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You Y, Golestani YM, Broer DJ, Yang T, Zhou G, Selinger RLB, Yuan D, Liu D. Transforming patterned defects into dynamic poly-regional topographies in liquid crystal oligomers. MATERIALS HORIZONS 2024; 11:3178-3186. [PMID: 38666445 PMCID: PMC11216033 DOI: 10.1039/d4mh00131a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Accepted: 04/18/2024] [Indexed: 07/02/2024]
Abstract
We create high-aspect-ratio dynamic poly-regional surface topographies in a coating of a main-chain liquid crystal oligomer network (LCON). The topographies form at the topological defects in the director pattern organized in an array which are controlled by photopatterning of the alignment layer. The defect regions are activated by heat and/or light irradiation to form reversible topographic structures. Intrinsically, the LCON is rubbery and sensitive to temperature changes, resulting in shape transformations. We further advanced such system to make it light-responsive by incorporating azobenzene moieties. Actuation reduces the molecular order of the LCON coating that remains firmly adhered to the substrate which gives directional shear stresses around the topological defects. The stresses relax by deforming the surfaces by forming elevations or indents, depending on the type of defects. The formed topographies exhibit various features, including two types of protrusions, ridges and valleys. These poly-regional structures exhibit a large modulation amplitude of close to 60%, which is 6 times larger than the ones formed in liquid crystal networks (LCNs). After cooling or by blue light irradiation, the topographies are erased to the initial flat surface. A finite element method (FEM) model is adopted to simulate structures of surface topographies. These dynamic surface topographies with multilevel textures and large amplitude expand the application range, from haptics, controlled cell growth, to intelligent surfaces with adjustable adhesion and tribology.
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Affiliation(s)
- Yuxin You
- Joint Research Lab of Devices Integrated Responsive Materials (DIRM), South China Normal University, Guangzhou 510006, China.
- Human Interactive Materials (HIM), Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Groene Loper 3, Eindhoven 5612AE, The Netherlands.
- Institute for Complex Molecular Systems (ICMS), Eindhoven University of Technology, Groene Loper 3, Eindhoven 5612AE, The Netherlands
| | - Youssef M Golestani
- Human Interactive Materials (HIM), Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Groene Loper 3, Eindhoven 5612AE, The Netherlands.
- Institute for Complex Molecular Systems (ICMS), Eindhoven University of Technology, Groene Loper 3, Eindhoven 5612AE, The Netherlands
| | - Dirk J Broer
- Human Interactive Materials (HIM), Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Groene Loper 3, Eindhoven 5612AE, The Netherlands.
- Institute for Complex Molecular Systems (ICMS), Eindhoven University of Technology, Groene Loper 3, Eindhoven 5612AE, The Netherlands
| | - Tinghong Yang
- Joint Research Lab of Devices Integrated Responsive Materials (DIRM), South China Normal University, Guangzhou 510006, China.
| | - Guofu Zhou
- Joint Research Lab of Devices Integrated Responsive Materials (DIRM), South China Normal University, Guangzhou 510006, China.
| | - Robin L B Selinger
- Department of Physics, Kent State University, Kent, OH 44242, USA.
- Advanced Materials and Liquid Crystal Institute, Kent State University, Kent, OH 44242, USA
| | - Dong Yuan
- Joint Research Lab of Devices Integrated Responsive Materials (DIRM), South China Normal University, Guangzhou 510006, China.
| | - Danqing Liu
- Human Interactive Materials (HIM), Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Groene Loper 3, Eindhoven 5612AE, The Netherlands.
- Institute for Complex Molecular Systems (ICMS), Eindhoven University of Technology, Groene Loper 3, Eindhoven 5612AE, The Netherlands
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2
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Schlafmann KR, Alahmed MS, Pearl HM, White TJ. Tunable and Switchable Thermochromism in Cholesteric Liquid Crystalline Elastomers. ACS APPLIED MATERIALS & INTERFACES 2024. [PMID: 38669605 DOI: 10.1021/acsami.3c18367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/28/2024]
Abstract
Thermochromic materials have found widespread commercial use in packaging as temperature indicators. Often, these products utilize leuco dyes that are mixed into conventional polymeric resins to prepare coatings or films that exhibit temperature-dependent color change. Here, we consider a distinctive approach to thermochromism via the selective reflection of liquid crystalline elastomers that retain the helicoidal structure of the cholesteric phase (CLCEs). Upon heating, the order of the CLCEs reduces and approaches zero, resulting in a change in birefringence as well as material thickness, both of which manifest as changes in the selective reflection to heating. This examination systematically prepares CLCEs capable of reversible thermochromic response as a function of cross-link density and liquid crystalline composition. A particular focus of this examination is the preparation of CLCEs composed of chiral and achiral liquid crystalline monomers that reduce the strength of the mesogen-mesogen interaction and accordingly reduce the nematic-isotropic transition temperature. The low birefringence of some of the CLCE compositions facilitates thermochromic reflection tuning, followed by switching.
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Affiliation(s)
- Kyle R Schlafmann
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80303, United States
| | - Mohammed S Alahmed
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80303, United States
| | - Harrison M Pearl
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80303, United States
| | - Timothy J White
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80303, United States
- Materials Science and Engineering Program, University of Colorado Boulder, Boulder Colorado 80303, United States
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3
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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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4
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Tabrizi M, Clement JA, Babaei M, Martinez A, Gao J, Ware TH, Shankar MR. Three-dimensional blueprinting of molecular patterns in liquid crystalline polymers. SOFT MATTER 2024; 20:511-522. [PMID: 38113054 DOI: 10.1039/d3sm01374j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2023]
Abstract
Exploiting the interplay of anisotropic diamagnetic susceptibility of liquid crystalline monomers and site selective photopolymerization enables the fabrication of 3D freeforms with highly refined microstructures. Utilizing chain transfer agents in the mesogenic inks presents a pathway for broadly tuning the mechanical properties of liquid crystalline polymers and their response to stimuli. In particular, the combination of 1,4-benzenedimethanethiol and tetrabromomethane is shown to enable voxelated blueprinting of molecular order, while allowing for a modulation of the crosslink density and the mechanical properties. The formulation of these monomers allows for the resolution of the voxels to approach the limits set by the coherence lengths defined by the anchoring from surfaces. These compositions demonstrate the expected thermotropic responses while allowing for their functionalization with photochromic switches to elicit photomechanical responses. Actuation strains are shown to outstrip that accomplished with prior systems that did not access chain transfer agents to modulate the structure of the macromolecular network. Test cases of this system are shown to create freeform actuators that exploit the refined director patterns during high-resolution printing. These include topological defects, hierarchically-structured light responsive grippers, and biomimetic flyers whose flight dynamics can be actively modulated via irradiation with light.
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Affiliation(s)
- Mohsen Tabrizi
- Department of Industrial Engineering, Swanson School of Engineering, University of Pittsburgh, PA 15261, USA.
| | - J Arul Clement
- Department of Industrial Engineering, Swanson School of Engineering, University of Pittsburgh, PA 15261, USA.
| | - Mahnoush Babaei
- Department of Aerospace Engineering & Engineering Mechanics, University of Texas at Austin, 2617 Wichita Street, C0600, Austin, TX 78712, USA.
| | - Angel Martinez
- Department of Applied Physics and Materials Science, Northern Arizona University, Science Annex, 525 S Beaver St, Flagstaff, AZ 86011, USA.
| | - Junfeng Gao
- Department of Industrial Engineering, Swanson School of Engineering, University of Pittsburgh, PA 15261, USA.
| | - Taylor H Ware
- Department of Biomedical Engineering, Texas A&M University, 101 Bizzell Street, College Station, TX 77843, USA
- Department of Materials Science and Engineering, Texas A&M University, 209 Reed McDonald Building, College Station, TX 77843, USA.
| | - M Ravi Shankar
- Department of Industrial Engineering, Swanson School of Engineering, University of Pittsburgh, PA 15261, USA.
