Boulder, Boulder, Colorado 80309, United States
| |
Collapse
|
12
|
Miwa Y, Tsunoda M, Shimozaki S, Sawada R, Kutsumizu S. CO 2 switchable adhesion of ionic polydimethylsiloxane elastomers. Chem Commun (Camb) 2023; 59:14415-14418. [PMID: 37975300 DOI: 10.1039/d3cc04575g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2023]
Abstract
We have developed ionic polydimethylsiloxane elastomers that rapidly and reversibly increase their adhesion upon exposure to carbon dioxide (CO2) gas. The CO2 molecules dissolve quickly into the ionic aggregates, physically crosslinking the polymer chains and plasticizing them. The elastomer consequently becomes softer and more adhesive upon exposure to CO2.
Collapse
Affiliation(s)
- Yohei Miwa
- Department of Chemistry and Biomolecular Science, Faculty of Engineering, Gifu University, Yanagido, Gifu 501-1193, Japan.
- PRESTO, Japan Science and Technology Agency, Kawaguchi Center Building 4-1-8, Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Masatoshi Tsunoda
- Department of Chemistry and Biomolecular Science, Faculty of Engineering, Gifu University, Yanagido, Gifu 501-1193, Japan.
| | - Shoei Shimozaki
- Department of Chemistry and Biomolecular Science, Faculty of Engineering, Gifu University, Yanagido, Gifu 501-1193, Japan.
| | - Rina Sawada
- Department of Chemistry and Biomolecular Science, Faculty of Engineering, Gifu University, Yanagido, Gifu 501-1193, Japan.
| | - Shoichi Kutsumizu
- Department of Chemistry and Biomolecular Science, Faculty of Engineering, Gifu University, Yanagido, Gifu 501-1193, Japan.
| |
Collapse
|
13
|
Liu H, Tian H, Wang D, Yuan T, Zhang J, Liu G, Li X, Chen X, Wang C, Cai S, Shao J. Electrically active smart adhesive for a perching-and-takeoff robot. SCIENCE ADVANCES 2023; 9:eadj3133. [PMID: 37889978 PMCID: PMC10610914 DOI: 10.1126/sciadv.adj3133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Accepted: 09/25/2023] [Indexed: 10/29/2023]
Abstract
Perching-and-takeoff robot can effectively economize onboard power and achieve long endurance. However, dynamic perching on moving targets for a perching-and-takeoff robot is still challenging due to less autonomy to dynamically land, tremendous impact during landing, and weak contact adaptability to perching surfaces. Here, a self-sensing, impact-resistant, and contact-adaptable perching-and-takeoff robot based on all-in-one electrically active smart adhesives is proposed to reversibly perch on moving/static dry/wet surfaces and economize onboard energy. Thereinto, attachment structures with discrete pillars have contact adaptability on different dry/wet surfaces, stable adhesion, and anti-rebound; sandwich-like artificial muscles lower weight, enhance damping, simplify control, and achieve fast adhesion switching (on-off ratio approaching ∞ in several seconds); and the flexible pressure (0.204% per kilopascal)-and-deformation (force resolution, <2.5 millinewton) sensor enables the robot's autonomy. Thus, the perching-and-takeoff robot equipped with electrically active smart adhesives exhibits tremendous advantages of soft materials over their rigid counterparts and promising application prospect of dynamic perching on moving targets.
Collapse
Affiliation(s)
- Haoran Liu
- State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, No.28, Xianning West Road, Xi’an 710049, Shaanxi, P.R. China
- Frontier Institute of Science and Technology (FIST), Xi’an Jiaotong University, No.28, Xianning West Road, Xi’an 710049, Shaanxi, P.R. China
| | - Hongmiao Tian
- State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, No.28, Xianning West Road, Xi’an 710049, Shaanxi, P.R. China
| | - Duorui Wang
- State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, No.28, Xianning West Road, Xi’an 710049, Shaanxi, P.R. China
| | - Tengfei Yuan
- State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, No.28, Xianning West Road, Xi’an 710049, Shaanxi, P.R. China
| | - Jinyu Zhang
- State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, No.28, Xianning West Road, Xi’an 710049, Shaanxi, P.R. China
| | - Guifang Liu
- State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, No.28, Xianning West Road, Xi’an 710049, Shaanxi, P.R. China
| | - Xiangming Li
- State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, No.28, Xianning West Road, Xi’an 710049, Shaanxi, P.R. China
- Frontier Institute of Science and Technology (FIST), Xi’an Jiaotong University, No.28, Xianning West Road, Xi’an 710049, Shaanxi, P.R. China
| | - Xiaoliang Chen
- State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, No.28, Xianning West Road, Xi’an 710049, Shaanxi, P.R. China
- Frontier Institute of Science and Technology (FIST), Xi’an Jiaotong University, No.28, Xianning West Road, Xi’an 710049, Shaanxi, P.R. China
| | - Chunhui Wang
- State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, No.28, Xianning West Road, Xi’an 710049, Shaanxi, P.R. China
| | - Shengqiang Cai
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA 92093, USA
| | - Jinyou Shao
- State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, No.28, Xianning West Road, Xi’an 710049, Shaanxi, P.R. China
- Frontier Institute of Science and Technology (FIST), Xi’an Jiaotong University, No.28, Xianning West Road, Xi’an 710049, Shaanxi, P.R. China
| |
Collapse
|
14
|
Guo H, Saed MO, Terentjev EM. Mechanism of Pressure-Sensitive Adhesion in Nematic Elastomers. Macromolecules 2023; 56:6247-6255. [PMID: 37637306 PMCID: PMC10448750 DOI: 10.1021/acs.macromol.3c01038] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 06/25/2023] [Indexed: 08/29/2023]
Abstract
Nematic liquid crystal elastomers (LCEs) have anomalously high vibration damping, and it has been assumed that this is the cause of their anomalously high-pressure-sensitive adhesion (PSA). Here, we investigate the mechanism behind this enhanced PSA by first preparing thin adhesive tapes with LCE of varying cross-linking densities, characterizing their material and surface properties, and then studying the adhesion characteristics with a standard set of 90° peel, lap shear, and probe tack tests. The study confirms that the enhanced PSA is only present in (and due to) the nematic phase of the elastomer, and the strength of bonding takes over 24 h to fully reach its maximum value. Such a long saturation time is caused by the slow relaxation of local stress and director orientation in the nematic domains after pressing against the surface. We confirm this mechanism by showing that freshly pressed and annealed tape reaches the same maximum bonding strength on cooling, when the returning nematic order is forming in its optimal configuration in the pressed film.
