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Leanza S, Wu S, Sun X, Qi HJ, Zhao RR. Active Materials for Functional Origami. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2302066. [PMID: 37120795 DOI: 10.1002/adma.202302066] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2023] [Revised: 04/13/2023] [Indexed: 06/19/2023]
Abstract
In recent decades, origami has been explored to aid in the design of engineering structures. These structures span multiple scales and have been demonstrated to be used toward various areas such as aerospace, metamaterial, biomedical, robotics, and architectural applications. Conventionally, origami or deployable structures have been actuated by hands, motors, or pneumatic actuators, which can result in heavy or bulky structures. On the other hand, active materials, which reconfigure in response to external stimulus, eliminate the need for external mechanical loads and bulky actuation systems. Thus, in recent years, active materials incorporated with deployable structures have shown promise for remote actuation of light weight, programmable origami. In this review, active materials such as shape memory polymers (SMPs) and alloys (SMAs), hydrogels, liquid crystal elastomers (LCEs), magnetic soft materials (MSMs), and covalent adaptable network (CAN) polymers, their actuation mechanisms, as well as how they have been utilized for active origami and where these structures are applicable is discussed. Additionally, the state-of-the-art fabrication methods to construct active origami are highlighted. The existing structural modeling strategies for origami, the constitutive models used to describe active materials, and the largest challenges and future directions for active origami research are summarized.
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Affiliation(s)
- Sophie Leanza
- Department of Mechanical Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Shuai Wu
- Department of Mechanical Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Xiaohao Sun
- The George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - H Jerry Qi
- The George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Ruike Renee Zhao
- Department of Mechanical Engineering, Stanford University, Stanford, CA, 94305, USA
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2
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Qiu W, He X, Fang Z, Wang Y, Dong K, Zhang G, Xu X, Ge Q, Xiong Y. Shape-Tunable 4D Printing of LCEs via Cooling Rate Modulation: Stimulus-Free Locking of Actuated State at Room Temperature. ACS APPLIED MATERIALS & INTERFACES 2023; 15:47509-47519. [PMID: 37769329 DOI: 10.1021/acsami.3c10210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/30/2023]
Abstract
Liquid crystal elastomers (LCEs) have garnered considerable attention in the field of four-dimensional (4D) printing due to their large, reversible, and anisotropic shape-morphing capabilities. By utilizing direct ink writing, intricate LCE structures with programmable shape morphing can be achieved. However, the maintenance of the actuated state for LCEs requires continuous and substantial external stimuli, presenting challenges for practical applications, particularly under ambient conditions. This study reports a straightforward and effective physical approach to lock the actuated state of LCEs through rapid cooling while preserving their reversible performance. Rapid cooling significantly reduces the mobility of the lightly cross-linked network in LCEs, resulting in a notably slow recovery of mesogen alignment. As a result, the locked LCE structures retain their actuated state even at room temperature. Moreover, we demonstrate the ability to achieve tunable shapes between the original and actuated states by modulating the cooling rate, i.e., varying the temperature and type of cooling medium. The proposed method opens up new possibilities to achieve stable and tunable shape locking of soft devices for engineering applications.
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Affiliation(s)
- Wanglin Qiu
- School of System Design and Intelligent Manufacturing, Southern University of Science and Technology, Shenzhen 518055, P. R. China
| | - Xiangnan He
- Department of Mechanical and Energy Engineering, Southern University of Science and Technology, Shenzhen 518055, P. R. China
| | - Zeming Fang
- School of System Design and Intelligent Manufacturing, Southern University of Science and Technology, Shenzhen 518055, P. R. China
| | - Yaohui Wang
- School of System Design and Intelligent Manufacturing, Southern University of Science and Technology, Shenzhen 518055, P. R. China
| | - Ke Dong
- School of System Design and Intelligent Manufacturing, Southern University of Science and Technology, Shenzhen 518055, P. R. China
| | - Guoquan Zhang
- School of System Design and Intelligent Manufacturing, Southern University of Science and Technology, Shenzhen 518055, P. R. China
| | - Xuguang Xu
- School of System Design and Intelligent Manufacturing, Southern University of Science and Technology, Shenzhen 518055, P. R. China
| | - Qi Ge
- Department of Mechanical and Energy Engineering, Southern University of Science and Technology, Shenzhen 518055, P. R. China
| | - Yi Xiong
- School of System Design and Intelligent Manufacturing, Southern University of Science and Technology, Shenzhen 518055, P. R. China
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3
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Chen M, Gao M, Bai L, Zheng H, Qi HJ, Zhou K. Recent Advances in 4D Printing of Liquid Crystal Elastomers. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2209566. [PMID: 36461147 DOI: 10.1002/adma.202209566] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 11/22/2022] [Indexed: 06/09/2023]
Abstract
Liquid crystal elastomers (LCEs) are renowned for their large, reversible, and anisotropic shape change in response to various external stimuli due to their lightly cross-linked polymer networks with an oriented mesogen direction, thus showing great potential for applications in robotics, bio-medics, electronics, optics, and energy. To fully take advantage of the anisotropic stimuli-responsive behaviors of LCEs, it is preferable to achieve a locally controlled mesogen alignment into monodomain orientations. In recent years, the application of 4D printing to LCEs opens new doors for simultaneously programming the mesogen alignment and the 3D geometry, offering more opportunities and higher feasibility for the fabrication of 4D-printed LCE objects with desirable stimuli-responsive properties. Here, the state-of-the-art advances in 4D printing of LCEs are reviewed, with emphasis on both the mechanisms and potential applications. First, the fundamental properties of LCEs and the working principles of the representative 4D printing techniques are briefly introduced. Then, the fabrication of LCEs by 4D printing techniques and the advantages over conventional manufacturing methods are demonstrated. Finally, perspectives on the current challenges and potential development trends toward the 4D printing of LCEs are discussed, which may shed light on future research directions in this new field.