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5
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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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6
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Bao J, Wang Z, Song C, Zhang Y, Li Z, Zhang L, Lan R, Yang H. Shape-Programmable Liquid-Crystalline Polyurethane-Based Multimode Actuators Triggered by Light-Driven Molecular Motors. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2302168. [PMID: 37459653 DOI: 10.1002/adma.202302168] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 06/08/2023] [Accepted: 06/29/2023] [Indexed: 09/03/2023]
Abstract
In recent years, light-driven soft actuators have been rapidly developed as enablers in the fabrication of artificial robots and biomimetic devices. However, it remains challenging to amplify molecular isomerization to multiple modes of macroscopic actuation with large amplitude and complex motions. Here, a strategy is reported to build a light-responsive liquid-crystalline polyurethane elastomer by phototriggered overcrowded alkene-based molecular motors. A trifunctional molecular motor modified with an ethylene glycol spacer on the rotor and stator functions as a crosslinker and unidirectional stirrer that amplifies molecular motion into macroscopic movement. The shape-programmable polymeric film presents superior mechanical properties and characteristic shape-memory effect. Furthermore, diverse modes of motions including bending, unwinding, and contracting with tunable actuation speed over a wide range are achieved. Such research is hoped to pave a new way for the design of advanced light-responsive soft actuators and robots.
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Affiliation(s)
- Jinying Bao
- Beijing Advanced Innovation Center for Materials Genome Engineering & School of Materials Science and Engineering, Peking University, Beijing, 100871, P. R. China
| | - Zizheng Wang
- Beijing Advanced Innovation Center for Materials Genome Engineering & School of Materials Science and Engineering, Peking University, Beijing, 100871, P. R. China
| | - Chenjie Song
- Capital Medical University, Beijing Anzhen Hospital, Department of Ophthalmology, Beijing, 100029, P. R. China
| | - Yuhan Zhang
- School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Zhaozhong Li
- School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Lanying Zhang
- Beijing Advanced Innovation Center for Materials Genome Engineering & School of Materials Science and Engineering, Peking University, Beijing, 100871, P. R. China
- Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, Peking University, Beijing, 100871, P. R. China
| | - Ruochen Lan
- Beijing Advanced Innovation Center for Materials Genome Engineering & School of Materials Science and Engineering, Peking University, Beijing, 100871, P. R. China
- Institute of Advanced Materials, Jiangxi Normal University, Nanchang, 330022, China
| | - Huai Yang
- Beijing Advanced Innovation Center for Materials Genome Engineering & School of Materials Science and Engineering, Peking University, Beijing, 100871, P. R. China
- Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, Peking University, Beijing, 100871, P. R. China
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7
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Lewis KL, Herbert KM, Matavulj VM, Hoang JD, Ellison ET, Bauman GE, Herman JA, White TJ. Programming Orientation in Liquid Crystalline Elastomers Prepared with Intra-Mesogenic Supramolecular Bonds. ACS APPLIED MATERIALS & INTERFACES 2023; 15:3467-3475. [PMID: 36598490 DOI: 10.1021/acsami.2c18993] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
The large, directional stimuli-response of aligned liquid crystalline elastomers (LCEs) could enable functional utility in robotics, medicine, consumer goods, and photonics. The alignment of LCEs has historically been realized via mechanical alignment of a two-stage reaction. Recent reports widely utilize chain extension reactions of liquid crystal monomers (LCM) to form LCEs that are subject to either surface-enforced or mechanical alignment. Here, we prepare LCEs that contain intra-mesogenic supramolecular bonds synthesized via direct free-radical chain transfer photopolymerization processible by a distinctive mechanical alignment mechanism. The LCEs were prepared by the polymerization of a benzoic acid monomer (11OBA), which dimerized to form a liquid crystal monomer, with a diacrylate LCM (C6M). The incorporation of the intra-mesogenic hydrogen bonds increases the achievable nematic order from mechanical programming. Accordingly, LCEs prepared with larger 11OBA concentration exhibit higher magnitude thermomechanical strain values when compared to a LCE containing only covalent bonds. These LCEs can be reprogrammed with heat to return the aligned film to the polydomain state. The LCE can then be subsequently programmed to orient in a different direction. The facile preparation of (re)programmable LCEs with supramolecular bonds opens new avenues for the implementation of these materials as shape deployable elements.
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Affiliation(s)
- Kristin L Lewis
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado80309, United States
| | - Katie M Herbert
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado80309, United States
| | - Valentina M Matavulj
- Material Science and Engineering Program, University of Colorado Boulder, Boulder, Colorado80309, United States
| | - Jonathan D Hoang
- Material Science and Engineering Program, University of Colorado Boulder, Boulder, Colorado80309, United States
| | - Eric T Ellison
- Department of Geological Sciences, University of Colorado Boulder, Boulder, Colorado80309, United States
| | - Grant E Bauman
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado80309, United States
| | - Jeremy A Herman
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado80309, United States
| | - Timothy J White
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado80309, United States
- Material Science and Engineering Program, University of Colorado Boulder, Boulder, Colorado80309, United States
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8
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Ahmadpour-Samani P, Zahedi P. An investigation on nematic-isotropic phase transition, viscosity and diffusion coefficient of liquid crystalline elastomers at different temperatures using molecular dynamics simulation. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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9
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Abadia AV, Herbert KM, White TJ, Schwartz DK, Kaar JL. Biocatalytic 3D Actuation in Liquid Crystal Elastomers via Enzyme Patterning. ACS APPLIED MATERIALS & INTERFACES 2022; 14:26480-26488. [PMID: 35652291 DOI: 10.1021/acsami.2c05802] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Liquid crystal elastomers (LCEs) are stimuli-responsive materials that undergo large shape transformations after undergoing an order-disorder transition. While shape reconfigurations in LCEs are predominantly triggered by heat, there is a considerable interest in developing highly specific triggers that work at room temperature. Herein, we report the fabrication of biocatalytic LCEs that respond to the presence of urea by covalently immobilizing urease within chemically responsive LCE networks. The hydrogen-bonded LCEs developed in this work exhibited contractile strains of up to 36% upon exposure to a base. Notably, the generation of ammonia by immobilized urease triggered a disruption in the supramolecular network and a large reduction of liquid crystalline order in the films when the LCEs were exposed to urea. This reduction in order was macroscopically translated into a strain response that could be modulated by changing the concentration of urea or exposure time to the substrate. Local control of the mechanical response of the LCE was realized by spatially patterning the enzyme on the surface of the films. Subsequent exposure of enzymatically patterned LCE to urea-triggered 3D shape transformations into a curl, arch, or accordion-like structure, depending on the motif patterned on the film surface. Furthermore, we showed that the presence of salt was critical to prevent bridging of the network by the presence of ammonium ions, thereby enabling such macroscopic 3D shape changes. The large actuation potential of LCEs and the ability to translate the biocatalytic activity of enzymes to macroscopic 3D shape transformations could enable use in applications ranging from cell culture, medicine, or antifouling.
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Affiliation(s)
- Albert Velasco Abadia
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309, United States
| | - Katie M Herbert
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309, United States
| | - Timothy J White
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309, United States
- Material Science and Engineering, University of Colorado, Boulder, Colorado 80309, United States
| | - Daniel K Schwartz
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309, United States
| | - Joel L Kaar
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309, United States
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10
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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: 8] [Impact Index Per Article: 4.0] [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.