Collapse
Affiliation(s)
- Hongye Guo
- Cavendish Laboratory, University
of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, U.K.
| | - Mohand O. Saed
- Cavendish Laboratory, University
of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, U.K.
| | - Eugene M. Terentjev
- Cavendish Laboratory, University
of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, U.K.
| |
Collapse
|
15
|
Zhao J, Meng F. Modeling Viscoelasticity and Dynamic Nematic Order of Exchangeable Liquid Crystal Elastomers. PHYSICAL REVIEW LETTERS 2023; 131:068101. [PMID: 37625059 DOI: 10.1103/physrevlett.131.068101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2023] [Accepted: 04/26/2023] [Indexed: 08/27/2023]
Abstract
Exchangeable liquid crystal elastomers (XLCEs), an emerging class of recyclable polymer materials, consist of liquid crystalline polymers which are dynamically crosslinked. We develop a macroscopic continuum model by incorporating the microscopic dynamic features of the cross-links, which can be utilized to understand the viscoelasticity of the materials together with the dynamic nematic order. As applications of the model, we study the rheological responses of XLCEs in three cases: stress relaxation, strain ramp, and creep compliance, where the materials show interesting rheology as an interplay between the dynamic nematic order of the mesogenic units, the elasticity from the network structure, and the dissipation due to chain exchange reactions. Not only being useful in understanding the physical mechanism underlying the fascinating characteristics of XLCEs, this work can also guide their future fabrications with desired rheological properties.
Collapse
Affiliation(s)
- Jiameng Zhao
- CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Fanlong Meng
- CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
- Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, Zhejiang 325000, China
| |
Collapse
|
16
|
Guo H, Terentjev A, Saed MO, Terentjev EM. Momentum transfer on impact damping by liquid crystalline elastomers. Sci Rep 2023; 13:10035. [PMID: 37340069 DOI: 10.1038/s41598-023-37215-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 06/18/2023] [Indexed: 06/22/2023] Open
Abstract
The effect of elastomeric damping pads, softening the collision of hard objects, is investigated comparing the reference silicone elastomer and the polydomain nematic liquid crystalline elastomer, which has a far superior internal dissipation mechanism. We specifically focus not just on the energy dissipation, but also on the momentum conservation and transfer during the collision, because the latter determines the force exerted on the target and/or the impactor-and it is the force that does the damage during the short time of an impact, while the energy might be dissipated on a much longer time scale. To better assess the momentum transfer, we compare the collision with a very heavy object and the collision with a comparable mass, when some of the impact momentum is retained in the target receding away from the collision. We also propose a method to estimate the optimal thickness of an elastomer damping pad for minimising the energy in impactor rebound. It has been found that thicker pads introduce a large elastic rebound and the optimal thickness is therefore the thinnest possible pad that does not suffer from mechanical failure. We find good agreement between our estimate of the minimal thickness of the elastomer before the puncture through occurs and the experimental observations.
Collapse
Affiliation(s)
- Hongye Guo
- Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK
| | - Andrew Terentjev
- Cambridge Smart Plastics Ltd, 18 Hurrell Road, Cambridge, CB4 3RH, UK
| | - Mohand O Saed
- Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK
- Cambridge Smart Plastics Ltd, 18 Hurrell Road, Cambridge, CB4 3RH, UK
| | | |
Collapse
|
17
|
Liu Z, Wang H, Zhou C. Synthesis and Characterization of a Liquid Crystal-Modified Polydimethylsiloxane Rubber with Mechanical Adaptability Based on Chain Extension in the Process of Crosslinking. ACS OMEGA 2022; 7:36590-36597. [PMID: 36278106 PMCID: PMC9583084 DOI: 10.1021/acsomega.2c04560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 09/16/2022] [Indexed: 06/16/2023]
Abstract
The mechanical adaptive material is a kind of functional material that can effectively dissipate energy and suppress the increase of its stress under continuous strain in a large deformation area, which are vital in artificial muscles, connection devices, soft artificial intelligence robots, and other areas. Scientists have been working to broaden the platform of the material's mechanical adaptive platform and improve its mechanical strength by specific structure design. Based on it, we expect to introduce a mechanism of energy dissipation from the molecular chain scale to further improve mechanical adaptability. We developed a liquid crystal-modified polydimethylsiloxane rubber with mechanical adaptability based on chain extension in the process of crosslinking. Results showed that liquid crystal (0.7 mol %)-modified silicone rubber can obviously dissipate energy to achieve mechanical adaptive function, and the energy dissipation ratio of polydimethylsiloxane rubber (MQ), 4-propyl-4'-vinyl-1,1'-bi(cyclohexane)-modified polydimethylsiloxane rubber (3CCV-MQ), and 4-methoxyphenyl-4-(3-butenyloxy) benzoate-modified polydimethylsiloxane rubber (MBB-MQ) gradually decreases from 30 to 24%. Excessive thiol groups of liquid crystal-modified polydimethylsiloxane react with its vinyl group to achieve the chain extension, which significantly improves the mechanical strength from 2.74 to 5.83 MPa and elongation at break from 733 to 1096%. This research offers some new insights into improving the mechanical strength of silicone rubber and is of great significance for the application of the mechanical adaptive material.
Collapse
|
18
|
Ohzono T, Koyama E. Photo-Rewritable Glaring Patterns Composed of Stripe Domains in Nematic Elastomers. Macromol Rapid Commun 2022; 43:e2200599. [PMID: 35904150 DOI: 10.1002/marc.202200599] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 07/21/2022] [Indexed: 11/08/2022]
Abstract
Dynamic ordered micropatterns in polymeric materials provide an effective approach for the on-demand tuning of optical properties toward a smart optical material. In this study, we show that glaring patterns exhibiting strong anisotropic light diffusion can be developed at specific locations in nematic liquid-crystal elastomers with light-sensitive azobenzene units. Glaring originates from the stripe domains of the nematic directors that self-organize in light-irradiated regions after a simple uniaxial stretching and releasing process without any complicated lithographic technique. The nematic order transiently reduced by the photo-induced cis azobenzene isomers unlocks entropic elasticity, which induces local uniaxial shrinkage that causes buckling of the directors forming stripe domains. The written pattern on the film is tangibly visible with the backlight owing to the difference in anisotropic light diffusion. Furthermore, this pattern can be erased by light irradiation or thermal annealing. These films can be applied to optical elements for achieving augmented luminaries, security labeling, and sign-sheeting applications. This article is protected by copyright. All rights reserved.