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Affiliation(s)
- Mei Chen
- Singapore Centre for 3D Printing, School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore, 639798, Singapore
- HP-NTU Digital Manufacturing Corporate Lab, School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Ming Gao
- Singapore Centre for 3D Printing, School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore, 639798, Singapore
- HP-NTU Digital Manufacturing Corporate Lab, School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Lichun Bai
- School of Traffic and Transportation Engineering, Central South University, Changsha, 410075, China
| | - Han Zheng
- Singapore Centre for 3D Printing, School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - H Jerry Qi
- School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Kun Zhou
- Singapore Centre for 3D Printing, School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore, 639798, Singapore
- HP-NTU Digital Manufacturing Corporate Lab, School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore, 639798, Singapore
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Luo Y, Ho CL, Helliker BR, Katifori E. Flow-network-controlled shape transformation of a thin membrane through differential fluid storage and surface expansion. Phys Rev E 2023; 107:024419. [PMID: 36932519 DOI: 10.1103/physreve.107.024419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 01/03/2023] [Indexed: 06/18/2023]
Abstract
The mechanical properties of a thin, planar material, perfused by an embedded flow network, have been suggested to be potentially changeable locally and globally by fluid transport and storage, which can result in both small- and large-scale deformations such as out-of-plane buckling. In these processes, fluid absorption and storage eventually cause the material to locally swell. Different parts can hydrate and swell unevenly, prompting a differential expansion of the surface. In order to computationally study the hydraulically induced differential swelling and buckling of such a membrane, we develop a network model that describes both the membrane shape and fluid movement, coupling mechanics with hydrodynamics. We simulate the time-dependent fluid distribution in the flow network based on a spatially explicit resistor network model with local fluid-storage capacitance. The shape of the surface is modeled by a spring network produced by a tethered mesh discretization, in which local bond rest lengths are adjusted instantaneously according to associated local fluid content in the capacitors in a quasistatic way. We investigate the effects of various designs of the flow network, including overall hydraulic traits (resistance and capacitance) and hierarchical architecture (arrangement of major and minor veins), on the specific dynamics of membrane shape transformation. To quantify these effects, we explore the correlation between local Gaussian curvature and relative stored fluid content in each hierarchy by using linear regression, which reveals that stronger correlations could be induced by less densely connected major veins. This flow-controlled mechanism of shape transformation was inspired by the blooming of flowers through the unfolding of petals. It can potentially offer insights for other reversible motions observed in plants induced by differential turgor and water transport through the xylem vessels, as well as engineering applications.
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Affiliation(s)
- Yongtian Luo
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Che-Ling Ho
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Brent R Helliker
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Eleni Katifori
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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Abstract
Photomechanical materials perform mechanical work in response to illumination. Photoisomerization-based photomechanical materials may operate in different regimes depending on the intensity of the illuminating light. We examine the photoresponse of liquid crystalline azo-acrylate networks and show that a material property, the characteristic intensity of the material, defines the boundaries between different regimes. Asymptotic analysis indicates that whereas at low relative light levels, photostress is proportional to intensity, at high levels, it is proportional to fluence. Model predictions are in good agreement with the experimental results.
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6
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Wang KF, Wang BL. Is there only one equilibrium configuration for spontaneous bending of liquid crystal elastomer circular plates with free edges? THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2021; 44:124. [PMID: 34617149 DOI: 10.1140/epje/s10189-021-00126-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 09/15/2021] [Indexed: 06/13/2023]
Abstract
In this paper, the spontaneous bending of a liquid crystal elastomer (LCE) circular plate under light illumination is investigated. The large bending deformation configurations for the LCE circular plate with free edges are obtained by minimizing the potential energy. It is found that for an LCE circular plate with random distribution of liquid crystal molecules, if the light intensity is small, there is only one equilibrium configuration for bending of the LCE circular plate. However, when the light intensity reaches a critical value, the circular plate will buckle and there will be three possible equilibrium configurations. On the other hand, for an LCE circular plate with uniform orientation of liquid crystal molecules, the strain induced by light is anisotropic, and there is only one equilibrium configuration. In addition, bending shapes of the LCE circular plate depend on its thickness. These results may be useful for designing light-driven LCE devices.
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Affiliation(s)
- K F Wang
- School of Science, Harbin Institute of Technology, Shenzhen, 518055, China.
| | - B L Wang
- School of Science, Harbin Institute of Technology, Shenzhen, 518055, China
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7
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Mihai LA, Wang H, Guilleminot J, Goriely A. Nematic liquid crystalline elastomers are aeolotropic materials. Proc Math Phys Eng Sci 2021; 477:20210259. [PMID: 35153581 PMCID: PMC8424302 DOI: 10.1098/rspa.2021.0259] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 08/04/2021] [Indexed: 11/12/2022] Open
Abstract
Continuum models describing ideal nematic solids are widely used in theoretical studies of liquid crystal elastomers. However, experiments on nematic elastomers show a type of anisotropic response that is not predicted by the ideal models. Therefore, their description requires an additional term coupling elastic and nematic responses, to account for aeolotropic effects. In order to better understand the observed elastic response of liquid crystal elastomers, we analyse theoretically and computationally different stretch and shear deformations. We then compare the elastic moduli in the infinitesimal elastic strain limit obtained from the molecular dynamics simulations with the ones derived theoretically, and show that they are better explained by including nematic order effects within the continuum framework.