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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
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11
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Foelen Y, van Gils NJM, Claessen MDT, Schenning APHJ. Multicolor photonic patterns through an intensity-controlled single photopolymerization step. Chem Commun (Camb) 2022; 58:10833-10836. [PMID: 36069648 PMCID: PMC9514011 DOI: 10.1039/d2cc04050f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
The UV intensity during photopolymerization allows control over the structural color of a cholesteric liquid crystal (CLC) polymer photonic coating in a single step. Simultaneously, the glass transition temperature (Tg) of the polymer can be tuned by the applied UV intensity. Most likely the low intensity photopolymerization increases the inhibition time, leading to in situ formation of polymer fragments through oxygen inhibition. The formation of polymer fragments changes the matrix during the inhibition time, which results in a color change before the polymer network is formed. Additionally, these fragments inside the network act as a plasticizer, effectively lowering the Tg. This method can be combined with temperature responsive properties based on shape memory to fabricate photonic coatings with multiple, responsive colored patterns. The presented work allows for new functionalities in responsive photonic polymers as multiple colors and response temperatures can be incorporated in a single polymerization step. The UV intensity during photopolymerization allows control over the structural color of a cholesteric liquid crystal (CLC) polymer photonic coating in a single step.![]()
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Affiliation(s)
- Yari Foelen
- Stimuli-responsive Functional Materials and Devices, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands.
- Institute for Complex Molecular Systems, Eindhoven University of Technology, Den Dolech 2, 5600 MB, Eindhoven, The Netherlands
| | - Nieké J M van Gils
- Stimuli-responsive Functional Materials and Devices, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands.
| | - Mart D T Claessen
- Stimuli-responsive Functional Materials and Devices, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands.
| | - Albertus P H J Schenning
- Stimuli-responsive Functional Materials and Devices, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands.
- Institute for Complex Molecular Systems, Eindhoven University of Technology, Den Dolech 2, 5600 MB, Eindhoven, The Netherlands
- SCNU-TUE Joint Laboratory of Device Integrated Responsive Materials (DIRM), South China Normal University, Guangzhou Higher Education Mega Center, 510006, Guangzhou, China
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12
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Weder C. ACS Macro Letters - Your Go-To Journal for Research on Stimuli-Responsive Polymers. ACS Macro Lett 2021; 10:1450-1453. [PMID: 35549013 DOI: 10.1021/acsmacrolett.1c00679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Christoph Weder
- Polymer Chemistry and Materials, the Adolphe Merkle Institute, Université de Fribourg, Chemin des Verdiers 4, 1700 Fribourg, Switzerland
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13
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Hebner TS, Fowler HE, Herbert KM, Skillin NP, Bowman CN, White TJ. Polymer Network Structure, Properties, and Formation of Liquid Crystalline Elastomers Prepared via Thiol–Acrylate Chain Transfer Reactions. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c01919] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Tayler S. Hebner
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Hayden E. Fowler
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Katie M. Herbert
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Nathaniel P. Skillin
- Department of Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Christopher N. Bowman
- 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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14
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Fowler HE, Rothemund P, Keplinger C, White TJ. Liquid Crystal Elastomers with Enhanced Directional Actuation to Electric Fields. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2103806. [PMID: 34510561 DOI: 10.1002/adma.202103806] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 08/04/2021] [Indexed: 06/13/2023]
Abstract
The integration of soft, stimuli-responsive materials in robotic systems is a promising approach to introduce dexterous and delicate manipulation of objects. Electrical control of mechanical response offers many benefits in robotic systems including the availability of this energy input, the associated response time, magnitude of actuation, and opportunity for self-regulation. Here, a materials chemistry is detailed to prepare liquid crystal elastomers (LCEs) with a 14:1 modulus contrast and increase in dielectric constant to enhance electromechanical deformation. The inherent modulus contrast of these LCEs (when coated with compliant electrodes) directly convert an electric field to a directional expansion of 20%. The electromechanical response of LCE actuators is observed upon application of voltage ranging from 0.5 to 6 kV. The deformation of these materials is rapid, reaching strain rates of 18% s-1 . Upon removal of the electric field, little hysteresis is observed. Patterning the spatial orientation of the nematic director of the LCEs results in a 2D-3D shape transformation to a cone 8 mm in height. Individual and sequential addressing of an array of LCE actuators is demonstrated as a haptic surface.
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Affiliation(s)
- Hayden E Fowler
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, Boulder, CO, 80309, USA
| | - Philipp Rothemund
- Department of Mechanical Engineering, University of Colorado, Boulder, Boulder, CO, 80309, USA
- Robotic Materials Department, Max Planck Institute for Intelligent Systems, Stuttgart, 70569, Germany
| | - Christoph Keplinger
- Department of Mechanical Engineering, University of Colorado, Boulder, Boulder, CO, 80309, USA
- Robotic Materials Department, Max Planck Institute for Intelligent Systems, Stuttgart, 70569, Germany
- Materials Science and Engineering Program, University of Colorado, Boulder, Boulder, CO, 80309, USA
| | - Timothy J White
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, Boulder, CO, 80309, USA
- Materials Science and Engineering Program, University of Colorado, Boulder, Boulder, CO, 80309, USA
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15
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Schlafmann KR, White TJ. Retention and deformation of the blue phases in liquid crystalline elastomers. Nat Commun 2021; 12:4916. [PMID: 34389708 PMCID: PMC8363666 DOI: 10.1038/s41467-021-25112-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Accepted: 07/16/2021] [Indexed: 12/03/2022] Open
Abstract
The blue phases are observed in highly chiral liquid crystalline compositions that nascently organize into a three-dimensional, crystalline nanostructure. The periodicity of the unit cell lattice spacing is on the order of the wavelength of visible light and accordingly, the blue phases exhibit a selective reflection as a photonic crystal. Here, we detail the synthesis of liquid crystalline elastomers that retain blue phase I, blue phase II, and blue phase III. The mechanical properties and optical reconfiguration via deformation of retained blue phases are contrasted to the cholesteric phase in fully solid elastomers with glass transition temperatures below room temperature. Mechanical deformation and chemical swelling of the lightly crosslinked polymer networks induces lattice asymmetry in the blue phase evident in the tuning of the selective reflection. The lattice periodicity of the blue phase elastomer is minimally affected by temperature. The oblique lattice planes of the blue phase tilt and red-shift in response to mechanical deformation. The retention of the blue phases in fully solid, elastomeric films could enable functional implementations in photonics, sensing, and energy applications.
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Affiliation(s)
- Kyle R Schlafmann
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, CO, USA
| | - Timothy J White
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, CO, USA.
- Department of Materials Science and Engineering, University of Colorado, Boulder, CO, USA.
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16
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Kim K, Guo Y, Bae J, Choi S, Song HY, Park S, Hyun K, Ahn SK. 4D Printing of Hygroscopic Liquid Crystal Elastomer Actuators. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 17:e2100910. [PMID: 33938152 DOI: 10.1002/smll.202100910] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Revised: 03/16/2021] [Indexed: 06/12/2023]
Abstract
Liquid crystal elastomers (LCEs) are broadly recognized as programmable actuating materials that are responsive to external stimuli, typically heat or light. Yet, soft LCEs that respond to changes in environmental humidity are not reported, except a few examples based on rigid liquid crystal networks with limited processing. Herein, a new class of highly deformable hygroscopic LCE actuators that can be prepared by versatile processing methods, including surface alignment as well as 3D printing is presented. The dimethylamino-functionalized LCE is prepared by the aza-Michael addition reaction between a reactive LC monomer and N,N'-dimethylethylenediamine as a chain extender, followed by photopolymerization. The humidity-responsive properties are introduced by activating one of the LCE surfaces with an acidic solution, which generates cations on the surface and provides asymmetric hydrophilicity to the LCE. The resulting humidity-responsive LCE undergoes programmed and reversible hygroscopic actuation, and its shape transformation can be directed by the cut angle with respect to a nematic director or by localizing activation regions in the LCE. Most importantly, various hygroscopic LCE actuators, including (porous) bilayers, a flower, a concentric square array, and a soft gripper, are successfully fabricated by using LC inks in UV-assisted direct-ink-writing-based 3D printing.