Collapse
Affiliation(s)
- Takuya Ohzono
- Research Institute for Advanced Electronics and Photonics, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, 305-8565, Japan
| | - Emiko Koyama
- Research Institute for Advanced Electronics and Photonics, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, 305-8565, Japan
| |
Collapse
|
19
|
Choi S, Kim B, Park S, Seo JH, Ahn SK. Slidable Cross-Linking Effect on Liquid Crystal Elastomers: Enhancement of Toughness, Shape-Memory, and Self-Healing Properties. ACS APPLIED MATERIALS & INTERFACES 2022; 14:32486-32496. [PMID: 35792581 DOI: 10.1021/acsami.2c06462] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The network structures of liquid crystal elastomers (LCEs) are crucial to impart rubbery behavior to LCEs and enable reversible actuation. Most LCEs developed to date are covalently linked, implying that the cross-links are fixed at a particular position. Herein, we report a new class of LCEs integrating polyrotaxanes (PRs) as slidable cross-links (PR-LCEs). Interestingly, the incorporation of a low loading (0.3-2.0 wt %) of the PR cross-linkers to the LCE causes a significant impact on various properties of the resulting PR-LCEs due to the pulley effect. The optimum PR loading is determined to be 0.5 wt %, at which point the toughness and damping behavior are maximized. The robust mechanical properties of the PR-LCE offers a superior actuation performance to that of the pristine LCE along with an excellent quadruple shape-memory effect. Furthermore, the incorporation of PR is useful to enhance the efficiency of shape-memory-assisted self-healing when heating above the nematic-isotropic transition.
Collapse
Affiliation(s)
- Subi Choi
- Department of Polymer Science and Engineering, Pusan National University, Busan 46241, Republic of Korea
| | - Bitgaram Kim
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Sungmin Park
- Advanced Materials Division, Korea Research Institute of Chemical Technology, Daejeon 34114, Republic of Korea
| | - Ji-Hun Seo
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Suk-Kyun Ahn
- Department of Polymer Science and Engineering, Pusan National University, Busan 46241, Republic of Korea
| |
Collapse
|
20
|
Li Y, Liu T, Ambrogi V, Rios O, Xia M, He W, Yang Z. Liquid Crystalline Elastomers Based on Click Chemistry. ACS APPLIED MATERIALS & INTERFACES 2022; 14:14842-14858. [PMID: 35319184 DOI: 10.1021/acsami.1c21096] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Liquid crystalline elastomers (LCEs) have emerged as an important class of functional materials that are suitable for a wide range of applications, such as sensors, actuators, and soft robotics. The unique properties of LCEs originate from the combination between liquid crystal and elastomeric network. The control of macroscopic liquid crystalline orientation and network structure is crucial to realizing the useful functionalities of LCEs. A variety of chemistries have been developed to fabricate LCEs, including hydrosilylation, free radical polymerization of acrylate, and polyaddition of epoxy and carboxylic acid. Over the past few years, the use of click chemistry has become a more robust and energy-efficient way to construct LCEs with desired structures. This article provides an overview of emerging LCEs based on click chemistries, including aza-Michael addition between amine and acrylate, radical-mediated thiol-ene and thiol-yne reactions, base-catalyzed thiol-acrylate and thiol-epoxy reactions, copper-catalyzed azide-alkyne cycloaddition, and Diels-Alder cycloaddition. The similarities and differences of these reactions are discussed, with particular attention focused on the strengths and limitations of each reaction for the preparation of LCEs with controlled structures and orientations. The compatibility of these reactions with the traditional and emerging processing techniques, such as surface alignment and additive manufacturing, are surveyed. Finally, the challenges and opportunities of using click chemistry for the design of LCEs with advanced functionalities and applications are discussed.
Collapse
Affiliation(s)
- Yuzhan Li
- School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Tuan Liu
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Veronica Ambrogi
- Department of Chemical, Materials and Production Engineering, University of Naples Federico II, Napoli 80125, Italy
| | - Orlando Rios
- Department of Materials Science and Engineering, The University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Min Xia
- School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Wanli He
- School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Zhou Yang
- School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| |
Collapse
|
21
|
Li K, Zan X, Tang C, Liu Z, Fan J, Qin G, Yang J, Cui W, Zhu L, Chen Q. Tough, Instant, and Repeatable Adhesion of Self-Healable Elastomers to Diverse Soft and Hard Surfaces. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2105742. [PMID: 35187853 PMCID: PMC9036032 DOI: 10.1002/advs.202105742] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 01/22/2022] [Indexed: 06/14/2023]
Abstract
Repeatability and high adhesion toughness are usually contradictory for common polymer adhesives. Repeatability requires temporary interactions between the adhesive and the substrate, while high adhesion toughness is usually achieved by permanent bonding. Integrating these two features into one adhesive system is still a daunting challenge. Here, the development of a series of viscoelastic elastomers composed of a soft and hard segment is reported, which exhibit tough, instant, yet repeatable adhesion to a variety of soft and hard surfaces. Such a combination of mutually exclusive properties is attributed to the synergy of high mobility of polymer chains and massive viscoelastic dissipation of the elastomers around the interface. By optimizing the relaxation time and mechanical dissipation, the resulting adhesives can achieve a tough yet repeatable adhesion toughness above 2000 J m-2 , superior to the best-in-class commercial adhesives. Numerous acrylate monomers are proven applicable to the preparation of such adhesives, validating the universality of the fabrication method. The application of these elastomers as adhesive and protective layers in soft electronics by virtue of their universal and tough adhesion to various soft and hard substrates is also demonstrated.
Collapse
Affiliation(s)
- Ke Li
- Wenzhou InstituteUniversity of Chinese Academy of SciencesWenzhou352001China
- School of Materials Science and EngineeringHenan Polytechnic UniversityJiaozuo454000China
| | - Xingjie Zan
- Wenzhou InstituteUniversity of Chinese Academy of SciencesWenzhou352001China
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health)Wenzhou352001China
| | - Chen Tang
- Wenzhou InstituteUniversity of Chinese Academy of SciencesWenzhou352001China
- School of Materials Science and EngineeringHenan Polytechnic UniversityJiaozuo454000China
| | - Zhuangzhuang Liu
- Wenzhou InstituteUniversity of Chinese Academy of SciencesWenzhou352001China
| | - Jianghuan Fan
- Wenzhou InstituteUniversity of Chinese Academy of SciencesWenzhou352001China
| | - Gang Qin
- School of Materials Science and EngineeringHenan Polytechnic UniversityJiaozuo454000China
| | - Jia Yang
- School of Materials Science and EngineeringHenan Polytechnic UniversityJiaozuo454000China
| | - Wei Cui
- College of Polymer Science and EngineeringState Key Laboratory of Polymer Materials EngineeringSichuan UniversityChengdu610065China
| | - Lin Zhu
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health)Wenzhou352001China
| | - Qiang Chen
- Wenzhou InstituteUniversity of Chinese Academy of SciencesWenzhou352001China
- School of Materials Science and EngineeringHenan Polytechnic UniversityJiaozuo454000China
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health)Wenzhou352001China
| |
Collapse
|
22
|
Saed M, Gablier A, Terentjev EM. Exchangeable Liquid Crystalline Elastomers and Their Applications. Chem Rev 2022; 122:4927-4945. [PMID: 33596647 PMCID: PMC8915166 DOI: 10.1021/acs.chemrev.0c01057] [Citation(s) in RCA: 67] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Indexed: 12/30/2022]
Abstract
This Review presents and discusses the current state of the art in "exchangeable liquid crystalline elastomers", that is, LCE materials utilizing dynamically cross-linked networks capable of reprocessing, reprogramming, and recycling. The focus here is on the chemistry and the specific reaction mechanisms that enable the dynamic bond exchange, of which there is a variety. We compare and contrast these different chemical mechanisms and the key properties of their resulting elastomers. In the conclusion, we discuss the most promising applications that are enabled by dynamic cross-linking and present a summary table: a library of currently available materials and their main characteristics.
