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Choi SH, Kim JH, Ahn J, Kim T, Jung Y, Won D, Bang J, Pyun KR, Jeong S, Kim H, Kim YG, Ko SH. Phase patterning of liquid crystal elastomers by laser-induced dynamic crosslinking. NATURE MATERIALS 2024; 23:834-843. [PMID: 38532072 DOI: 10.1038/s41563-024-01845-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 02/21/2024] [Indexed: 03/28/2024]
Abstract
Liquid crystal elastomers hold promise in various fields due to their reversible transition of mechanical and optical properties across distinct phases. However, the lack of local phase patterning techniques and irreversible phase programming has hindered their broad implementation. Here we introduce laser-induced dynamic crosslinking, which leverages the precision and control offered by laser technology to achieve high-resolution multilevel patterning and transmittance modulation. Incorporation of allyl sulfide groups enables adaptive liquid crystal elastomers that can be reconfigured into desired phases or complex patterns. Laser-induced dynamic crosslinking is compatible with existing processing methods and allows the generation of thermo- and strain-responsive patterns that include isotropic, polydomain and monodomain phases within a single liquid crystal elastomer film. We show temporary information encryption at body temperature, expanding the functionality of liquid crystal elastomer devices in wearable applications.
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Affiliation(s)
- Seok Hwan Choi
- Department of Mechanical Engineering, Seoul National University, Seoul, Republic of Korea
| | - Ju Hee Kim
- Department of Chemical and Biological Engineering and Institute of Chemical Processes, Seoul National University, Seoul, Republic of Korea
| | - Jiyong Ahn
- Department of Mechanical Engineering, Seoul National University, Seoul, Republic of Korea
| | - Taegyeom Kim
- Department of Mechanical Engineering, Seoul National University, Seoul, Republic of Korea
| | - Yeongju Jung
- Department of Mechanical Engineering, Seoul National University, Seoul, Republic of Korea
| | - Daeyeon Won
- Department of Mechanical Engineering, Seoul National University, Seoul, Republic of Korea
| | - Junhyuk Bang
- Department of Mechanical Engineering, Seoul National University, Seoul, Republic of Korea
| | - Kyung Rok Pyun
- Department of Mechanical Engineering, Seoul National University, Seoul, Republic of Korea
| | - Seongmin Jeong
- Department of Mechanical Engineering, Seoul National University, Seoul, Republic of Korea
| | - Hyunsu Kim
- Department of Mechanical Engineering, Seoul National University, Seoul, Republic of Korea
| | - Young Gyu Kim
- Department of Chemical and Biological Engineering and Institute of Chemical Processes, Seoul National University, Seoul, Republic of Korea
| | - Seung Hwan Ko
- Department of Mechanical Engineering, Seoul National University, Seoul, Republic of Korea.
- Institute of Engineering Research / Institute of Advanced Machinery and Design (SNU-IAMD), Seoul National University, Seoul, Republic of Korea.
- Interdisciplinary Program in Bioengineering, Seoul National University, Seoul, Korea.
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2
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Jiang Z, Tran BH, Jolfaei MA, Abbasi BBA, Spinks GM. Crack-Resistant and Tissue-Like Artificial Muscles with Low Temperature Activation and High Power Density. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024:e2402278. [PMID: 38657958 DOI: 10.1002/adma.202402278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Revised: 04/11/2024] [Indexed: 04/26/2024]
Abstract
Constructing soft robotics with safe human-machine interactions requires low-modulus, high-power-density artificial muscles that are sensitive to gentle stimuli. In addition, the ability to resist crack propagation during long-term actuation cycles is essential for a long service life. Herein, a material design is proposed to combine all these desirable attributes in a single artificial muscle platform. The design involves the molecular engineering of a liquid crystalline network with crystallizable segments and an ethylene glycol flexible spacer. A high degree of crystallinity can be afforded by utilizing aza-Michael chemistry to produce a low covalent crosslinking density, resulting in crack-insensitivity with a high fracture energy of 33 720 J m-2 and a high fatigue threshold of 2250 J m-2. Such crack-resistant artificial muscle with tissue-matched modulus of 0.7 MPa can generate a high power density of 450 W kg-1 at a low temperature of 40 °C. Notably, because of the presence of crystalline domains in the actuated state, no crack propagation is observed after 500 heating-cooling actuation cycles under a static load of 220 kPa. This study points to a pathway for the creation of artificial muscles merging seemingly disparate, but desirable properties, broadening their application potential in smart devices.