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Affiliation(s)
- Keumbee Kim
- Department of Polymer Science and Engineering, Pusan National University, Busan, 46241, Republic of Korea
| | - Yuanhang Guo
- Department of Polymer Science and Engineering, Pusan National University, Busan, 46241, Republic of Korea
| | - Jaehee Bae
- Department of Polymer Science and Engineering, Pusan National University, Busan, 46241, Republic of Korea
| | - Subi Choi
- Department of Polymer Science and Engineering, Pusan National University, Busan, 46241, Republic of Korea
| | - Hyeong Yong Song
- Institute for Environment and Energy, Pusan National University, Busan, 46241, Republic of Korea
- School of Chemical Engineering, Pusan National University, Busan, 46241, Republic of Korea
| | - Sungmin Park
- Advanced Materials Division, Korea Research Institute of Chemical Technology, Daejeon, 34114, Republic of Korea
| | - Kyu Hyun
- School of Chemical Engineering, Pusan National University, Busan, 46241, Republic of Korea
| | - Suk-Kyun Ahn
- Department of Polymer Science and Engineering, Pusan National University, Busan, 46241, Republic of Korea
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17
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Tokumoto H, Zhou H, Takebe A, Kamitani K, Kojio K, Takahara A, Bhattacharya K, Urayama K. Probing the in-plane liquid-like behavior of liquid crystal elastomers. SCIENCE ADVANCES 2021; 7:eabe9495. [PMID: 34144981 PMCID: PMC8213220 DOI: 10.1126/sciadv.abe9495] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 05/05/2021] [Indexed: 06/12/2023]
Abstract
When isotropic solids are unequally stretched in two orthogonal directions, the true stress (force per actual cross-sectional area) in the larger strain direction is typically higher than that in the smaller one. We show that thiol-acrylate liquid crystal elastomers with polydomain texture exhibit an unusual tendency: The true stresses in the two directions are always identical and governed only by the area change in the loading plane, independently of the combination of imposed strains in the two directions. This feature proves a previously unidentified state of matter that can vary its shape freely with no extra mechanical energy like liquids when deformed in the plane. The theory and simulation that explain the unique behavior are also provided. The in-plane liquid-like behavior opens doors for manifold applications, including wrinkle-free membranes and adaptable materials.
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Affiliation(s)
- Haruki Tokumoto
- Department of Macromolecular Science and Engineering, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585, Japan
| | - Hao Zhou
- Department of Mechanical and Civil Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Asaka Takebe
- Department of Macromolecular Science and Engineering, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585, Japan
| | - Kazutaka Kamitani
- Institute for Materials Chemistry and Engineering, Kyushu University, Nishi-ku, Fukuoka 819-0395, Japan
| | - Ken Kojio
- Institute for Materials Chemistry and Engineering, Kyushu University, Nishi-ku, Fukuoka 819-0395, Japan
| | - Atsushi Takahara
- Institute for Materials Chemistry and Engineering, Kyushu University, Nishi-ku, Fukuoka 819-0395, Japan
| | - Kaushik Bhattacharya
- Department of Mechanical and Civil Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
| | - Kenji Urayama
- Department of Macromolecular Science and Engineering, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585, Japan.
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18
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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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19
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Ambulo CP, Ford MJ, Searles K, Majidi C, Ware TH. 4D-Printable Liquid Metal-Liquid Crystal Elastomer Composites. ACS APPLIED MATERIALS & INTERFACES 2021; 13:12805-12813. [PMID: 33356119 DOI: 10.1021/acsami.0c19051] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Soft actuators that undergo programmable shape change in response to a stimulus are enabling components of future soft robots and other soft machines. Strategies to power these actuators often require the incorporation of rigid, electrically conductive materials into the soft actuator, thus limiting the compliance and shape change of the material. In this study, we develop a 4D-printable composite composed of liquid crystal elastomer (LCE) matrix with dispersed droplets of eutectic gallium indium alloy (EGaIn). Using deformable EGaIn droplets in place of rigid conductive fillers preserves the compliance and shape-morphing properties of the LCE. The process enables 4D-printed LCE actuators capable of photothermal and electrothermal actuation. At low liquid metal (LM) concentrations (71 wt %), the composite actuator exhibits a photothermal response upon irradiation of near-IR light. Printed actuators with a twisted nematic configuration are capable of bending angles of 150° at 800 mW cm-2. At higher LM concentrations (88 wt %), the embedded LM droplets can form percolating networks that conduct electricity and enable electrical Joule heating of the LCE. Actuation strain ranging from 5 to 12% is controlled by the amount of electrical power that is delivered to the composite. We also introduce a method for multimaterial printing of monolithic structures where the LM filler loading is spatially varied. These multifunctional materials exhibit innate responsivity where the actuator behaves as an electrical switch and can report one of two states (on/off). These multiresponsive, 4D-printable composites enable multifunctional, mechanically active structures that can be powered with IR light or low DC voltages.
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Affiliation(s)
- Cedric P Ambulo
- Department of Bioengineering, The University of Texas at Dallas, Richardson, Texas 75080, United States
| | - Michael J Ford
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Kyle Searles
- Department of Bioengineering, The University of Texas at Dallas, Richardson, Texas 75080, United States
| | - Carmel Majidi
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Taylor H Ware
- Department of Bioengineering, The University of Texas at Dallas, Richardson, Texas 75080, United States
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas 77843, United States
- Department of Materials Science and Engineering, Texas A&M University, College Station, Texas 77843, United States
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20
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Okamoto S, Sakurai S, Urayama K. Effect of stretching angle on the stress plateau behavior of main-chain liquid crystal elastomers. SOFT MATTER 2021; 17:3128-3136. [PMID: 33599677 DOI: 10.1039/d0sm02244f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The equilibrium nonlinear stress-stretch relationships for a monodomain main-chain nematic elastomer (MNE) are investigated by varying the angle between the stretching and initial director axes (θ0). Angle θ0 has pronounced effects on the ultimate elongation as well as on the width of the low stress plateau regime (Λp) during director rotation, whereas θ0 has no appreciable effect on the plateau stress (σp). In the stretching normal to the initial director (θ0 = 90°), the plateau end exceeds 200% strain. At oblique angles of 90° > θ0≥ 35°, Λp decreases with decreasing θ0, whereas the definite plateau regime vanishes at θ0 < 24°. Wide-angle X-ray scattering and polarized optical microscopy measurements reveal that the director rotates uniformly in the biased direction for the MNE of θ0°≪ 90°, whereas directors rotating clockwise and counterclockwise are coexistent for θ0 = 90°. Over the entire plateau regime, the MNEs exhibit pure shear deformation characterized by a Poisson's ratio of zero in the direction of the rotation axis. The Λp for the corresponding polydomain NE (PNE) undergoing a transition to the monodomain alignment is smaller than that of the MNE of θ0 = 90°, while the σp values for both NEs are almost similar. The semi-soft elasticity concept satisfactorily explains the effects of θ0 on Λp, and the Λp value of the PNE, using a single anisotropy parameter which is evaluated from the degree of thermally induced deformation of MNEs.
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Affiliation(s)
- Suzuka Okamoto
- Department of Macromolecular Science and Engineering, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585, Japan.