Collapse
Affiliation(s)
- Mohand
O. Saed
- Cavendish Laboratory, University
of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE, U.K.
| | - Alexandra Gablier
- Cavendish Laboratory, University
of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE, U.K.
| | - Eugene M. Terentjev
- Cavendish Laboratory, University
of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE, U.K.
| |
Collapse
|
23
|
Ohzono T, Koyama E. Effects of photo-isomerizable side groups on the phase and mechanical properties of main-chain nematic elastomers. Polym Chem 2022. [DOI: 10.1039/d2py00256f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A series of main-chain nematic liquid crystal elastomers containing various photo-isomerizable side groups branching from the main chain were synthesized. The effects of the side groups on the thermal phase and mechanical properties were explored.
Collapse
Affiliation(s)
- Takuya Ohzono
- Research Institute for Advanced Electronics and Photonics, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8565, Japan
| | - Emiko Koyama
- Research Institute for Advanced Electronics and Photonics, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8565, Japan
| |
Collapse
|
24
|
Saed MO, Elmadih W, Terentjev A, Chronopoulos D, Williamson D, Terentjev EM. Impact damping and vibration attenuation in nematic liquid crystal elastomers. Nat Commun 2021; 12:6676. [PMID: 34795251 PMCID: PMC8602409 DOI: 10.1038/s41467-021-27012-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 10/22/2021] [Indexed: 11/16/2022] Open
Abstract
Nematic liquid crystal elastomers (LCE) exhibit unique mechanical properties, placing them in a category distinct from other viscoelastic systems. One of their most celebrated properties is the 'soft elasticity', leading to a wide plateau of low, nearly-constant stress upon stretching, a characteristically slow stress relaxation, enhanced surface adhesion, and other remarkable effects. The dynamic soft response of LCE to shear deformations leads to the extremely large loss behaviour with the loss factor tanδ approaching unity over a wide temperature and frequency ranges, with clear implications for damping applications. Here we investigate this effect of anomalous damping, optimising the impact and vibration geometries to reach the greatest benefits in vibration isolation and impact damping by accessing internal shear deformation modes. We compare impact energy dissipation in shaped samples and projectiles, with elastic wave transmission and resonance, finding a good correlation between the results of such diverse tests. By comparing with ordinary elastomers used for industrial damping, we demonstrate that the nematic LCE is an exceptional damping material and propose directions that should be explored for further improvements in practical damping applications.
Collapse
Affiliation(s)
- Mohand O Saed
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge, CB3 0HE, UK
- Cambridge Smart Plastics Ltd, 18 Hurrell Rd, Cambridge, CB4 3RH, UK
| | - Waiel Elmadih
- Institute for Aerospace Technology, University of Nottingham, Nottingham, NG7 2RD, UK
| | - Andrew Terentjev
- Cambridge Smart Plastics Ltd, 18 Hurrell Rd, Cambridge, CB4 3RH, UK
| | - Dimitrios Chronopoulos
- Department of Mechanical Engineering (LMSD), KU Leuven, Ghent Technology Campus, 9000, Gent, Belgium.
| | - David Williamson
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Eugene M Terentjev
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge, CB3 0HE, UK.
| |
Collapse
|
25
|
Lee TH, Han GY, Yi MB, Shin JH, Kim HJ. Photoresponsive, switchable, pressure-sensitive adhesives: influence of UV intensity and hydrocarbon chain length of low molecular weight azobenzene compounds. RSC Adv 2021; 11:37392-37402. [PMID: 35496405 PMCID: PMC9043784 DOI: 10.1039/d1ra06596c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 11/12/2021] [Indexed: 11/26/2022] Open
Abstract
Unlike traditional adhesives with a fixed adhesive force, switchable adhesives, which have an adhesive force that can be adjusted by external stimuli, are specifically designed to be released according to user demand, or to enable the transfer of fine electronic devices. Previously developed switchable adhesives have limitations such as a slow switching rate, narrow adhesion modulation range, or the lack of reusability. Thus, we fabricated switchable pressure-sensitive adhesives (PSAs) that can overcome these limitations. The adhesive force of each switchable PSA, which comprises an azobenzene-containing acrylic polymer and low molecular weight compounds, was designed to be activated/deactivated via ultraviolet (UV) and visible light irradiation. The adhesive force and UV intensity required for the switch were found to be dependent on the aliphatic chain length of the compound. The adhesive force of the SP-C10, i.e., a switchable PSA containing a azobenzene compound with an aliphatic chain of 10 hydrocarbons, increased to 3.5 N from nearly zero in response to only 30 s of low-level (25 mW cm−2) UV irradiation. Additionally, SP-C10 did not lose its adhesive force even after 30 cycles of repeated adhesion switching. The mechanism of adhesion switching influenced by UV intensity and the structure of low molecular weight azobenzene compounds are also reported. A photoresponsive switchable pressure-sensitive adhesive (PSA) was fabricated with an azobenzene-containing polymer and low molecular weight compounds. Its adhesion force was activated/deactivated rapidly by UV/visible light irradiation.![]()
Collapse
Affiliation(s)
- Tae-Hyung Lee
- Laboratory of Adhesion and Bio-Composites, Program in Environmental Materials Science, Department of Agriculture, Forestry and Bioresources, Seoul National University 1 Gwanak-ro, Gwanak-gu Seoul 08826 Republic of Korea
| | - Gi-Yeon Han
- Laboratory of Adhesion and Bio-Composites, Program in Environmental Materials Science, Department of Agriculture, Forestry and Bioresources, Seoul National University 1 Gwanak-ro, Gwanak-gu Seoul 08826 Republic of Korea
| | - Mo-Beom Yi
- Laboratory of Adhesion and Bio-Composites, Program in Environmental Materials Science, Department of Agriculture, Forestry and Bioresources, Seoul National University 1 Gwanak-ro, Gwanak-gu Seoul 08826 Republic of Korea
| | - Jae-Ho Shin
- Laboratory of Adhesion and Bio-Composites, Program in Environmental Materials Science, Department of Agriculture, Forestry and Bioresources, Seoul National University 1 Gwanak-ro, Gwanak-gu Seoul 08826 Republic of Korea
| | - Hyun-Joong Kim
- Laboratory of Adhesion and Bio-Composites, Program in Environmental Materials Science, Department of Agriculture, Forestry and Bioresources, Seoul National University 1 Gwanak-ro, Gwanak-gu Seoul 08826 Republic of Korea .,Research Institute of Agriculture and Life Sciences, Seoul National University 1 Gwanak-ro, Gwanak-gu Seoul 08826 Republic of Korea
| |
Collapse
|
26
|
Wu J, Yao S, Zhang H, Man W, Bai Z, Zhang F, Wang X, Fang D, Zhang Y. Liquid Crystal Elastomer Metamaterials with Giant Biaxial Thermal Shrinkage for Enhancing Skin Regeneration. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2106175. [PMID: 34561930 DOI: 10.1002/adma.202106175] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Indexed: 06/13/2023]
Abstract