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Affiliation(s)
- Zhen Jiang
- School of Mechanical, Materials, Mechatronic and Biomedical Engineering, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - Bach H Tran
- School of Mechanical, Materials, Mechatronic and Biomedical Engineering, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - Maryam Adavoudi Jolfaei
- School of Mechanical, Materials, Mechatronic and Biomedical Engineering, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - Burhan Bin Asghar Abbasi
- School of Mechanical, Materials, Mechatronic and Biomedical Engineering, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - Geoffrey M Spinks
- School of Mechanical, Materials, Mechatronic and Biomedical Engineering, University of Wollongong, Wollongong, NSW, 2522, Australia
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3
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Herman JA, Hoang JD, White TJ. Elastocaloric Response of Isotropic Liquid Crystalline Elastomers. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024:e2400786. [PMID: 38506590 DOI: 10.1002/smll.202400786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 02/28/2024] [Indexed: 03/21/2024]
Abstract
Liquid crystalline elastomers (LCEs) are soft materials that associate order and deformation. Upon deformation, mechanically induced changes order affect entropy and can produce a caloric output (elastocaloric). Elastocaloric effects in materials continue to be considered for functional use as solid state refrigerants. Prior elastocaloric investigations of LCEs and related materials have measured ≈2 °C temperature changes upon deformation (100% strain). Here, the elastocaloric response of LCEs is explored that are prepared with a subambient nematic to isotropic transition temperature. These materials are referred as "isotropic" liquid crystalline elastomers. The LCEs are prepared by a two-step thiol-Michael/thiol-ene reaction. This polymer network chemistry enhances elastic recovery and reduces hysteresis compared to acrylate-based chemistries. The LCEs exhibit appreciable elastocaloric temperature changes upon deformation and recovery (> ± 3 °C, total ΔT of 6 °C) to deformation driven by minimal force (<< 1 MPa). Notably, the strong association of deformation and order and the resulting temperature change attained at low force achieves a responsivity of 14 °C MPa-1 which is seven times greater than natural rubber.
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Affiliation(s)
- Jeremy A Herman
- Department of Chemical and Biological Engineering, University of Colorado, Jennie Smoly Caruthers Biotechnology Building, 3415 Colorado Ave, Boulder, CO, 80303, USA
| | - Jonathan D Hoang
- Materials Science and Engineering Program, University of Colorado, Jennie Smoly Caruthers Biotechnology Building, 3415 Colorado Ave, Boulder, CO, 80303, USA
| | - Timothy J White
- Department of Chemical and Biological Engineering, University of Colorado, Jennie Smoly Caruthers Biotechnology Building, 3415 Colorado Ave, Boulder, CO, 80303, USA
- Materials Science and Engineering Program, University of Colorado, Jennie Smoly Caruthers Biotechnology Building, 3415 Colorado Ave, Boulder, CO, 80303, USA
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4
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Jin B, Zhu Z, Wong TW, Chen G. Network Topology Optimization for Alignment Programming of a Dynamic Liquid Crystalline Organo-Gel. ACS Macro Lett 2023; 12:1486-1490. [PMID: 37874195 DOI: 10.1021/acsmacrolett.3c00512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Liquid crystalline elastomers (LCEs) exhibit muscle-like actuation upon an external stimulus. To control this, various alignment programming strategies have been developed over the past decades. Among them, force-directed solvent evaporation, namely, that the alignment depends on the applied external force during solvent evaporation, is appreciated for its universality in material design and versatility in attainable actuations. Here, we investigate the influence of network topology on the alignment programming of a liquid crystalline (LC) organo-gel via varying feeding ratios of the monomers. As a result, distinct self-supporting actuations can be repeatedly introduced into a topology-optimized LC organo-gel. Beyond this, the bond exchange reaction of the embedded ester groups can be activated upon heating, which enables alignment manipulation based on dynamic network reconfiguration after drying. The availability of inviting two distinct programming strategies into one LCE network allows us to regulate the LCE alignment at both the gel and dried states, offering ample room to diversify actuation manners. Our design principle shall be adopted by other dynamic LCE systems owing to its maneuverability.