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21
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Ambulo CP, Tasmim S, Wang S, Abdelrahman MK, Zimmern PE, Ware TH. Processing advances in liquid crystal elastomers provide a path to biomedical applications. JOURNAL OF APPLIED PHYSICS 2020; 128:140901. [PMID: 33060862 PMCID: PMC7546753 DOI: 10.1063/5.0021143] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 09/24/2020] [Indexed: 05/08/2023]
Abstract
Liquid crystal elastomers (LCEs) are a class of stimuli-responsive polymers that undergo reversible shape-change in response to environmental changes. The shape change of LCEs can be programmed during processing by orienting the liquid crystal phase prior to crosslinking. The suite of processing techniques that has been developed has resulted in a myriad of LCEs with different shape-changing behavior and mechanical properties. Aligning LCEs via mechanical straining yields large uniaxial actuators capable of a moderate force output. Magnetic fields are utilized to control the alignment within LCE microstructures. The generation of out-of-plane deformations such as bending, twisting, and coning is enabled by surface alignment techniques within thin films. 4D printing processes have emerged that enable the fabrication of centimeter-scale, 3D LCE structures with a complex alignment. The processing technique also determines, to a large extent, the potential applications of the LCE. For example, 4D printing enables the fabrication of LCE actuators capable of replicating the forces generated by human muscles. Employing surface alignment techniques, LCE films can be designed for use as coatings or as substrates for stretchable electronics. The growth of new processes and strategies opens and strengthens the path for LCEs to be applicable within biomedical device designs.
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Affiliation(s)
- Cedric P Ambulo
- Department of Bioengineering, The University of Texas at Dallas, Richardson, Texas 75080, USA
| | | | | | | | - Philippe E Zimmern
- Department of Urology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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22
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Effect of gold and graphene oxide nanoparticles on the thermo- and photo-actuation of monodomain liquid crystal elastomers. POLYMER 2020. [DOI: 10.1016/j.polymer.2020.122837] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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23
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Lee Y, Choi S, Kang BG, Ahn SK. Effect of Isomeric Amine Chain Extenders and Crosslink Density on the Properties of Liquid Crystal Elastomers. MATERIALS (BASEL, SWITZERLAND) 2020; 13:E3094. [PMID: 32664370 PMCID: PMC7412247 DOI: 10.3390/ma13143094] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 07/02/2020] [Accepted: 07/08/2020] [Indexed: 12/25/2022]
Abstract
Among the various types of shape changing materials, liquid crystal elastomers (LCEs) have received significant attention as they can undergo programmed and reversible shape transformations. The molecular engineering of LCEs is the key to manipulating their phase transition, mechanical properties, and actuation performance. In this work, LCEs containing three different types of butyl groups (n-, iso-, and sec-butyl) in the side chain were synthesized, and the effect of isomeric amine chain extenders on the thermal, mechanical, and actuation properties of the resulting LCEs was investigated. Because of the considerably low reactivity of the sec-butyl group toward the diacrylate in the LC monomer, only a densely crosslinked LCE was synthesized. Most interestingly, the mechanical properties, actuation temperature, and blocking stress of the LCEs comprising isobutyl groups were higher than those of the LCEs comprising n-butyl groups. This difference was attributed to the presence of branches in the LCEs with isobutyl groups, which resulted in a tighter molecular packing and reduced the free volume. Our results suggest a facile and effective method for synthesizing LCEs with tailored mechanical and actuation properties by the choice of chain extenders, which may advance the development of soft actuators for a variety of applications in aerospace, medicine, and optics.
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Affiliation(s)
- Yoojin Lee
- Department of Polymer Science and Engineering, Pusan National University, Busan 46241, Korea; (Y.L.); (S.C.)
| | - Subi Choi
- Department of Polymer Science and Engineering, Pusan National University, Busan 46241, Korea; (Y.L.); (S.C.)
| | - Beom-Goo Kang
- Department of Chemical Engineering, Soongsil University, Seoul 06978, Korea
| | - Suk-kyun Ahn
- Department of Polymer Science and Engineering, Pusan National University, Busan 46241, Korea; (Y.L.); (S.C.)
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24
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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: 39] [Impact Index Per Article: 9.8] [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.
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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.
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25
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Toward Programmed Complex Stress-Induced Mechanical Deformations of Liquid Crystal Elastomers. CRYSTALS 2020. [DOI: 10.3390/cryst10040315] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We prepare a liquid crystal elastomer (LCE) with a spatially patterned liquid crystal director field from an all-acrylate LCE. Mechanical deformations of this material lead to a complex and spatially varying deformation with localised body rotations, shears and extensions. Together, these dictate the evolved shape of the deformed film. Using polarising microscopy, we map the local rotation of the liquid crystal director in Eulerian and Lagrangian frames and use these to determine rules for programming complex, stress-induced mechanical shape deformations of LCEs. Moreover, by applying a recently developed empirical model for the mechanical behaviour of our LCE, we predict the non-uniform stress distributions in our material. These results show the promise of empirical approaches to modelling the anisotropic and nonlinear mechanical responses of LCEs which will be important as the community moves toward realising real-world, LCE-based devices.
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26
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Foelen Y, van der Heijden DAC, del Pozo M, Lub J, Bastiaansen CWM, Schenning APHJ. An Optical Steam Sterilization Sensor Based On a Dual-Responsive Supramolecular Cross-Linked Photonic Polymer. ACS APPLIED MATERIALS & INTERFACES 2020; 12:16896-16902. [PMID: 32223125 PMCID: PMC7146756 DOI: 10.1021/acsami.0c00711] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 03/12/2020] [Indexed: 05/06/2023]
Abstract
An optical time-temperature steam sensor is presented based on the loss of structural color in a supramolecularly cross-linked cholesteric liquid crystal photonic coating. A gradual decrease in the selective reflection band is observed upon exposure to temperatures above 105 °C related to the cholesteric to isotropic transition temperature. The linear polymers with carboxylic acid side chains provide physical cross-linking through hydrogen bonding that allows a time-temperature-dependent order loss through the dynamic equilibrium between supramolecular dimer and free monomer states. Steam is accelerating the color loss, and autoclave experiments show that the photonic supramolecular polymer is applicable as a steam sterilization sensor for medical applications.
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Affiliation(s)
- Yari Foelen
- Stimuli-responsive
Functional Materials and Devices, Department of Chemical Engineering
and Chemistry, Eindhoven University of Technology, P.O. Box 513, Eindhoven 5600 MB, The Netherlands
| | - Danielle A. C. van der Heijden
- Stimuli-responsive
Functional Materials and Devices, Department of Chemical Engineering
and Chemistry, Eindhoven University of Technology, P.O. Box 513, Eindhoven 5600 MB, The Netherlands
| | - Marc del Pozo
- Stimuli-responsive
Functional Materials and Devices, Department of Chemical Engineering
and Chemistry, Eindhoven University of Technology, P.O. Box 513, Eindhoven 5600 MB, The Netherlands
| | - Johan Lub
- Stimuli-responsive
Functional Materials and Devices, Department of Chemical Engineering
and Chemistry, Eindhoven University of Technology, P.O. Box 513, Eindhoven 5600 MB, The Netherlands
| | - Cees W. M. Bastiaansen
- Stimuli-responsive
Functional Materials and Devices, Department of Chemical Engineering
and Chemistry, Eindhoven University of Technology, P.O. Box 513, Eindhoven 5600 MB, The Netherlands
- School
of Engineering and Materials Science, Queen
Mary University of London, Mile End Road, London E1 4NS, U.K.