Liquid crystal elastomers (LCEs) are a class of soft active materials of increasing interest, because of their excellent actuation and optical performances. While LCEs show biomimetic mechanical properties (e.g., elastic modulus and strength) that can be matched with those of soft biological tissues, their biointegrated applications have been rarely explored, in part, due to their high actuation temperatures (typically above 60 °C) and low biaxial actuation performances (e.g., actuation strain typically below 10%). Here, unique mechanics-guided designs and fabrication schemes of LCE metamaterials are developed that allow access to unprecedented biaxial actuation strain (-53%) and biaxial coefficient of thermal expansion (-33 125 ppm K-1 ), significantly surpassing those (e.g., -20% and -5950 ppm K-1 ) reported previously. A low-temperature synthesis method with use of optimized composition ratios enables LCE metamaterials to offer reasonably high actuation stresses/strains at a substantially reduced actuation temperature (46 °C). Such biocompatible LCE metamaterials are integrated with medical dressing to develop a breathable, shrinkable, hemostatic patch as a means of noninvasive treatment. In vivo animal experiments of skin repair with both round and cross-shaped wounds demonstrate advantages of the hemostatic patch over conventional strategies (e.g., medical dressing and suturing) in accelerating skin regeneration, while avoiding scar and keloid generation.
Collapse
Affiliation(s)
- Jun Wu
- AML, Department of Engineering Mechanics, Center for Flexible Electronics Technology, Tsinghua University, Beijing, 100084, P. R. China
| | - Shenglian Yao
- School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Hang Zhang
- AML, Department of Engineering Mechanics, Center for Flexible Electronics Technology, Tsinghua University, Beijing, 100084, P. R. China
| | - Weitao Man
- Department of Neurosurgery, Beijing Tsinghua Changgung Hospital, School of Clinical Medicine, Tsinghua University, Beijing, 102218, P. R. China
| | - Zhili Bai
- School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Fan Zhang
- AML, Department of Engineering Mechanics, Center for Flexible Electronics Technology, Tsinghua University, Beijing, 100084, P. R. China
| | - Xiumei Wang
- School of Materials Science and Engineering, Tsinghua University, Beijing, 100084, P. R. China
| | - Daining Fang
- Institute of Advanced Structure Technology, Beijing Key Laboratory of Lightweight Multi-Functional Composite Materials and Structures, Beijing Institute of Technology, Beijing, 100081, P. R. China
| | - Yihui Zhang
- AML, Department of Engineering Mechanics, Center for Flexible Electronics Technology, Tsinghua University, Beijing, 100084, P. R. China
| |
Collapse
|
27
|
Ohzono T, Minamikawa H, Koyama E, Norikane Y. Impact of Crystallites in Nematic Elastomers on Dynamic Mechanical Properties and Adhesion. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c01160] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Takuya Ohzono
- Research Institute for Advanced Electronics and Photonics, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8565, Japan
| | - Hiroyuki Minamikawa
- Interdisciplinary Research Center for Catalytic Chemistry, AIST, 1-1-1 Higashi, Tsukuba 305-8565, Japan
| | - Emiko Koyama
- Research Institute for Advanced Electronics and Photonics, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8565, Japan
| | - Yasuo Norikane
- Research Institute for Advanced Electronics and Photonics, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8565, Japan
| |
Collapse
|
28
|
Lee TH, Han GY, Yi MB, Kim HJ, Lee JH, Kim S. Rapid Photoresponsive Switchable Pressure-Sensitive Adhesive Containing Azobenzene for the Mini-Light Emitting Diode Transfer Process. ACS APPLIED MATERIALS & INTERFACES 2021; 13:43364-43373. [PMID: 34469097 DOI: 10.1021/acsami.1c11680] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Materials that can switch adhesive properties based on external stimuli are required in several industries for temporary bonding or transfer processes. Previously studied materials achieve this under restricted conditions (hydration, heat, and long switching times), and some materials have limitations related to reuse because of irreversible reactions or residue formation on substrates. Herein, a rapid photoresponsive switchable pressure-sensitive adhesive (PSA) fabricated using an acrylic polymer and an aliphatic monomer containing azobenzene is reported. The adhesion force of the proposed PSA can be switched by photoisomerizing the azobenzene moiety. The process induces the transition of surface energy and modulus of the PSA. Ultraviolet and visible light irradiation can switch the probe tack force from 200 to 4 kPa within 15-30 s. Adhesion switching is possible in a state wherein the PSA remains adhered to a substrate. Mini-LEDs are selectively transferred from the carrier PSA to a polydimethylsiloxane substrate following the process of partial adhesion switching of the PSA. The novel and switchable PSA, which exhibits a selective and repeatable adhesion switching property and high switching ratio when stimulated by light stimuli, may be potentially used to realize the mini-LED or micro-LED transfer processes.
Collapse
Affiliation(s)
- Tae-Hyung Lee
- Program in Environmental Materials Science, Department of Agriculture, Forestry, and Bioresources, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Gi-Yeon Han
- Program in Environmental Materials Science, Department of Agriculture, Forestry, and Bioresources, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Mo-Beom Yi
- Program in Environmental Materials Science, Department of Agriculture, Forestry, and Bioresources, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Hyun-Joong Kim
- Program in Environmental Materials Science, Department of Agriculture, Forestry, and Bioresources, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
- Research Institute of Agriculture and Life Sciences, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Jae-Hak Lee
- Department of Ultra-Precision Machines and Systems, Korea Institute of Machinery & Materials, 156 Gajeongbuk-Ro, Yuseong-Gu, Daejeon 34103, Republic of Korea
| | - Seungman Kim
- Department of Ultra-Precision Machines and Systems, Korea Institute of Machinery & Materials, 156 Gajeongbuk-Ro, Yuseong-Gu, Daejeon 34103, Republic of Korea
| |
Collapse
|
29
|
Wang J, Wan Y, Wang X, Xia Z. Bioinspired Smart Materials With Externally-Stimulated Switchable Adhesion. FRONTIERS IN NANOTECHNOLOGY 2021. [DOI: 10.3389/fnano.2021.667287] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Living organisms have evolved, over billions of years, to develop specialized biostructures with switchable adhesion for various purposes including climbing, perching, preying, sensing, and protecting. According to adhesion mechanisms, switchable adhesives can be divided into four categories: mechanically-based adhesion, liquid-mediated adhesion, physically-actuated adhesion and chemically-enhanced adhesion. Mimicking these biostructures could create smart materials with switchable adhesion, appealing for many engineering applications in robotics, sensors, advanced drug-delivery, protein separation, etc. Progress has been made in developing bioinspired materials with switchable adhesion modulated by external stimuli such as electrical signal, magnetic field, light, temperature, pH value, etc. This review will be focused on new advance in biomimetic design and synthesis of the materials and devices with switchable adhesion. The underlying mechanisms, design principles, and future directions are discussed for the development of high-performance smart surfaces with switchable adhesion.