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Affiliation(s)
- L Angela Mihai
- School of Mathematics, Cardiff University, Senghennydd Road, Cardiff CF24 4AG, UK
| | - Haoran Wang
- Department of Mechanical and Aerospace Engineering,Utah State University, Logan, UT 84322-4130, USA
| | - Johann Guilleminot
- Department of Civil and Environmental Engineering, Duke University, Durham, NC 27708-0287, USA
| | - Alain Goriely
- Mathematical Institute, University of Oxford, Woodstock Road, Oxford OX2 6GG, UK
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8
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Lavrentovich OD. Design of nematic liquid crystals to control microscale dynamics. LIQUID CRYSTALS REVIEWS 2021; 8:59-129. [PMID: 34956738 PMCID: PMC8698256 DOI: 10.1080/21680396.2021.1919576] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 04/11/2021] [Indexed: 05/25/2023]
Abstract
The dynamics of small particles, both living such as swimming bacteria and inanimate, such as colloidal spheres, has fascinated scientists for centuries. If one could learn how to control and streamline their chaotic motion, that would open technological opportunities in the transformation of stored or environmental energy into systematic motion, with applications in micro-robotics, transport of matter, guided morphogenesis. This review presents an approach to command microscale dynamics by replacing an isotropic medium with a liquid crystal. Orientational order and associated properties, such as elasticity, surface anchoring, and bulk anisotropy, enable new dynamic effects, ranging from the appearance and propagation of particle-like solitary waves to self-locomotion of an active droplet. By using photoalignment, the liquid crystal can be patterned into predesigned structures. In the presence of the electric field, these patterns enable the transport of solid and fluid particles through nonlinear electrokinetics rooted in anisotropy of conductivity and permittivity. Director patterns command the dynamics of swimming bacteria, guiding their trajectories, polarity of swimming, and distribution in space. This guidance is of a higher level of complexity than a simple following of the director by rod-like microorganisms. Namely, the director gradients mediate hydrodynamic interactions of bacteria to produce an active force and collective polar modes of swimming. The patterned director could also be engraved in a liquid crystal elastomer. When an elastomer coating is activated by heat or light, these patterns produce a deterministic surface topography. The director gradients define an activation force that shapes the elastomer in a manner similar to the active stresses triggering flows in active nematics. The patterned elastomer substrates could be used to define the orientation of cells in living tissues. The liquid-crystal guidance holds a major promise in achieving the goal of commanding microscale active flows.
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Affiliation(s)
- Oleg D Lavrentovich
- Advanced Materials and Liquid Crystal Institute, Department of Physics, Materials Science Graduate Program, Kent State University, Kent, OH 44242, USA
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9
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Liu Y, Zhao D. Boundary effect on the spontaneous deformation of a liquid crystal elastomer plate with arbitrary director orientation. Phys Rev E 2021; 103:012701. [PMID: 33601504 DOI: 10.1103/physreve.103.012701] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 12/21/2020] [Indexed: 11/07/2022]
Abstract
Except for director orientation, the deformation modes of constrained liquid crystal elastomer thin plate display specimen geometry size dependence due to the boundary effect. In this paper, the effect of plate geometry size on the spontaneous deformation of a simply supported liquid crystal elastomer plate is studied. The relation between the deformation modes with director orientation and plate geometry size are investigated. Results show that the deformation modes are decided by the director orientation for a certain liquid crystal elastomer, but the geometry size affects the mode transformation with respect to the director. These results are supposed to be used in the design and application of liquid crystal elastomer-based smart actuators or sensors.
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Affiliation(s)
- Ying Liu
- School of Civil Engineering, Beijing Jiaotong University, Beijing 100044 China
| | - Dong Zhao
- School of Civil Engineering, Beijing Jiaotong University, Beijing 100044 China
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10
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Wan X, Luo L, Liu Y, Leng J. Direct Ink Writing Based 4D Printing of Materials and Their Applications. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2020; 7:2001000. [PMID: 32832355 PMCID: PMC7435246 DOI: 10.1002/advs.202001000] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 05/30/2020] [Indexed: 05/19/2023]
Abstract
4D printing has attracted academic interest in the recent years because it endows static printed structures with dynamic properties with the change of time. The shapes, functionalities, or properties of the 4D printed objects could alter under various stimuli such as heat, light, electric, and magnetic field. Briefly, 4D printing is the development of 3D printing with the fourth dimension of time. Among the fabrication techniques that have been employed for 4D printing, the direct ink writing technique shows superiority due to its open source for various types of materials. Herein, the state-of-the-art achievements about the topic of 4D printing through direct ink writing are summarized. The types of materials, printing strategies, actuated methods, and their potential applications are discussed in detail. To date, most efforts have been devoted to shape-shifting materials, including shape memory polymers, hydrogels, and liquid crystal elastomers, showing great prospects in areas ranging from the biomedical field to robotics. Finally, the current challenges and outlook toward 4D printing based on direct ink writing are also pointed out to leave open a significant space for future innovation.