| | - Albert P. H. J. Schenning
- Stimuli-responsive
Functional Materials and Devices, Department of Chemical Engineering
and Chemistry, Eindhoven University of Technology, P.O. Box 513, Eindhoven 5600 MB, The Netherlands
- SCNU-TUE
Joint Laboratory of Device Integrated Responsive Materials (DIRM), South China Normal University, Guangzhou Higher Education Mega Center, Guangzhou 510006, China
- Institute
for Complex Molecular Systems, Eindhoven
University of Technology, Den Dolech 2, Eindhoven 5600 MB, The Netherlands
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27
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Davidson ZS, Shahsavan H, Aghakhani A, Guo Y, Hines L, Xia Y, Yang S, Sitti M. Monolithic shape-programmable dielectric liquid crystal elastomer actuators. SCIENCE ADVANCES 2019; 5:eaay0855. [PMID: 31803840 PMCID: PMC6874483 DOI: 10.1126/sciadv.aay0855] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2019] [Accepted: 09/23/2019] [Indexed: 05/18/2023]
Abstract
Soft robotics may enable many new technologies in which humans and robots physically interact, yet the necessary high-performance soft actuators still do not exist. The optimal soft actuators need to be fast and forceful and have programmable shape changes. Furthermore, they should be energy efficient for untethered applications and easy to fabricate. Here, we combine desirable characteristics from two distinct active material systems: fast and highly efficient actuation from dielectric elastomers and directed shape programmability from liquid crystal elastomers. Via a top-down photoalignment method, we program molecular alignment and localized giant elastic anisotropy into the liquid crystal elastomers. The linearly actuated liquid crystal elastomer monoliths achieve strain rates over 120% per second with an energy conversion efficiency of 20% while moving loads over 700 times the elastomer weight. The electric actuation mechanism offers unprecedented opportunities toward miniaturization with shape programmability, efficiency, and more degrees of freedom for applications in soft robotics and beyond.
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Affiliation(s)
- Zoey S. Davidson
- Physical Intelligence Department, Max Planck Institute for Intelligent Systems, Stuttgart, Germany
| | - Hamed Shahsavan
- Physical Intelligence Department, Max Planck Institute for Intelligent Systems, Stuttgart, Germany
| | - Amirreza Aghakhani
- Physical Intelligence Department, Max Planck Institute for Intelligent Systems, Stuttgart, Germany
| | - Yubing Guo
- Physical Intelligence Department, Max Planck Institute for Intelligent Systems, Stuttgart, Germany
| | - Lindsey Hines
- Physical Intelligence Department, Max Planck Institute for Intelligent Systems, Stuttgart, Germany
| | - Yu Xia
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA, USA
| | - Shu Yang
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA, USA
| | - Metin Sitti
- Physical Intelligence Department, Max Planck Institute for Intelligent Systems, Stuttgart, Germany
- School of Medicine and School of Engineering, Koç University, Istanbul, Turkey
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28
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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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29
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Donovan BR, Fowler HE, Matavulj VM, White TJ. Mechanotropic Elastomers. Angew Chem Int Ed Engl 2019; 58:13744-13748. [PMID: 31219675 DOI: 10.1002/anie.201905176] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 06/01/2019] [Indexed: 11/12/2022]
Abstract
Liquid crystal elastomers (LCEs) are anisotropic polymeric materials. When subjected to an applied stress, liquid crystalline (LC) mesogens within the elastomeric polymer network (re)orient to the loading direction. The (re)orientation during deformation results in nonlinear stress-strain dependence (referred to as soft elasticity). Here, we uniquely explore mechanotropic phase transitions in elastomers with appreciable mesogenic content and compare these responses to LCEs in the polydomain orientation. The isotropic (amorphous) elastomers undergo significant directional orientation upon loading, evident in strong birefringence and x-ray diffraction. Functionally, the mechanotropic displacement of the elastomers to load is also nonlinear. However, unlike the analogous polydomain LCE compositions examined here, the isotropic elastomers rapidly recover after deformation. The mechanotropic orientation of the mesogens in these materials increase the toughness of these thiol-ene photopolymers by nearly 1300 % relative to a chemically similar elastomer prepared from wholly isotropic precursors.
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Affiliation(s)
- Brian R Donovan
- University of Colorado Boulder, Department of Chemical and Biological Engineering, 596 UCB, Boulder, CO, 80309, USA
| | - Hayden E Fowler
- University of Colorado Boulder, Department of Chemical and Biological Engineering, 596 UCB, Boulder, CO, 80309, USA
| | - Valentina M Matavulj
- Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright Patterson Air Force Base, Dayton, OH, 45433-7750, USA
| | - Timothy J White
- University of Colorado Boulder, Department of Chemical and Biological Engineering, 596 UCB, Boulder, CO, 80309, USA.,Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright Patterson Air Force Base, Dayton, OH, 45433-7750, USA
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30
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Guo Y, Lee J, Son J, Ahn SK, Carrillo JMY, Sumpter BG. Decoding Liquid Crystal Oligomer Phase Transitions: Toward Molecularly Engineered Shape Changing Materials. Macromolecules 2019. [DOI: 10.1021/acs.macromol.9b01218] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Yuanhang Guo
- Department of Polymer Science and Engineering, Pusan National University, Busan 46241, Korea
| | - Jieun Lee
- Department of Polymer Science and Engineering, Pusan National University, Busan 46241, Korea
| | - Jinha Son
- Department of Polymer Science and Engineering, Pusan National University, Busan 46241, Korea
| | - Suk-kyun Ahn
- Department of Polymer Science and Engineering, Pusan National University, Busan 46241, Korea
| | - Jan-Michael Y. Carrillo
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
- Computational Sciences and Engineering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Bobby G. Sumpter
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
- Computational Sciences and Engineering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
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31
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Kotikian A, McMahan C, Davidson EC, Muhammad JM, Weeks RD, Daraio C, Lewis JA. Untethered soft robotic matter with passive control of shape morphing and propulsion. Sci Robot 2019; 4:4/33/eaax7044. [PMID: 33137783 DOI: 10.1126/scirobotics.aax7044] [Citation(s) in RCA: 148] [Impact Index Per Article: 29.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 07/30/2019] [Indexed: 01/07/2023]
Abstract
There is growing interest in creating untethered soft robotic matter that can repeatedly shape-morph and self-propel in response to external stimuli. Toward this goal, we printed soft robotic matter composed of liquid crystal elastomer (LCE) bilayers with orthogonal director alignment and different nematic-to-isotropic transition temperatures (T NI) to form active hinges that interconnect polymeric tiles. When heated above their respective actuation temperatures, the printed LCE hinges exhibit a large, reversible bending response. Their actuation response is programmed by varying their chemistry and printed architecture. Through an integrated design and additive manufacturing approach, we created passively controlled, untethered soft robotic matter that adopts task-specific configurations on demand, including a self-twisting origami polyhedron that exhibits three stable configurations and a "rollbot" that assembles into a pentagonal prism and self-rolls in programmed responses to thermal stimuli.
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Affiliation(s)
- Arda Kotikian
- John A. Paulson School of Engineering and Applied Sciences, Wyss Institute of Biologically Inspired Engineering, Cambridge, MA 02138, USA
| | - Connor McMahan
- Division of Engineering and Applied Science, California Institute of Technology, Pasadena, CA 91125, USA
| | - Emily C Davidson
- John A. Paulson School of Engineering and Applied Sciences, Wyss Institute of Biologically Inspired Engineering, Cambridge, MA 02138, USA
| | - Jalilah M Muhammad
- John A. Paulson School of Engineering and Applied Sciences, Wyss Institute of Biologically Inspired Engineering, Cambridge, MA 02138, USA
| | - Robert D Weeks
- John A. Paulson School of Engineering and Applied Sciences, Wyss Institute of Biologically Inspired Engineering, Cambridge, MA 02138, USA
| | - Chiara Daraio
- Division of Engineering and Applied Science, California Institute of Technology, Pasadena, CA 91125, USA.
| | - Jennifer A Lewis
- John A. Paulson School of Engineering and Applied Sciences, Wyss Institute of Biologically Inspired Engineering, Cambridge, MA 02138, USA.