Collapse
|
30
|
You R, Kang S, Lee C, Jeon J, Wie JJ, Kim TS, Yoon DK. Programmable Liquid Crystal Defect Arrays via Electric Field Modulation for Mechanically Functional Liquid Crystal Networks. ACS APPLIED MATERIALS & INTERFACES 2021; 13:36253-36261. [PMID: 34310107 DOI: 10.1021/acsami.1c04999] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The arrangement of mesogenic units determines mechanical response of the liquid crystal polymer network (LCN) film to heat. Here, we show an interesting approach to programming three-dimensional patterns of the LCN films with periodic topological defects generated by applying an electric field. The mechanical properties of three representative patterned LCN films were investigated in terms of the arrangement of mesogenic units through tensile testing. Remarkably, it was determined that LCN films showed enhanced toughness and ductility as defects increased in a given area, which is related to the elastic modulus mismatch that mitigates crack propagation. Our platform can also be used to modulate the frictional force of the patterned LCN films by varying the temperature, which can provide insight into the multiplex mechanical properties of LCN films.
Collapse
Affiliation(s)
- Ra You
- Department of Chemistry, KAIST, Daejeon 34141, Republic of Korea
| | - Sumin Kang
- Department of Mechanical Engineering, KAIST, Daejeon 34141, Republic of Korea
| | - Changjae Lee
- Department of Chemistry, KAIST, Daejeon 34141, Republic of Korea
| | - Jisoo Jeon
- Department of Polymer Science and Engineering, Inha University, Incheon 22212, Republic of Korea
- Program in Environmental and Polymer Engineering, Inha University, Incheon 22212, Republic of Korea
| | - Jeong Jae Wie
- Department of Polymer Science and Engineering, Inha University, Incheon 22212, Republic of Korea
- Program in Environmental and Polymer Engineering, Inha University, Incheon 22212, Republic of Korea
| | - Taek-Soo Kim
- Department of Mechanical Engineering, KAIST, Daejeon 34141, Republic of Korea
| | - Dong Ki Yoon
- Department of Chemistry, KAIST, Daejeon 34141, Republic of Korea
- Graduate School of Nanoscience and Technology and KAIST Institute for Nanocentury, KAIST, Daejeon 34141, Republic of Korea
| |
Collapse
|
31
|
Kondo M, Kojima D, Ootsuki N, Kawatsuki N. Photoinduced Exfoliation of a Polymeric
N
‐Benzylideneaniline Liquid‐Crystalline Composite Based on a Photoisomerization‐Triggered Phase Transition. MACROMOL CHEM PHYS 2021. [DOI: 10.1002/macp.202100097] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Mizuho Kondo
- Department of Applied Chemistry Graduate School of Engineering University of Hyogo 2167 Shosha Himeji Hyogo 671‐2280 Japan
| | - Daijoro Kojima
- Department of Applied Chemistry Graduate School of Engineering University of Hyogo 2167 Shosha Himeji Hyogo 671‐2280 Japan
| | - Naoya Ootsuki
- Technical Development Department ThreeBond Co., Ltd. Sagamihara 252‐0146 Japan
| | - Nobuhiro Kawatsuki
- Department of Applied Chemistry Graduate School of Engineering University of Hyogo 2167 Shosha Himeji Hyogo 671‐2280 Japan
| |
Collapse
|
32
|
Ohzono T, Katoh K, Terentjev EM. Microscopy of Diffuse Nematic–Isotropic Transition in Main-Chain Nematic Liquid-Crystal Elastomers. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c00356] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Takuya Ohzono
- Research Institute for Electronics and Photonics, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8565, Japan
| | - Kaoru Katoh
- Biomedical Research Institute, AIST, 1-1-1 Higashi, Tsukuba 305-8566, Japan
| | - Eugene M. Terentjev
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| |
Collapse
|
33
|
Yu X, Dong C, Zhuang W, Shi D, Dong W, Chen M, Kaneko D. Bio-Based Hotmelt Adhesives with Well-Adhesion in Water. Polymers (Basel) 2021; 13:666. [PMID: 33672307 PMCID: PMC7927086 DOI: 10.3390/polym13040666] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 02/16/2021] [Accepted: 02/18/2021] [Indexed: 12/17/2022] Open
Abstract
We suggest a simple idea of bio-based adhesives with strong adhesion even under water. The adhesives simply prepared via polycondensation of 3,4-dihydroxyhydrocinnamic acid (DHHCA) and lactic acid (LA) in one pot polymerization. Poly(DHHCA-co-LA) has a hyperbranched structure and demonstrated strong dry and wet adhesion strength on diverse material surfaces. We found that their adhesion strength depended on the concentration of DHHCA. Poly(DHHCA-co-LA) with the lowest concentration of DHHCA showed the highest adhesion strength in water with a value of 2.7 MPa between glasses, while with the highest concentration of DHHCA it exhibited the highest dry adhesion strength with a value of 3.5 MPa, which was comparable to commercial instant super glue. Compared to underwater glues reported previously, our adhesives were able to spread rapidly under water with a low viscosity and worked strongly. Poly(DHHCA-co-LA) also showed long-term stability and kept wet adhesion strength of 2.2 MPa after steeping in water for 1 month at room temperature (initial strength was 2.4 MPa). In this paper, Poly(DHHCA-co-LA) with strong dry and wet adhesion properties and long-term stability was demonstrated for various kinds of applications, especially for wet conditions.