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Affiliation(s)
- Xue Wan
- Center for Composite Materials and StructuresHarbin Institute of TechnologyHarbin150080P. R. China
| | - Lan Luo
- Center for Composite Materials and StructuresHarbin Institute of TechnologyHarbin150080P. R. China
| | - Yanju Liu
- Department of Astronautical Science and MechanicsHarbin Institute of TechnologyHarbin150001P. R. China
| | - Jinsong Leng
- Center for Composite Materials and StructuresHarbin Institute of TechnologyHarbin150080P. R. China
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11
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Zhao D, Liu Y. Light-induced spontaneous bending of a simply supported liquid crystal elastomer rectangular plate. Phys Rev E 2020; 101:042701. [PMID: 32422828 DOI: 10.1103/physreve.101.042701] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2019] [Accepted: 04/07/2020] [Indexed: 11/07/2022]
Abstract
Designing the director alignment of a liquid crystal elastomer (LCE) is a key tuning approach for LCE based smart devices. In this paper, the spontaneous strain of the LCE with arbitrary three-dimensional director orientation is derived, and the governing equation for a simply supported LCE rectangular plate is established. By using the finite difference method, the bending configurations are obtained. Different from the freestanding case, three bending modes, that is, unimodal, bimodal, and trimodal modes, are observed for the simply supported rectangular LCE plate. The relation between the bending modes and the director orientation is established. This paper enhances the understanding and facilitates the design of LCE based intelligent light driven devices.
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Affiliation(s)
- Dong Zhao
- School of Civil Engineering, Beijing Jiaotong University, Beijing 100044, China
| | - Ying Liu
- School of Civil Engineering, Beijing Jiaotong University, Beijing 100044, China
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12
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Liu L, Broer DJ, Onck PR. Travelling waves on photo-switchable patterned liquid crystal polymer films directed by rotating polarized light. SOFT MATTER 2019; 15:8040-8050. [PMID: 31595940 DOI: 10.1039/c9sm01594a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Nature employs travelling waves to generate propulsion of fluids, cells and organisms. This has inspired the development of responsive material systems based on different external triggers. Especially light-actuation is suitable because of its remote control and scalability, but often complex, moving light sources are required. Here, we developed a method that only requires flood exposure by rotating the linear polarization of light to generate propagating surface waves on azobenzene-modified liquid crystalline polymer films. We built a photomechanical computational model that accounts for the attenuation of polarized light and trans-to-cis isomerization of azobenzene. A non-uniform in-plane distribution of the liquid crystal molecules allows for the generation of travelling surface waves whose amplitude, speed and direction can be controlled through the intensity, rotation direction and rotation speed of the linear polarization of a light source. Our method opens new avenues for motion control based on light-responsive topographical transformations for application in microfluidic lab-on-chip systems and soft robotics.
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Affiliation(s)
- Ling Liu
- Micromechanics of Materials, Zernike Institute for Advanced Materials, University of Groningen, 9747 AG Groningen, The Netherlands.
| | - Dirk J Broer
- Department of Chemical Engineering and Chemistry & Institute for Complex Molecular Systems (ICMS), Technology University of Eindhoven, 5600 MB Eindhoven, The Netherlands
| | - Patrick R Onck
- Micromechanics of Materials, Zernike Institute for Advanced Materials, University of Groningen, 9747 AG Groningen, The Netherlands.
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13
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Brannum MT, Auguste AD, Donovan BR, Godman NP, Matavulj VM, Steele AM, Korley LTJ, Wnek GE, White TJ. Deformation and Elastic Recovery of Acrylate-Based Liquid Crystalline Elastomers. Macromolecules 2019. [DOI: 10.1021/acs.macromol.9b01092] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Michelle T. Brannum
- Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, Ohio 45433, United States
- Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Anesia D. Auguste
- Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, Ohio 45433, United States
| | - Brian R. Donovan
- Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, Ohio 45433, United States
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309, United States
| | - Nicholas P. Godman
- Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, Ohio 45433, United States
| | - Valentina M. Matavulj
- Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, Ohio 45433, United States
- Azimuth Corporation, Beavercreek, Ohio 45431, United States
| | - Aubrey M. Steele
- Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, Ohio 45433, United States
- Azimuth Corporation, Beavercreek, Ohio 45431, United States
| | - LaShanda T. J. Korley
- Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, Ohio 44106, United States
- Department of Materials Science and Engineering and Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19716, United States
| | - Gary E. Wnek
- Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Timothy J. White
- Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, Ohio 45433, United States
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309, United States
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14
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Krieger MS, Dias MA. Tunable wrinkling of thin nematic liquid crystal elastomer sheets. Phys Rev E 2019; 100:022701. [PMID: 31574719 DOI: 10.1103/physreve.100.022701] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Indexed: 11/07/2022]
Abstract
Instabilities in thin elastic sheets, such as wrinkles, are of broad interest both from a fundamental viewpoint and also because of their potential for engineering applications. Nematic liquid crystal elastomers offer a new form of control of these instabilities through direct coupling between microscopic degrees of freedom, resulting from orientational ordering of rodlike molecules, and macroscopic strain. By a standard method of dimensional reduction, we construct a plate theory for thin sheets of nematic elastomer. We then apply this theory to the study of the formation of wrinkles due to compression of a thin sheet of nematic liquid crystal elastomer atop an elastic or fluid substrate. We find the scaling of the wrinkle wavelength in terms of material parameters and the applied compression. The wavelength of the wrinkles is found to be nonmonotonic in the compressive strain due to the presence of the nematic. Finally, due to soft modes, the critical stress for the appearance of wrinkles can be much higher than in an isotropic elastomer and depends nontrivially on the manner in which the elastomer was prepared.