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32
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Affiliation(s)
- Brian R. Donovan
- University of Colorado BoulderDepartment of Chemical and Biological Engineering, 596 UCB Boulder CO 80309 USA
| | - Hayden E. Fowler
- University of Colorado BoulderDepartment of Chemical and Biological Engineering, 596 UCB Boulder CO 80309 USA
| | - Valentina M. Matavulj
- Air Force Research LaboratoryMaterials and Manufacturing Directorate Wright Patterson Air Force Base Dayton OH 45433-7750 USA
| | - Timothy J. White
- University of Colorado BoulderDepartment of Chemical and Biological Engineering, 596 UCB Boulder CO 80309 USA
- Air Force Research LaboratoryMaterials and Manufacturing Directorate Wright Patterson Air Force Base Dayton OH 45433-7750 USA
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33
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Donovan BR, Matavulj VM, Ahn SK, Guin T, White TJ. All-Optical Control of Shape. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1805750. [PMID: 30417450 DOI: 10.1002/adma.201805750] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 10/12/2018] [Indexed: 06/09/2023]
Abstract
Photoresponsive liquid crystal elastomers (LCEs) are a unique class of anisotropic materials capable of undergoing large-scale, macroscopic deformations when exposed to light. Here, surface-aligned, azobenzene-functionalized LCEs are prepared via a radical-mediated, thiol-acrylate chain transfer reaction. A long-lived, macroscopic shape deformation is realized in an LCE composed with an o-fluorinated azobenzene (oF-azo) monomer. Under UV irradiation, the oF-azo LCE exhibits a persistent shape deformation for >72 h. By contrasting the photomechanical response of the oF-azo LCE to analogs prepared from classical and m-fluorinated azobenzene derivatives, the origin of the persistent deformation is clearly attributed to the underlying influence of positional functionalization on the kinetics of cis→trans isomerization. Informed by these studies and enabled by the salient features of light-induced deformations, oF-azo LCEs are demonstrated to undergo all-optical control of shape deformation and shape restoration.
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Affiliation(s)
- Brian R Donovan
- Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, Dayton, OH, 45433-7750, USA
- Azimuth Corporation, 4027 Colonel Glenn Highway, Beavercreek, OH, 45431, USA
| | - Valentina M Matavulj
- Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, Dayton, OH, 45433-7750, USA
- Azimuth Corporation, 4027 Colonel Glenn Highway, Beavercreek, OH, 45431, USA
| | - Suk-Kyun Ahn
- Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, Dayton, OH, 45433-7750, USA
- Azimuth Corporation, 4027 Colonel Glenn Highway, Beavercreek, OH, 45431, USA
| | - Tyler Guin
- Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, Dayton, OH, 45433-7750, USA
- Azimuth Corporation, 4027 Colonel Glenn Highway, Beavercreek, OH, 45431, USA
| | - Timothy J White
- Department of Chemical and Biological Engineering, University of Colorado Boulder, 3415 Colorado Ave., Boulder, CO, 80303, USA
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34
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Osicka J, Mrlik M, Ilcikova M, Hanulikova B, Urbanek P, Sedlacik M, Mosnacek J. Reversible Actuation Ability upon Light Stimulation of the Smart Systems with Controllably Grafted Graphene Oxide with Poly (Glycidyl Methacrylate) and PDMS Elastomer: Effect of Compatibility and Graphene Oxide Reduction on the Photo-Actuation Performance. Polymers (Basel) 2018; 10:E832. [PMID: 30960757 PMCID: PMC6403919 DOI: 10.3390/polym10080832] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 07/23/2018] [Accepted: 07/26/2018] [Indexed: 01/17/2023] Open
Abstract
This study is focused on the controllable reduction of the graphene oxide (GO) during the surface-initiated atom transfer radical polymerization technique of glycidyl methacrylate (GMA). The successful modification was confirmed using TGA-FTIR analysis and TEM microscopy observation of the polymer shell. The simultaneous reduction of the GO particles was confirmed indirectly via TGA and directly via Raman spectroscopy and electrical conductivity investigations. Enhanced compatibility of the GO-PGMA particles with a polydimethylsiloxane (PDMS) elastomeric matrix was proven using contact angle measurements. Prepared composites were further investigated through the dielectric spectroscopy to provide information about the polymer chain mobility through the activation energy. Dynamic mechanical properties investigation showed an excellent mechanical response on the dynamic stimulation at a broad temperature range. Thermal conductivity evaluation also confirmed the further photo-actuation capability properties at light stimulation of various intensities and proved that composite material consisting of GO-PGMA particles provide systems with a significantly enhanced capability in comparison with neat GO as well as neat PDMS matrix.
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Affiliation(s)
- Josef Osicka
- Centre of Polymer Systems, University Institute, Tomas Bata University in Zlín, Trida T. Bati 5678, 760 01 Zlín, Czech Republic.
| | - Miroslav Mrlik
- Centre of Polymer Systems, University Institute, Tomas Bata University in Zlín, Trida T. Bati 5678, 760 01 Zlín, Czech Republic.
| | - Marketa Ilcikova
- Polymer Institute, Slovak Academy of Sciences, Dúbravska cesta 9, 845 41 Bratislava, Slovakia.
| | - Barbora Hanulikova
- Centre of Polymer Systems, University Institute, Tomas Bata University in Zlín, Trida T. Bati 5678, 760 01 Zlín, Czech Republic.
| | - Pavel Urbanek
- Centre of Polymer Systems, University Institute, Tomas Bata University in Zlín, Trida T. Bati 5678, 760 01 Zlín, Czech Republic.
| | - Michal Sedlacik
- Centre of Polymer Systems, University Institute, Tomas Bata University in Zlín, Trida T. Bati 5678, 760 01 Zlín, Czech Republic.
| | - Jaroslav Mosnacek
- Polymer Institute, Slovak Academy of Sciences, Dúbravska cesta 9, 845 41 Bratislava, Slovakia.
- Centre for Advanced Materials Application, Slovak Academy of Sciences, Dúbravska cesta 9, 845 11 Bratislava, Slovakia.