Collapse
Affiliation(s)
| | | | | | | | | | - Mingqing Chen
- Key Laboratory of Synthetic and Biological Colloids, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, China; (X.Y.); (C.D.); (W.Z.); (D.S.); (W.D.)
| | - Daisaku Kaneko
- Key Laboratory of Synthetic and Biological Colloids, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, China; (X.Y.); (C.D.); (W.Z.); (D.S.); (W.D.)
| |
Collapse
|
34
|
Ohzono T, Katoh K, Minamikawa H, Saed MO, Terentjev EM. Internal constraints and arrested relaxation in main-chain nematic elastomers. Nat Commun 2021; 12:787. [PMID: 33542238 PMCID: PMC7862651 DOI: 10.1038/s41467-021-21036-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 01/04/2021] [Indexed: 11/16/2022] Open
Abstract
Nematic liquid crystal elastomers (N-LCE) exhibit intriguing mechanical properties, such as reversible actuation and soft elasticity, which manifests as a wide plateau of low nearly-constant stress upon stretching. N-LCE also have a characteristically slow stress relaxation, which sometimes prevents their shape recovery. To understand how the inherent nematic order retards and arrests the equilibration, here we examine hysteretic stress-strain characteristics in a series of specifically designed main-chain N-LCE, investigating both macroscopic mechanical properties and the microscopic nematic director distribution under applied strains. The hysteretic features are attributed to the dynamics of thermodynamically unfavoured hairpins, the sharp folds on anisotropic polymer strands, the creation and transition of which are restricted by the nematic order. These findings provide a new avenue for tuning the hysteretic nature of N-LCE at both macro- and microscopic levels via different designs of polymer networks, toward materials with highly nonlinear mechanical properties and shape-memory applications.
Collapse
Affiliation(s)
- Takuya Ohzono
- Research Institute for Electronics and Photonics, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan.
| | - Kaoru Katoh
- Biomedical Research Institute, AIST, Tsukuba, Japan
| | | | - Mohand O Saed
- Cavendish Laboratory, University of Cambridge, Cambridge, UK
| | | |
Collapse
|
35
|
Ohzono T, Norikane Y, Saed MO, Terentjev EM. Light-Driven Dynamic Adhesion on Photosensitized Nematic Liquid Crystalline Elastomers. ACS APPLIED MATERIALS & INTERFACES 2020; 12:31992-31997. [PMID: 32609481 DOI: 10.1021/acsami.0c08289] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
In liquid crystal elastomers (LCEs), the internal mechanical loss increases around the nematic-isotropic phase transition and remains high all through the nematic phase, originating from the internal orientational relaxation related to the so-called "soft elasticity". Because the viscoelastic dissipation of the materials affects their adhesion properties, the nematic-isotropic phase transition can cause dramatic changes in the adhesion strength. Although the phase transitions can generally be induced by heat, here, we demonstrate the light-driven transition in dynamic adhesion in dye-doped nematic LCE. The special dye is chosen to efficiently generate local heat on light absorption. The adhesion strength is lowered with fine tunability depending on the light power, which governs the effective local temperature and through that the viscoelastic damping of the system. We demonstrate the light-assisted dynamic control of adhesion in a 90°-peel test and in pick-and-release of objects, which may lead to the development of stimuli-responsive adhesive systems with fine spatio-temporal controls.
Collapse
Affiliation(s)
- Takuya Ohzono
- Research Institute for Electronics and Photonics, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8565, Japan
| | - Yasuo Norikane
- Research Institute for Electronics and Photonics, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8565, Japan
| | - Mohand O Saed
- Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, U.K
| | - Eugene M Terentjev
- Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, U.K
| |
Collapse
|
36
|
Testa P, Chappuis B, Kistler S, Style RW, Heyderman LJ, Dufresne ER. Switchable adhesion of soft composites induced by a magnetic field. SOFT MATTER 2020; 16:5806-5811. [PMID: 32469030 DOI: 10.1039/d0sm00626b] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Switchable adhesives have the potential to improve the manufacturing and recycling of parts, and to enable new modes of motility for soft robots. Here, we demonstrate magnetically-switchable adhesion of a two-phase composite to non-magnetic objects. The composite's continuous phase is a silicone elastomer, and the dispersed phase is a magneto-rheological fluid. The composite is simple to prepare, and to mold into different shapes. When a magnetic field is applied, the magneto-rheological fluid develops a yield stress, which dramatically enhances the composite's adhesive properties. We demonstrate up to a nine-fold increase of the pull-off force of non-magnetic objects in the presence of a 250 mT field.
Collapse
Affiliation(s)
- Paolo Testa
- Laboratory for Mesoscopic Systems, Department of Materials, ETH Zürich, 8093 Zürich, Switzerland.
| | | | | | | | | | | |
Collapse
|
37
|
Traugutt NA, Mistry D, Luo C, Yu K, Ge Q, Yakacki CM. Liquid-Crystal-Elastomer-Based Dissipative Structures by Digital Light Processing 3D Printing. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e2000797. [PMID: 32508011 DOI: 10.1002/adma.202000797] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 04/20/2020] [Indexed: 05/24/2023]
Abstract
Digital Light Processing (DLP) 3D printing enables the creation of hierarchical complex structures with specific micro- and macroscopic architectures that are impossible to achieve through traditional manufacturing methods. Here, this hierarchy is extended to the mesoscopic length scale for optimized devices that dissipate mechanical energy. A photocurable, thus DLP-printable main-chain liquid crystal elastomer (LCE) resin is reported and used to print a variety of complex, high-resolution energy-dissipative devices. Using compressive mechanical testing, the stress-strain responses of 3D-printed LCE lattice structures are shown to have 12 times greater rate-dependence and up to 27 times greater strain-energy dissipation compared to those printed from a commercially available photocurable elastomer resin. The reported behaviors of these structures provide further insight into the much-overlooked energy-dissipation properties of LCEs and can inspire the development of high-energy-absorbing device applications.
Collapse
Affiliation(s)
- Nicholas A Traugutt
- University of Colorado Denver, 1200 Larimer Street, Campus Box 112, Denver, CO, 80217, USA
| | - Devesh Mistry
- University of Colorado Denver, 1200 Larimer Street, Campus Box 112, Denver, CO, 80217, USA
| | - Chaoqian Luo
- University of Colorado Denver, 1200 Larimer Street, Campus Box 112, Denver, CO, 80217, USA
| | - Kai Yu
- University of Colorado Denver, 1200 Larimer Street, Campus Box 112, Denver, CO, 80217, USA
| | - Qi Ge
- Department of Mechanical and Energy Engineering, Southern University of Science and Technology, 1088 Xueyuan Avenue, Shenzhen, 518055, P. R. China
| | - Christopher M Yakacki
- University of Colorado Denver, 1200 Larimer Street, Campus Box 112, Denver, CO, 80217, USA
| |
Collapse
|
38
|
Zhu J, Lu X, Zhang W, Liu X. Substrate-Independent, Reversible, and Easy-Release Ionogel Adhesives with High Bonding Strength. Macromol Rapid Commun 2020; 41:e2000098. [PMID: 32430924 DOI: 10.1002/marc.202000098] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 04/21/2020] [Accepted: 05/03/2020] [Indexed: 11/12/2022]
Abstract
It is highly desirable to develop reversible and easy-release adhesives with high bonding strength for a broad range of substrates, while the adhesion of low-surface-energy materials (e.g., polytetrafluoretyhylene, PTFE) is challenging. Herein, a substrate-independent ionogel adhesive is developed by blending an ionic liquid with the copolymer bearing charged segments. By regulating the viscoelastic properties of the ionogel, the adhesive and cohesive strength of the ionogel can be well balanced to maximize the bonding strength for different substrates. The as-developed ionogel exhibits high bonding strength (>0.3 MPa) for PTFE, plastics, metal, wood, and glass, because the variety of functional groups in the ionogel can form various supramolecular interactions with different substrates. The ionogel also exhibits reversible, easy-release, and reusable properties for multiple times of bonding and on-demand debonding without leaving obvious residues on the substrates. The ionogel has high potential for practical applications as temporal adhesives with high bonding strength.