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Affiliation(s)
- Madison S Krieger
- Program for Evolutionary Dynamics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Marcelo A Dias
- Department of Engineering, Aarhus University, Inge Lehmanns Gade 10, 8000 Aarhus C, Denmark.,Aarhus University Centre for Integrated Materials Research-iMAT, Ny Munkegade 120, 8000 Aarhus C, Denmark
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15
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Plucinsky P, Kowalski BA, White TJ, Bhattacharya K. Patterning nonisometric origami in nematic elastomer sheets. SOFT MATTER 2018; 14:3127-3134. [PMID: 29624199 DOI: 10.1039/c8sm00103k] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Nematic elastomers dramatically change their shape in response to diverse stimuli including light and heat. In this paper, we provide a systematic framework for the design of complex three dimensional shapes through the actuation of heterogeneously patterned nematic elastomer sheets. These sheets are composed of nonisometric origami building blocks which, when appropriately linked together, can actuate into a diverse array of three dimensional faceted shapes. We demonstrate both theoretically and experimentally that the nonisometric origami building blocks actuate in the predicted manner, and that the integration of multiple building blocks leads to complex, yet predictable and robust, shapes. We then show that this experimentally realized functionality enables a rich design landscape for actuation using nematic elastomers. We highlight this landscape through examples, which utilize large arrays of these building blocks to realize a desired three dimensional origami shape. In combination, these results amount to an engineering design principle, which provides a template for the programming of arbitrarily complex three dimensional shapes on demand.
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Affiliation(s)
- Paul Plucinsky
- Aerospace and Engineering Mechanics, University of Minnesota, Minneapolis, MN 55455, USA
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16
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Liu L, Onck PR. Topographical changes in photo-responsive liquid crystal films: a computational analysis. SOFT MATTER 2018; 14:2411-2428. [PMID: 29512661 DOI: 10.1039/c7sm02474f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Switchable materials in response to external stimuli serve as building blocks to construct microscale functionalized actuators and sensors. Azobenzene-modified liquid crystal (LC) polymeric networks, that combine liquid crystalline orientational order and elasticity, reversibly undergo conformational changes powered by light. We present a computational framework to describe photo-induced topographical transformations of azobenzene-modified LC glassy polymer coatings. A nonlinear light penetration model is combined with an opto-mechanical constitutive relation to simulate various ordered and corrugated topographical textures resulting from aligned or randomly distributed LC molecule orientations. Our results shed light on the fundamental physical mechanisms of light-triggered surface undulations and can be used as guidelines to optimize surface modulation and roughness in emerging fields that involve haptics interfacing, friction control and wetting manipulation.
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Affiliation(s)
- Ling Liu
- Micromechanics of Materials, Zernike Institute for Advanced Materials, 9747 AG, Groningen, The Netherlands.
| | - Patrick R Onck
- Micromechanics of Materials, Zernike Institute for Advanced Materials, 9747 AG, Groningen, The Netherlands.
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17
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Babakhanova G, Turiv T, Guo Y, Hendrikx M, Wei QH, Schenning APHJ, Broer DJ, Lavrentovich OD. Liquid crystal elastomer coatings with programmed response of surface profile. Nat Commun 2018; 9:456. [PMID: 29386512 PMCID: PMC5792610 DOI: 10.1038/s41467-018-02895-9] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Accepted: 01/05/2018] [Indexed: 11/13/2022] Open
Abstract
Stimuli-responsive liquid crystal elastomers with molecular orientation coupled to rubber-like elasticity show a great potential as elements in soft robotics, sensing, and transport systems. The orientational order defines their mechanical response to external stimuli, such as thermally activated muscle-like contraction. Here we demonstrate a dynamic thermal control of the surface topography of an elastomer prepared as a coating with a pattern of in-plane molecular orientation. The inscribed pattern determines whether the coating develops elevations, depressions, or in-plane deformations when the temperature changes. The deterministic dependence of the out-of-plane dynamic profile on the in-plane orientation is explained by activation forces. These forces are caused by stretching-contraction of the polymer networks and by spatially varying molecular orientation. The activation force concept brings the responsive liquid crystal elastomers into the domain of active matter. The demonstrated relationship can be used to design coatings with functionalities that mimic biological tissues such as skin.
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Affiliation(s)
- Greta Babakhanova
- Liquid Crystal Institute, Kent State University, Kent, OH, 44242, USA
- Chemical Physics Interdisciplinary Program, Kent State University, Kent, OH, 44242, USA
| | - Taras Turiv
- Liquid Crystal Institute, Kent State University, Kent, OH, 44242, USA
- Chemical Physics Interdisciplinary Program, Kent State University, Kent, OH, 44242, USA
| | - Yubing Guo
- Liquid Crystal Institute, Kent State University, Kent, OH, 44242, USA
- Chemical Physics Interdisciplinary Program, Kent State University, Kent, OH, 44242, USA
| | - Matthew Hendrikx
- Functional Organic Materials and Devices, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, 5612 AZAE, Eindhoven, The Netherlands
- Institute for Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands
| | - Qi-Huo Wei
- Liquid Crystal Institute, Kent State University, Kent, OH, 44242, USA
- Chemical Physics Interdisciplinary Program, Kent State University, Kent, OH, 44242, USA
| | - Albert P H J Schenning
- Functional Organic Materials and Devices, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, 5612 AZAE, Eindhoven, The Netherlands
- Institute for Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands
| | - Dirk J Broer
- Functional Organic Materials and Devices, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, 5612 AZAE, Eindhoven, The Netherlands
- Institute for Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands
| | - Oleg D Lavrentovich
- Liquid Crystal Institute, Kent State University, Kent, OH, 44242, USA.
- Chemical Physics Interdisciplinary Program, Kent State University, Kent, OH, 44242, USA.
- Department of Physics, Kent State University, Kent, OH, 44242, USA.