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Affiliation(s)
- Binjie Jin
- State Key Laboratory of Chemical Engineering, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, Zhejiang, China
| | - Zhan Zhu
- State Key Laboratory of Chemical Engineering, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, Zhejiang, China
| | - Tuck-Whye Wong
- Membrane Technology Research Centre, School of Chemical and Energy Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Malaysia
| | - Guancong Chen
- College of Material, Chemistry and Chemical Engineering, Key Laboratory of Organosilicon Chemistry and Material Technology, Ministry of Education, Hangzhou Normal University, Hangzhou 311121, Zhejiang, China
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5
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Chen G, Feng H, Zhou X, Gao F, Zhou K, Huang Y, Jin B, Xie T, Zhao Q. Programming actuation onset of a liquid crystalline elastomer via isomerization of network topology. Nat Commun 2023; 14:6822. [PMID: 37884494 PMCID: PMC10603074 DOI: 10.1038/s41467-023-42594-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 10/16/2023] [Indexed: 10/28/2023] Open
Abstract
Tuning actuation temperatures of liquid crystalline elastomers (LCEs) achieves control of their actuation onsets, which is generally accomplished in the synthesis step and cannot be altered afterward. Multiple actuation onsets in one LCE can be encoded if the post-synthesis regulation of actuation temperature can be spatiotemporally achieved. This would allow realizing a logical time-evolution of actuation, desired for future soft robots. Nevertheless, this task is challenging given the additional need to ensure mesogen alignment required for actuation. We achieved this goal with a topology isomerizable network (TIN) of LCE containing aromatic and aliphatic esters in the mesogenic and amorphous phases, respectively. These two ester bonds can be distinctly activated for transesterification. The homolytic bond exchange between aliphatic esters allows mechanically induced mesogen alignment without affecting the mesogenic phase. Most importantly, the heterolytic exchange between aromatic and aliphatic esters changes the actuation temperature under different conditions. Spatial control of the two mechanisms via a photo-latent catalyst unleashes the freedom in regulating actuation temperature distribution, yielding unusual controllability in actuation geometries and logical sequence. Our principle is generally applicable to common LCEs containing both aromatic and aliphatic esters.
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Affiliation(s)
- Guancong Chen
- State Key Laboratory of Chemical Engineering, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, 310027, Zhejiang, China
- College of Material, Chemistry and Chemical Engineering, Key Laboratory of Organosilicon Chemistry and Material Technology, Ministry of Education, Hangzhou Normal University, Hangzhou, 311121, Zhejiang, China
| | - Haijun Feng
- State Key Laboratory of Chemical Engineering, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, 310027, Zhejiang, China
| | - Xiaorui Zhou
- State Key Laboratory of Chemical Engineering, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, 310027, Zhejiang, China
| | - Feng Gao
- National Engineering Laboratory for Textile Fiber Materials & Processing Technology, Zhejiang Sci-Tech University, Hangzhou, 310018, Zhejiang, China
| | - Kai Zhou
- State Key Laboratory of Chemical Engineering, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, 310027, Zhejiang, China
| | - Youju Huang
- College of Material, Chemistry and Chemical Engineering, Key Laboratory of Organosilicon Chemistry and Material Technology, Ministry of Education, Hangzhou Normal University, Hangzhou, 311121, Zhejiang, China
| | - Binjie Jin
- State Key Laboratory of Chemical Engineering, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, 310027, Zhejiang, China.
| | - Tao Xie
- State Key Laboratory of Chemical Engineering, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, 310027, Zhejiang, China
| | - Qian Zhao
- State Key Laboratory of Chemical Engineering, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, 310027, Zhejiang, China.
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6
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Chai J, Chen J, Kang Z, Lu L, Tang CH, Fan J. Temperature-adaptive rooftop covering with synergetic modulation of solar and thermal radiation for maximal energy saving. iScience 2023; 26:107388. [PMID: 37554460 PMCID: PMC10404751 DOI: 10.1016/j.isci.2023.107388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 06/21/2023] [Accepted: 07/11/2023] [Indexed: 08/10/2023] Open
Abstract
The energy consumption for maintaining desired indoor temperature accounts for 20% of primary energy use worldwide. Passive rooftop modulation of solar/thermal radiation without external energy input has a great potential in building energy saving. However, existing passive rooftop modulation techniques failed to simultaneously modulate solar/thermal radiation in response to rooftop surface temperature which is closely related to the building thermal loads, leading to limited or even counter-productive overall energy saving. Here, we report the development of a surface temperature-adaptive rooftop covering with synergetic solar and thermal modulations. The covering, made of a scalable metalized polyethylene film, demonstrated excellent solar absorptance modulation (72.5%) and thermal emissivity modulation (79%) in response to its temperature change from 22°C (indoor heating setpoint) to 25°C (indoor cooling setpoint), and vice versa. Building energy simulations demonstrate that the proposed rooftop covering can achieve all-season energy savings across all climate regions.