Collapse
Affiliation(s)
- Jingjing Zhu
- J. Zhu, X. Lu, Dr. W. Zhang, Prof. X. Liu, State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Xiaomeng Lu
- J. Zhu, X. Lu, Dr. W. Zhang, Prof. X. Liu, State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Wei Zhang
- J. Zhu, X. Lu, Dr. W. Zhang, Prof. X. Liu, State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Xiaokong Liu
- J. Zhu, X. Lu, Dr. W. Zhang, Prof. X. Liu, State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| |
Collapse
|
39
|
Saed MO, Terentjev EM. Siloxane crosslinks with dynamic bond exchange enable shape programming in liquid-crystalline elastomers. Sci Rep 2020; 10:6609. [PMID: 32313059 PMCID: PMC7171139 DOI: 10.1038/s41598-020-63508-4] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 03/31/2020] [Indexed: 11/17/2022] Open
Abstract
Liquid crystalline elastomers (LCE) undergo reversible shape changes in response to stimuli, which enables a wide range of smart applications, in soft robotics, adhesive systems or biomedical medical devices. In this study, we introduce a new dynamic covalent chemistry based on siloxane equilibrium exchange into the LCE to enable processing (director alignment, remolding, and welding). Unlike the traditional siloxane based LCE, which were produced by reaction schemes with irreversible bonds (e.g. hydrosilylation), here we use a much more robust reaction (thiol-acrylate/thiol-ene 'double-click' chemistry) to obtain highly uniform dynamically crosslinked networks. Combining the siloxane crosslinker with click chemistry produces exchangeable LCE (xLCE) with tunable properties, low glass transition (-30 °C), controllable nematic to isotropic transition (33 to 70 °C), and a very high vitrification temperature (up to 250 °C). Accordingly, this class of dynamically crosslinked xLCE shows unprecedented thermal stability within the working temperature range (-50 to 140 °C), over many thermal actuation cycles without any creep. Finally, multiple xLCE sharing the same siloxane exchangeable bonds can be welded into single continuous structures to allow for composite materials that sequentially and reversibly undergo multiple phase transformations in different sections of the sample.
Collapse
Affiliation(s)
- Mohand O Saed
- Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge, CB3 0HE, United Kingdom
| | - Eugene M Terentjev
- Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge, CB3 0HE, United Kingdom.
| |
Collapse
|
40
|
Hu J, Kuang ZY, Tao L, Huang YF, Wang Q, Xie HL, Yin JR, Chen EQ. Programmable 3D Shape-Change Liquid Crystalline Elastomer Based on a Vertically Aligned Monodomain with Cross-link Gradient. ACS APPLIED MATERIALS & INTERFACES 2019; 11:48393-48401. [PMID: 31786930 DOI: 10.1021/acsami.9b17393] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A liquid crystalline elastomer (LCE) as a kind of stimuli-responsive materials, which can be fabricated to present the three-dimensional (3D) change in shape, shows a wide range of applications. Herein, we propose a simple and robust way to prepare a 3D shape-change actuator based on gradient cross-linking of the vertically aligned monodomain of liquid crystals (LCs). First, gold nanoparticles grafted by liquid crystalline polymers (LCPs) are used to induce the homeotropic orientation of the LC monomer and cross-linkers. Then, photopolymerization under UV irradiation is carried out, which can result in the LCE film with a cross-link gradient. Different from the typical LCEs with homogenous alignment that usually show the shape change of extension/contraction, the obtained vertically aligned LCE film exhibits excellent bendability under a thermal stimulus. The nanoindentation experiment demonstrates that the deformation of LCE films comes from the difference in Young's modulus on two sides of the thin film. Simply scissoring the thin film can prepare the samples with different bending angles under the fixed length. Moreover, using a photomask to pattern the film during photopolymerization can realize the complex 3D deformation, such as bend, fold, and buckling. Further, the patterned LCE film doped with multiwalled carbon nanotubes modified by LCPs (CNT-PDB) can act as a light-fueled microwalker with fast crawl behavior.
Collapse
Affiliation(s)
- Jun Hu
- Key Lab of Environment-friendly Chemistry and Application in Ministry of Education, and Key Laboratory of Advanced Functional Polymer Materials of Colleges, Universities of Hunan Province and College of Chemistry , Xiangtan University , Xiangtan , Hunan 411105 , China
| | - Ze-Yang Kuang
- Key Lab of Environment-friendly Chemistry and Application in Ministry of Education, and Key Laboratory of Advanced Functional Polymer Materials of Colleges, Universities of Hunan Province and College of Chemistry , Xiangtan University , Xiangtan , Hunan 411105 , China
| | - Lei Tao
- Key Lab of Environment-friendly Chemistry and Application in Ministry of Education, and Key Laboratory of Advanced Functional Polymer Materials of Colleges, Universities of Hunan Province and College of Chemistry , Xiangtan University , Xiangtan , Hunan 411105 , China
| | - Yi-Fei Huang
- College of Civil Engineering & Mechanics , Xiangtan University , Xiangtan 411105 , Hunan Province, China
| | - Qing Wang
- Key Lab of Environment-friendly Chemistry and Application in Ministry of Education, and Key Laboratory of Advanced Functional Polymer Materials of Colleges, Universities of Hunan Province and College of Chemistry , Xiangtan University , Xiangtan , Hunan 411105 , China
| | - He-Lou Xie
- Key Lab of Environment-friendly Chemistry and Application in Ministry of Education, and Key Laboratory of Advanced Functional Polymer Materials of Colleges, Universities of Hunan Province and College of Chemistry , Xiangtan University , Xiangtan , Hunan 411105 , China
| | - Jiu-Ren Yin
- College of Civil Engineering & Mechanics , Xiangtan University , Xiangtan 411105 , Hunan Province, China
| | - Er-Qiang Chen
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, College of Chemistry and Molecular Engineering , Peking University , Beijing 100871 , China
| |
Collapse
|