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18
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White TJ. Photomechanical effects in liquid crystalline polymer networks and elastomers. ACTA ACUST UNITED AC 2018. [DOI: 10.1002/polb.24576] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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19
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Ambulo CP, Burroughs JJ, Boothby JM, Kim H, Shankar MR, Ware TH. Four-dimensional Printing of Liquid Crystal Elastomers. ACS APPLIED MATERIALS & INTERFACES 2017; 9:37332-37339. [PMID: 28967260 DOI: 10.1021/acsami.7b11851] [Citation(s) in RCA: 190] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Three-dimensional structures capable of reversible changes in shape, i.e., four-dimensional-printed structures, may enable new generations of soft robotics, implantable medical devices, and consumer products. Here, thermally responsive liquid crystal elastomers (LCEs) are direct-write printed into 3D structures with a controlled molecular order. Molecular order is locally programmed by controlling the print path used to build the 3D object, and this order controls the stimulus response. Each aligned LCE filament undergoes 40% reversible contraction along the print direction on heating. By printing objects with controlled geometry and stimulus response, magnified shape transformations, for example, volumetric contractions or rapid, repetitive snap-through transitions, are realized.
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Affiliation(s)
- Cedric P Ambulo
- Department of Bioengineering, The University of Texas at Dallas , Richardson, Texas 75080, United States
| | - Julia J Burroughs
- Department of Bioengineering, The University of Texas at Dallas , Richardson, Texas 75080, United States
| | - Jennifer M Boothby
- Department of Bioengineering, The University of Texas at Dallas , Richardson, Texas 75080, United States
| | - Hyun Kim
- Department of Bioengineering, The University of Texas at Dallas , Richardson, Texas 75080, United States
| | - M Ravi Shankar
- Department of Industrial Engineering, The University of Pittsburgh , Pittsburgh, Pennsylvania 15261, United States
| | - Taylor H Ware
- Department of Bioengineering, The University of Texas at Dallas , Richardson, Texas 75080, United States
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20
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Xia Y, Cedillo-Servin G, Kamien RD, Yang S. Guided Folding of Nematic Liquid Crystal Elastomer Sheets into 3D via Patterned 1D Microchannels. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2016; 28:9637-9643. [PMID: 27717070 DOI: 10.1002/adma.201603751] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 08/05/2016] [Indexed: 05/23/2023]
Abstract
Two-dimensional liquid-crystal elastomer (LCE) sheets with preprogrammed topological defects are prepared by aligning liquid-crystal monomers within micropatterned epoxy channels, followed by photopolymerization. Upon heating, the LCE films form various three-dimensional structures in agreement with theoretical design. The miniaturized LCE actuators offer large-area work capacities (≈1.05 J m-2 ) to lift over 700 times their own weight.
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Affiliation(s)
- Yu Xia
- Department of Materials Science and Engineering, University of Pennsylvania, 3231 Walnut Street, Philadelphia, PA, 19104, USA
| | - Gerardo Cedillo-Servin
- Department of Materials Science and Engineering, University of Pennsylvania, 3231 Walnut Street, Philadelphia, PA, 19104, USA
| | - Randall D Kamien
- Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd St, Philadelphia, PA, 19104, USA
| | - Shu Yang
- Department of Materials Science and Engineering, University of Pennsylvania, 3231 Walnut Street, Philadelphia, PA, 19104, USA
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21
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Plucinsky P, Lemm M, Bhattacharya K. Programming complex shapes in thin nematic elastomer and glass sheets. Phys Rev E 2016; 94:010701. [PMID: 27575067 DOI: 10.1103/physreve.94.010701] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Indexed: 11/07/2022]
Abstract
Nematic elastomers and glasses are solids that display spontaneous distortion under external stimuli. Recent advances in the synthesis of sheets with controlled heterogeneities have enabled their actuation into nontrivial shapes with unprecedented energy density. Thus, these have emerged as powerful candidates for soft actuators. To further this potential, we introduce the key metric constraint which governs shape-changing actuation in these sheets. We then highlight the richness of shapes amenable to this constraint through two broad classes of examples which we term nonisometric origami and lifted surfaces. Finally, we comment on the derivation of the metric constraint, which arises from energy minimization in the interplay of stretching, bending, and heterogeneity in these sheets.
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Affiliation(s)
- Paul Plucinsky
- Engineering and Applied Science, California Institute of Technology, Pasadena, California 91125, USA
| | - Marius Lemm
- Department of Mathematics, California Institute of Technology, Pasadena, California 91125, USA
| | - Kaushik Bhattacharya
- Engineering and Applied Science, California Institute of Technology, Pasadena, California 91125, USA
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22
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Chung H, Choi J, Yun JH, Cho M. Nonlinear photomechanics of nematic networks: upscaling microscopic behaviour to macroscopic deformation. Sci Rep 2016; 6:20026. [PMID: 26828417 PMCID: PMC4734330 DOI: 10.1038/srep20026] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 12/08/2015] [Indexed: 11/29/2022] Open
Abstract
A liquid crystal network whose chromophores are functionalized by photochromic dye exhibits light-induced mechanical behaviour. As a result, the micro-scaled thermotropic traits of the network and the macroscopic phase behaviour are both influenced as light alternates the shape of the dyes. In this paper, we present an analysis of this photomechanical behaviour based on the proposed multiscale framework, which incorporates the molecular details of microstate evolution into a continuum-based understanding. The effects of trans-to-cis photoisomerization driven by actinic light irradiation are first examined using molecular dynamics simulations, and are compared against the predictions of the classical dilution model; this reveals certain characteristics of mesogenic interaction upon isomerization, followed by changes in the polymeric structure. We then upscale the thermotropic phase-related information with the aid of a nonlinear finite element analysis; macroscopic deflection with respect to the wide ranges of temperature and actinic light intensity are thereby examined, which reveals that the classical model underestimates the true deformation. This work therefore provides measures for analysing photomechanics in general by bridging the gap between the micro- and macro-scales.