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Affiliation(s)
- Jiale Chai
- School of Fashion and Textiles, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China
| | - Jianheng Chen
- Renewable Energy Research Group (RERG), Department of Building Environment and Energy Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China
| | - Zhanxiao Kang
- School of Fashion and Textiles, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China
| | - Lin Lu
- Renewable Energy Research Group (RERG), Department of Building Environment and Energy Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China
| | - Chi-Hung Tang
- The Surface Engineering Unit of the Additive Manufacturing Stream, Industrial Centre, the Hong Kong Polytechnic University, Kowloon, Hong Kong, China
| | - Jintu Fan
- School of Fashion and Textiles, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China
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7
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Zhang X, Liao W, Wang Y, Yang Z. Thermal-Responsive Liquid Crystal Elastomer Foam-based Compressible and Omnidirectional Gripper. Chem Asian J 2023; 18:e202300340. [PMID: 37325932 DOI: 10.1002/asia.202300340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 06/13/2023] [Accepted: 06/15/2023] [Indexed: 06/17/2023]
Abstract
Liquid crystal elastomers (LCEs) are considered to be a promising material for the fabrication of soft grippers because of their large and reversible deformations, an LCE gripper with suitable compressibility and omnidirectionality has not yet been developed. To overcome these obstacles, this study utilizes salt template method to fabricate a rod-like LCE foam as gripper. The thickness of the compressible foam can be reduced by up to 77%, temporarily maintaining the deformation and enabling the gripper to pass through slits. The foam was aligned along the long axis and the length of the foam exhibits reversible thermal responsiveness and contract up to 57% along its alignment. Additionally, when the foam approaches a heat source, the generated temperature gradient results in a contraction gradient owing to the low thermal conductivity of the LCE foam. This in turn causes the foam to reversibly bend with a bending angle up to 93° and follow the movement of a heat source omnidirectionally. The developed gripper successfully grasps, moves, and releases hot objects in a cold and safe place, demonstrating its potential for emergency disposal. Thus, LCE foams can be considered suitable materials for novel gripper design and construction.
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Affiliation(s)
- Xinyuhang Zhang
- Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Department of Chemistry, Tsinghua University, 100084, Beijing, P. R. China
| | - Wei Liao
- Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Department of Chemistry, Tsinghua University, 100084, Beijing, P. R. China
| | - Yunpeng Wang
- Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Department of Chemistry, Tsinghua University, 100084, Beijing, P. R. China
| | - Zhongqiang Yang
- Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Department of Chemistry, Tsinghua University, 100084, Beijing, P. R. China
- Laboratory of Flexible Electronics Technology, Tsinghua University, 100084, Beijing, P. R. China
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8
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Zhan Y, Broer DJ, Li J, Xue J, Liu D. A cold-responsive liquid crystal elastomer provides visual signals for monitoring a critical temperature decrease. MATERIALS HORIZONS 2023. [PMID: 37098874 DOI: 10.1039/d3mh00271c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Critical temperature indicators have been extensively utilized in various fields, ranging from healthcare to food safety. However, the majority of the temperature indicators are designed for upper critical temperature monitoring, indicating when the temperature rises and exceeds a predefined limit, whereas stringently demanded low critical temperature indicators are scarcely developed. Herein, we develop a new material and system that monitor temperature decrease, e.g., from ambient temperature to the freezing point, or even to an ultra-low temperature of -20 °C. For this purpose, we create a dynamic membrane which can open and close during temperature cycles from high temperature to low temperature. This membrane consists of a gold-liquid crystal elastomer (Au-LCE) bilayer structure. Unlike the commonly used thermo-responsive LCEs which actuate upon temperature rise, our LCE is cold-responsive. This means that geometric deformations occur when the environmental temperature decreases. Specifically, upon temperature decrease the LCE creates stresses at the gold interface by uniaxial deformation due to expansion along the molecular director and shrinkage perpendicular to it. At a critical stress, optimized to occur at the desired temperature, the brittle Au top layer fractures, which allows contact between the LCE and material on top of the gold layer. Material transport via cracks enables the onset of the visible signal for instance caused by a pH indicator substance. We apply the dynamic Au-LCE membrane for cold-chain applications, indicating the loss of the effectiveness of perishable goods. We anticipate that our newly developed low critical temperature/time indicator will be shortly implemented in supply chains to minimize food and medical product waste.
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Affiliation(s)
- Yuanyuan Zhan
- Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Groene Loper 3, 5612 AE Eindhoven, The Netherlands.
- Institute for Complex Molecular Systems (ICMS), Eindhoven University of Technology, Groene Loper 3, 5612 AE Eindhoven, The Netherlands
| | - Dirk J Broer
- Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Groene Loper 3, 5612 AE Eindhoven, The Netherlands.
