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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: 0] [Impact Index Per Article: 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.
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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
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Abdelrahman MK, Wagner RJ, Kalairaj MS, Zadan M, Kim MH, Jang LK, Wang S, Javed M, Dana A, Singh KA, Hargett SE, Gaharwar AK, Majidi C, Vernerey FJ, Ware TH. Material assembly from collective action of shape-changing polymers. NATURE MATERIALS 2024; 23:281-289. [PMID: 38177377 DOI: 10.1038/s41563-023-01761-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 11/14/2023] [Indexed: 01/06/2024]
Abstract
Some animals form transient, responsive and solid-like ensembles through dynamic structural interactions. These ensembles demonstrate emergent responses such as spontaneous self-assembly, which are difficult to achieve in synthetic soft matter. Here we use shape-morphing units comprising responsive polymers to create solids that self-assemble, modulate their volume and disassemble on demand. The ensemble is composed of a responsive hydrogel, liquid crystal elastomer or semicrystalline polymer ribbons that reversibly bend or twist. The dispersions of these ribbons mechanically interlock, inducing reversible aggregation. The aggregated liquid crystal elastomer ribbons have a 12-fold increase in the yield stress compared with cooled dispersion and contract by 34% on heating. Ribbon type, concentration and shape dictate the aggregation and govern the global mechanical properties of the solid that forms. Coating liquid crystal elastomer ribbons with a liquid metal begets photoresponsive and electrically conductive aggregates, whereas seeding cells on hydrogel ribbons enables self-assembling three-dimensional scaffolds, providing a versatile platform for the design of dynamic materials.
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Affiliation(s)
- Mustafa K Abdelrahman
- Department of Materials Science and Engineering, Texas A&M University, College Station, TX, USA
| | - Robert J Wagner
- Mechanical Engineering Department, Materials Science and Engineering Program, University of Colorado, Boulder, CO, USA
- Department of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, USA
| | | | - Mason Zadan
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Min Hee Kim
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
| | - Lindy K Jang
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
- Materials Engineering Division, Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - Suitu Wang
- Department of Materials Science and Engineering, Texas A&M University, College Station, TX, USA
| | - Mahjabeen Javed
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
| | - Asaf Dana
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
| | - Kanwar Abhay Singh
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
| | - Sarah E Hargett
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
| | - Akhilesh K Gaharwar
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
| | - Carmel Majidi
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Franck J Vernerey
- Mechanical Engineering Department, Materials Science and Engineering Program, University of Colorado, Boulder, CO, USA
| | - Taylor H Ware
- Department of Materials Science and Engineering, Texas A&M University, College Station, TX, USA.
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA.
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Saeed MH, Choi MY, Kim K, Lee JH, Kim K, Kim D, Kim SU, Kim H, Ahn SK, Lan R, Na JH. Electrostatically Powered Multimode Liquid Crystalline Elastomer Actuators. ACS APPLIED MATERIALS & INTERFACES 2023; 15:56285-56292. [PMID: 37991738 DOI: 10.1021/acsami.3c13140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2023]
Abstract
Soft actuators based on liquid crystalline elastomers (LCEs) are captivating significant interest because of their unique properties combining the programmable liquid crystalline molecular order and elasticity of polymeric materials. For practical applications, the ability to perform multimodal shape changes in a single LCE actuator at a subsecond level is a bottleneck. Here, we fabricate a monodomain LCE powered by electrostatic force, which enables fast multidirectional bending, oscillation, rotation, and complex actuation with a high degree of freedom. By tuning the dielectric constant and resistivity in LCE gels, a complete cycle of oscillation and rotation only takes 0.1 s. In addition, monodomain actuators exhibit anisotropic actuation behaviors that promise a more complex deployment in a potential electromechanical system. The presented study will pave the way for electrostatically controllable isothermal manipulation for a fast and multimode soft actuator.
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Affiliation(s)
- Mohsin Hassan Saeed
- Department of Electrical, Electronics and Communication Engineering Education, Chungnam National University, Daejeon 34134, Republic of Korea
| | - Moon-Young Choi
- Department of Convergence System Engineering, Chungnam National University, Daejeon 34134, Republic of Korea
| | - Kitae Kim
- Department of Convergence System Engineering, Chungnam National University, Daejeon 34134, Republic of Korea
| | - Jin-Hyeong Lee
- School of Chemical Engineering, Pusan National University, Busan 46241, Republic of Korea
| | - Keumbee Kim
- School of Chemical Engineering, Pusan National University, Busan 46241, Republic of Korea
| | - Dowon Kim
- Department of Electrical, Electronics and Communication Engineering Education, Chungnam National University, Daejeon 34134, Republic of Korea
| | - Se-Um Kim
- Department of Electrical and Information Engineering, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea
| | - Hyun Kim
- Advanced Materials Division, Korea Research Institute of Chemical Technology, Daejeon 34114, Republic of Korea
| | - Suk-Kyun Ahn
- School of Chemical Engineering, Pusan National University, Busan 46241, Republic of Korea
- Department of Polymer Science and Engineering, Pusan National University, Busan 46241, Republic of Korea
| | - Ruochen Lan
- Institute of Advanced Materials, Jiangxi Normal University, Nanchang 330022, China
| | - Jun-Hee Na
- Department of Electrical, Electronics and Communication Engineering Education, Chungnam National University, Daejeon 34134, Republic of Korea
- Department of Convergence System Engineering, Chungnam National University, Daejeon 34134, Republic of Korea
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LoGrande K, Shankar MR, Dayal K. A dimensionally-reduced nonlinear elasticity model for liquid crystal elastomer strips with transverse curvature. SOFT MATTER 2023; 19:8764-8778. [PMID: 37938345 DOI: 10.1039/d3sm00664f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2023]
Abstract
Liquid crystalline elastomers (LCEs) are active materials that are of interest due to their programmable response to various external stimuli such as light and heat. When exposed to these stimuli, the anisotropy in the response of the material is governed by the nematic director, which is a continuum parameter that is defined as the average local orientation of the mesogens in the liquid crystal phase. This nematic director can be programmed to be heterogeneous in space, creating a vast design space that is useful for applications ranging from artificial ligaments to deployable structures to self-assembling mechanisms. Even when specialized to long and thin strips of LCEs - the focus of this work - the vast design space has required the use of numerical simulations to aid in experimental discovery. To mitigate the computational expense of full 3-d numerical simulations, several dimensionally-reduced rod and ribbon models have been developed for LCE strips, but these have not accounted for the possibility of initial transverse curvature, like carpenter's tape spring. Motivated by recent experiments showing that transversely-curved LCE strips display a rich variety of configurations, this work derives a dimensionally-reduced 1-d model for pre-curved LCE strips. The 1-d model is validated against full 3-d finite element calculations, and it is also shown to capture experimental observations, including tape-spring-like localizations, in activated LCE strips.
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Affiliation(s)
- Kevin LoGrande
- Department of Civil and Environmental Engineering, Carnegie Mellon University, USA.
- Computation and Information Sciences Directorate, CCDC Army Research Lab, USA
| | - M Ravi Shankar
- Department of Industrial Engineering, University of Pittsburgh, USA
| | - Kaushik Dayal
- Department of Civil and Environmental Engineering, Carnegie Mellon University, USA.
- Center for Nonlinear Analysis, Department of Mathematical Sciences, Carnegie Mellon University, USA
- Department of Mechanical Engineering, Carnegie Mellon University, USA
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Ohzono T, Koyama E. Enhanced photocontrollable dynamic adhesion of nematic elastomers on rough surfaces. POLYMER 2022. [DOI: 10.1016/j.polymer.2022.125377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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