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Affiliation(s)
- Hayoung Chung
- School of Mechanical and Aerospace Engineering, Seoul National University, Seoul, 151-744, South Korea
| | - Joonmyung Choi
- School of Mechanical and Aerospace Engineering, Seoul National University, Seoul, 151-744, South Korea
| | - Jung-Hoon Yun
- School of Mechanical and Aerospace Engineering, Seoul National University, Seoul, 151-744, South Korea
| | - Maenghyo Cho
- School of Mechanical and Aerospace Engineering, Seoul National University, Seoul, 151-744, South Korea
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23
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Aharoni H, Sharon E, Kupferman R. Geometry of thin nematic elastomer sheets. PHYSICAL REVIEW LETTERS 2014; 113:257801. [PMID: 25554907 DOI: 10.1103/physrevlett.113.257801] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Indexed: 06/04/2023]
Abstract
A thin sheet of nematic elastomer attains 3D configurations depending on the nematic director field upon heating. In this Letter, we describe the intrinsic geometry of such a sheet and derive an expression for the metric induced by general nematic director fields. Furthermore, we investigate the reverse problem of constructing a director field that induces a specified 2D geometry. We provide an explicit recipe for how to construct any surface of revolution using this method. Finally, we show that by inscribing a director field gradient across the sheet's thickness, one can obtain a nontrivial hyperbolic reference curvature tensor, which together with the prescription of a reference metric allows dictation of actual configurations for a thin sheet of nematic elastomer.
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Affiliation(s)
- Hillel Aharoni
- Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Eran Sharon
- Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Raz Kupferman
- Institute of Mathematics, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
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24
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Liu D, Broer DJ. Liquid crystal polymer networks: preparation, properties, and applications of films with patterned molecular alignment. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:13499-509. [PMID: 24707811 DOI: 10.1021/la500454d] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Monolithically ordered liquid crystal polymer networks are formed by the photoinitiated polymerization of multifunctional liquid crystal monomers. This paper describes the relevant principles and methods, the basic structure-property relationships in terms of mesogenic properties of the monomers, and the mechanical and optical properties of the polymers. Strategies are discussed to control the molecular orientation by various means and in all three dimensions. The versatility of the process is demonstrated by two examples of films with a patterned molecular order. It is shown that patterned retarders can be made by a two-step polymerization process which is successfully employed in a transflective display principle. A transflective display is a liquid crystal display that operates in both a reflective mode using ambient light and a transmissive mode with light coming from a backlight system. Furthermore, a method is discussed to create a patterned film in a single polymerization process. This film has alternating planar chiral nematic areas next to perpendicularly oriented (so-called homeotropic) areas. When applied as a coating to a substrate, the film changes its surface texture. During exposure to UV light, it switches from a flat to a corrugated state.
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Affiliation(s)
- Danqing Liu
- Laboratory of Functional Organic Materials & Devices (SFD), Department of Chemical Engineering & Chemistry, Eindhoven University of Technology , Den Dolech 2, 5612 AZ Eindhoven, The Netherlands
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25
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26
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Liu D, Broer DJ. Light controlled friction at a liquid crystal polymer coating with switchable patterning. SOFT MATTER 2014; 10:7952-8. [PMID: 25154768 DOI: 10.1039/c4sm01249f] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
We describe a new methodology that enables dynamical control of motion through modulating the friction at coating surfaces by exposing to UV light. The principle is based on reversible switching of the surface topographies of the coating by light. The coating surface transfers from flat in the dark to corrugated in the presence of UV by forming regular ridge-like line gratings. Both the static and the kinetic friction coefficient are investigated in a dynamic manner by switching between the off (flat surface) and the activated (with ridges) state. By dynamically changing the friction, we are able to bring the sample from a static state into motion via UV exposure. When in motion, the friction coefficient can be altered further by modulating the light conditions. For example, a smooth sliding can transfer into an interlocking state, or vice versa. Moreover, we can dynamically reduce the contact area in the interface and thus lowering friction forces.
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Affiliation(s)
- Danqing Liu
- Group Functional Organic Materials & Devices (SFD), Department of Chemical Engineering & Chemistry, Eindhoven University of Technology, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands
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27
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Liu D, Broer DJ. Self-assembled Dynamic 3D Fingerprints in Liquid-Crystal Coatings Towards Controllable Friction and Adhesion. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201400370] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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28
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Liu D, Broer DJ. Self-assembled Dynamic 3D Fingerprints in Liquid-Crystal Coatings Towards Controllable Friction and Adhesion. Angew Chem Int Ed Engl 2014; 53:4542-6. [PMID: 24615907 DOI: 10.1002/anie.201400370] [Citation(s) in RCA: 124] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Indexed: 11/11/2022]
Affiliation(s)
- Danqing Liu
- Laboratory of Functional Organic Materials & Devices (SFD), Department of Chemical Engineering & Chemistry, Eindhoven University of Technology, Den Dolech 2, 5612 AZ Eindhoven (The Netherlands)
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29
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He LH. Response of constrained glassy splay-bend and twist nematic sheets to light and heat. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2013; 36:83. [PMID: 23921449 DOI: 10.1140/epje/i2013-13083-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2013] [Revised: 06/09/2013] [Accepted: 06/11/2013] [Indexed: 06/02/2023]
Abstract
A general approach is proposed to analyze the complex photo- or thermo-response of glassy splay-bend and twist nematic sheets with boundary constraints. The governing equations are two-dimensional, as in the classical plate theory. However, the solution can generate exact three-dimensional displacement and stress distributions within the interior of the sheets, except the boundary layer whose width is of the same order of the sheet thickness.