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35
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Wen Z, McBride MK, Zhang X, Han X, Martinez AM, Shao R, Zhu C, Visvanathan R, Clark NA, Wang Y, Yang K, Bowman CN. Reconfigurable LC Elastomers: Using a Thermally Programmable Monodomain To Access Two-Way Free-Standing Multiple Shape Memory Polymers. Macromolecules 2018. [DOI: 10.1021/acs.macromol.8b01315] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Zhibin Wen
- Center for Degradable and Flame-Retardant Polymeric Materials (ERCEPM-MOE), National Engineering Laboratory of Eco-Friendly Polymeric Materials (Sichuan), State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610064, China
- Department of Chemical and Biological Engineering, Materials Science and Engineering Program, University of Colorado Boulder, Boulder, Colorado 80309, United States
- Department of Physics and Soft Materials Research Center, University of Colorado Boulder, Boulder, Colorado 80309-0390, United States
| | - Matthew K. McBride
- Department of Chemical and Biological Engineering, Materials Science and Engineering Program, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Xingpeng Zhang
- Department of Chemical and Biological Engineering, Materials Science and Engineering Program, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Xun Han
- Department of Chemical and Biological Engineering, Materials Science and Engineering Program, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Alina M. Martinez
- Department of Chemical and Biological Engineering, Materials Science and Engineering Program, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Renfan Shao
- Department of Physics and Soft Materials Research Center, University of Colorado Boulder, Boulder, Colorado 80309-0390, United States
| | - Chenhui Zhu
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Rayshan Visvanathan
- Department of Physics and Soft Materials Research Center, University of Colorado Boulder, Boulder, Colorado 80309-0390, United States
| | - Noel A. Clark
- Department of Physics and Soft Materials Research Center, University of Colorado Boulder, Boulder, Colorado 80309-0390, United States
| | - Yuzhong Wang
- Center for Degradable and Flame-Retardant Polymeric Materials (ERCEPM-MOE), National Engineering Laboratory of Eco-Friendly Polymeric Materials (Sichuan), State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610064, China
| | - Keke Yang
- Center for Degradable and Flame-Retardant Polymeric Materials (ERCEPM-MOE), National Engineering Laboratory of Eco-Friendly Polymeric Materials (Sichuan), State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610064, China
| | - Christopher N. Bowman
- Department of Chemical and Biological Engineering, Materials Science and Engineering Program, University of Colorado Boulder, Boulder, Colorado 80309, United States
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36
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Merkel DR, Traugutt NA, Visvanathan R, Yakacki CM, Frick CP. Thermomechanical properties of monodomain nematic main-chain liquid crystal elastomers. SOFT MATTER 2018; 14:6024-6036. [PMID: 29974115 DOI: 10.1039/c8sm01178h] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Two-stage thiol-acrylate Michael addition reactions have proven useful in programming main-chain liquid crystal elastomers (LCEs). However, the influence of excess acrylate concentration, which is critical to monodomain programming, has not previously been examined with respect to thermomechanical properties in these two-stage LCEs. Previous studies of thiol-acrylate LCEs have focused on polydomain LCEs and/or variation of thiol crosslinking monomers or linear thiol monomers. This study guides the design of monodomain LCE actuators using the two-stage methodology by varying the concentration of mesogenic acrylate monomers from 2 mol% to 45 mol% in stoichiometric excess of thiol. The findings demonstrate a technique to tailor the isotropic transition temperature by 44 °C using identical starting monomers. In contrast to expectations, low amounts of excess acrylate showed excellent fixity (90.4 ± 2.9%), while high amounts of excess acrylate did not hinder actuation strain (87.3 ± 2.3%). Tensile stress-strain properties were influenced by excess acrylate. Linear elastic behavior was observed parallel to the director with modulus increasing from 1.4 to 6.1 MPa. The soft elastic plateau was observed perpendicular to the director with initial modulus and threshold stresses increasing from 0.6 MPa to 2.6 MPa and 14 kPa to 208 kPa, respectively. Overall, this study examines the influence of excess acrylate on mechanical properties of LCE actuators.
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Affiliation(s)
- Daniel R Merkel
- University of Wyoming, Department of Mechanical Engineering, Laramie, WY, USA.
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37
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Kowalski BA, Mostajeran C, Godman NP, Warner M, White TJ. Curvature by design and on demand in liquid crystal elastomers. Phys Rev E 2018; 97:012504. [PMID: 29448377 DOI: 10.1103/physreve.97.012504] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Indexed: 12/27/2022]
Abstract
The shape of liquid crystalline elastomers (LCEs) with spatial variation in the director orientation can be transformed by exposure to a stimulus. Here, informed by previously reported analytical treatments, we prepare complex spiral patterns imprinted into LCEs and quantify the resulting shape transformation. Quantification of the stimuli-induced shapes reveals good agreement between predicted and experimentally observed curvatures. We conclude this communication by reporting a design strategy to allow LCE films to be anchored at their external boundaries onto rigid substrates without incurring internal, mechanical-mismatch stresses upon actuation, a critical advance to the realization of shape transformation of LCEs in practical device applications.
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Affiliation(s)
- B A Kowalski
- Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, USA.,Azimuth Corporation, Beavercreek, Ohio 45431, USA
| | - C Mostajeran
- Department of Engineering, University of Cambridge CB2 1PZ, United Kingdom
| | - N P Godman
- Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, USA
| | - M Warner
- Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, United Kingdom
| | - T J White
- Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, USA
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38
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Guin T, Settle MJ, Kowalski BA, Auguste AD, Beblo RV, Reich GW, White TJ. Layered liquid crystal elastomer actuators. Nat Commun 2018; 9:2531. [PMID: 29955053 PMCID: PMC6023890 DOI: 10.1038/s41467-018-04911-4] [Citation(s) in RCA: 110] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 05/29/2018] [Indexed: 11/25/2022] Open
Abstract
Liquid crystalline elastomers (LCEs) are soft, anisotropic materials that exhibit large shape transformations when subjected to various stimuli. Here we demonstrate a facile approach to enhance the out-of-plane work capacity of these materials by an order of magnitude, to nearly 20 J/kg. The enhancement in force output is enabled by the development of a room temperature polymerizable composition used both to prepare individual films, organized via directed self-assembly to retain arrays of topological defect profiles, as well as act as an adhesive to combine the LCE layers. The material actuator is shown to displace a load >2500× heavier than its own weight nearly 0.5 mm.
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Affiliation(s)
- Tyler Guin
- Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, OH, 45433, USA
- Azimuth Corporation, 4027 Colonel Glenn Hwy, Beavercreek, OH, 45431, USA
| | - Michael J Settle
- Air Force Research Laboratory, Aerospace Systems Directorate, Wright-Patterson Air Force Base, OH, 45433, USA
- University of Dayton Research Institute, 1700 S Patterson Blvd, Dayton, OH, 45469, USA
| | - Benjamin A Kowalski
- Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, OH, 45433, USA
- Azimuth Corporation, 4027 Colonel Glenn Hwy, Beavercreek, OH, 45431, USA
| | - Anesia D Auguste
- Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, OH, 45433, USA
| | - Richard V Beblo
- Air Force Research Laboratory, Aerospace Systems Directorate, Wright-Patterson Air Force Base, OH, 45433, USA
- University of Dayton Research Institute, 1700 S Patterson Blvd, Dayton, OH, 45469, USA
| | - Gregory W Reich
- Air Force Research Laboratory, Aerospace Systems Directorate, Wright-Patterson Air Force Base, OH, 45433, USA
| | - Timothy J White
- Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, OH, 45433, USA.
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39
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Qian X, Chen Q, Yang Y, Xu Y, Li Z, Wang Z, Wu Y, Wei Y, Ji Y. Untethered Recyclable Tubular Actuators with Versatile Locomotion for Soft Continuum Robots. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1801103. [PMID: 29806242 DOI: 10.1002/adma.201801103] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 03/30/2018] [Indexed: 05/23/2023]
Abstract
Stimuli-responsive materials offer a distinguished platform to build tether-free compact soft robots, which can combine sensing and actuation without a linked power supply. In the past, tubular soft robots have to be made by multiple components with various internal channels or complex cavities assembled together. Moreover, robust processing, complex locomotion, simple structure, and easy recyclability represent major challenges in this area. Here, it is shown that those challenges can be tackled by liquid crystalline elastomers with allyl sulfide functional groups. The light-controlled exchange reaction between allyl sulfide groups allows flexible processing of tubular soft robots/actuators, which does not need any assisting materials. Complex locomotion demonstrated here includes reversible simultaneous bending and elongation; reversible diameter expansion; and omnidirectional bending via remote infrared light control. Different modes of actuation can be programmed into the same tube without the routine assembly of multiple tubes as used in the past. In addition, the exchange reaction also makes it possible to use the same single tube repeatedly to perform different functions by erasing and reprogramming.
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Affiliation(s)
- Xiaojie Qian
- The Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology, Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Qiaomei Chen
- The Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology, Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Yang Yang
- The Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology, Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Yanshuang Xu
- The Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology, Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Zhen Li
- The Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology, Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Zhenhua Wang
- The Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology, Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Yahe Wu
- The Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology, Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Yen Wei
- The Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology, 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, 32023, Taiwan, China
| | - Yan Ji
- The Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology, Department of Chemistry, Tsinghua University, Beijing, 100084, China
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40
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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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