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Affiliation(s)
- L H He
- CAS Key Laboratory of Mechanical Behavior and Design of Materials, University of Science and Technology of China, 230026 Hefei, Anhui, P.R. China.
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30
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Modes CD, Warner M, Sánchez-Somolinos C, de Haan LT, Broer D. Mechanical frustration and spontaneous polygonal folding in active nematic sheets. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 86:060701. [PMID: 23367885 DOI: 10.1103/physreve.86.060701] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Indexed: 06/01/2023]
Abstract
We analyze the bending response to light or heat of a solid nematic disk with a director twisted from being radial on the upper surface to be azimuthal on the lower. We find a number of curl lobes determined purely by the geometry of the mechanical frustration that arises during the response.
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Affiliation(s)
- C D Modes
- Laboratory of Mathematical Physics, The Rockefeller University, 1230 York Avenue, New York, New York 10065, USA
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31
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Lee KM, White TJ. Photochemical Mechanism and Photothermal Considerations in the Mechanical Response of Monodomain, Azobenzene-Functionalized Liquid Crystal Polymer Networks. Macromolecules 2012. [DOI: 10.1021/ma301337e] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Kyung Min Lee
- Employed by Azimuth Corporation, 4134 Linden Avenue, Dayton, Ohio 45432,
United States
| | - Timothy J. White
- Materials and Manufacturing Directorate, Air Force Research Laboratory, 3005 Hobson Way Ste.
1, Wright-Patterson Air Force Base, Ohio 45433, United States
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32
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Lee KM, Tabiryan NV, Bunning TJ, White TJ. Photomechanical mechanism and structure-property considerations in the generation of photomechanical work in glassy, azobenzene liquid crystal polymer networks. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c1jm14017e] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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33
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Modes CD, Warner M. Blueprinting nematic glass: systematically constructing and combining active points of curvature for emergent morphology. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 84:021711. [PMID: 21929008 DOI: 10.1103/physreve.84.021711] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2011] [Indexed: 05/22/2023]
Abstract
Much recent progress has been made in the study of nematic solids, both glassy and elastomeric, particularly in the realm of stress-free, defect-driven deformation in thin sheets of material. In this paper we consider a subset of texture domains in nematic glasses that are simple to synthesize, and explore the ways that these simple domains may be compatibly combined to yield analogs of the traditional smooth disclination defect textures seen in standard liquid crystals. We calculate the deformation properties of these constructed textures, and show that, subject to the compatibility constraints of the construction, these textures may be further combined to achieve shape blueprinting of three-dimensional structures from flat sheets.
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Affiliation(s)
- C D Modes
- Cavendish Laboratory, University of Cambridge, 19 JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
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34
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Modes CD, Bhattacharya K, Warner M. Gaussian curvature from flat elastica sheets. Proc Math Phys Eng Sci 2010. [DOI: 10.1098/rspa.2010.0352] [Citation(s) in RCA: 119] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
We discuss methods of reversibly inducing non-developable surfaces from flat sheets of material at the micro-scale all the way to macroscopic objects. We analyse the elastic ground states of a nematic glass in the membrane approximation as a function of temperature for disclination defects of topological charge +1. An aim is to show that by writing an appropriate director field into such a solid, one could create a surface with Gaussian curvature, dynamically switchable from flat sheets while avoiding stretch energy. In addition to the prospect of programmable structures, such surfaces offer actuation via stretch in thin systems since when illumination is subsequently removed, unavoidable stretches return.
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Affiliation(s)
- C. D. Modes
- Cavendish Laboratory, University of Cambridge, 19 JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - K. Bhattacharya
- Division of Engineering and Applied Science, California Institute of Technology, Pasadena, CA 91125, USA
| | - M. Warner
- Cavendish Laboratory, University of Cambridge, 19 JJ Thomson Avenue, Cambridge CB3 0HE, UK
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35
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Modes CD, Warner M, van Oosten CL, Corbett D. Anisotropic response of glassy splay-bend and twist nematic cantilevers to light and heat. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 82:041111. [PMID: 21230242 DOI: 10.1103/physreve.82.041111] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2010] [Revised: 08/25/2010] [Indexed: 05/30/2023]
Abstract
A gradient of director through the thickness of a nematic glass cantilever gives a gradient in the large distortions such materials suffer in response to temperature or illumination changes. We first sketch, within isotropic elasticity, how such gradients cause these cantilevers to respond by bending. We then derive the response within the anisotropic elasticity expected for uniaxial solids. Because, in general, spontaneously bending cantilevers have regions of elongation and contraction (with respect to their neutral state), internal stresses are generated, the magnitude of which depends on the anisotropic, fourth rank modulus tensor and in particular on its local alignment arising from the director's spatial distribution. We show that despite elastic complexity, bend is simply linear in the anisotropy of thermo-optical response, with a slope depending on the structure of the modulus tensor, justifying the previous literature on spontaneously bending cantilevers. We also explicitly consider two important director distributions--splay-bend and twist. Splay-bend cantilevers have no anticlastic (double-bend, saddle) response in the isotropic case or for some values of the anisotropic modulus tensor. Twist cantilevers have maximal anticlasticity in the isotropic case which we show to be weakly modified by anisotropy of elastic moduli.
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Affiliation(s)
- C D Modes
- Cavendish Laboratory, University of Cambridge, 19 JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
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