- Institute for Complex Molecular Systems (ICMS), Eindhoven University of Technology, Groene Loper 3, 5612 AE Eindhoven, The Netherlands
| | - Junyu Li
- Molecular Materials and Nanosystems, Eindhoven University of Technology, Groene Loper 3, 5612 AE Eindhoven, The Netherlands
| | - Jiuzhi Xue
- Smart Liquid Crystal Technologies Co. Ltd, Jiangsu Industrial Technology Research Institute (JITRI), 280 Huangpujiang Road, Chuangshu, 215556, China
| | - Danqing Liu
- Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Groene Loper 3, 5612 AE Eindhoven, The Netherlands.
- Institute for Complex Molecular Systems (ICMS), Eindhoven University of Technology, Groene Loper 3, 5612 AE Eindhoven, The Netherlands
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9
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Najiya N, Popov N, Jampani VSR, Lagerwall JPF. Continuous Flow Microfluidic Production of Arbitrarily Long Tubular Liquid Crystal Elastomer Peristaltic Pump Actuators. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2204693. [PMID: 36494179 DOI: 10.1002/smll.202204693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Revised: 11/14/2022] [Indexed: 06/17/2023]
Abstract
While liquid crystal elastomers (LCEs) are ideal materials for soft-robotic actuators, filling the role of muscle and shape-defining material simultaneously, it is non-trivial to give them ground state shapes beyond simple sheets or fibers. Here tubular LCE actuators scalable to arbitrary length are produced using a continuous three-phase coaxial flow microfluidic process. By pumping an oligomeric precursor solution between inner and outer aqueous phases in a cylindrically symmetric nested capillary set-up, and by reducing the interfacial tension to negligible values using surfactants adapted to each phase, the tubular liquid flow is stabilized over distances more than 200 times the diameter or 2000 times the thickness. In situ photocrosslinking of the middle phase turns it into an LCE network that is flow-aligned by the shear gradient over the phase. The reversible actuation of the tubes upon heating yields a reduction of the interior space, pumping out enclosed fluid, and the relaxation upon cooling leads to the fluid being sucked back in. By moving a local heat source along the tube, it acts as a peristaltic pump. It is proposed that the tubes could, pending functionalization for light-triggered actuation, function as active synthetic vasculature in biological contexts.
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Affiliation(s)
- Najiya Najiya
- Department of Physics and Materials Science, University of Luxembourg, 162a avenue de la faiencerie, Luxembourg city, 1511, Luxembourg
| | - Nikolay Popov
- Department of Physics and Materials Science, University of Luxembourg, 162a avenue de la faiencerie, Luxembourg city, 1511, Luxembourg
| | - Venkata Subba Rao Jampani
- Department of Physics and Materials Science, University of Luxembourg, 162a avenue de la faiencerie, Luxembourg city, 1511, Luxembourg
- Department of Condensed Matter Physics, Jozef Stefan Institute, Jamova 39, Ljubljana, 1000, Slovenia
| | - Jan P F Lagerwall
- Department of Physics and Materials Science, University of Luxembourg, 162a avenue de la faiencerie, Luxembourg city, 1511, Luxembourg
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10
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Bauman GE, Hoang JD, Toney MF, White TJ. Degree of Orientation in Liquid Crystalline Elastomers Defines the Magnitude and Rate of Actuation. ACS Macro Lett 2023; 12:248-254. [PMID: 36715430 DOI: 10.1021/acsmacrolett.2c00754] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The anisotropy of liquid crystalline elastomers (LCEs) is derived from the interaction-facilitated orientation of the molecular constituents. Here, we correlate the thermomechanical response of a series of LCEs subjected to mechanical alignment to measurements of the Hermans orientation parameter. The LCEs were systematically prepared with varying concentrations of liquid crystalline mesogens, which affects the relative degree of achievable order. These compositions were subject to varying degrees of mechanical alignment to prepare LCEs with orientations that span a wide range of orientation parameters. The stimuli-response of the LCEs indicates that the liquid crystalline content defines the temperature of actuation, whereas the orientation parameter of the LCE is intricately correlated to both the total actuation strain of the LCE as well as the rate of thermomechanical response.
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Affiliation(s)
- Grant E Bauman
- Department of Chemical and Biological Engineering, University of Colorado Boulder, 596 UCB, Boulder, Colorado 80309, United States
| | - Jonathan D Hoang
- Materials Science and Engineering Program, University of Colorado Boulder, 613 UCB, Boulder, Colorado 80303, United States
| | - Michael F Toney
- Department of Chemical and Biological Engineering, University of Colorado Boulder, 596 UCB, Boulder, Colorado 80309, United States.,Materials Science and Engineering Program, University of Colorado Boulder, 613 UCB, Boulder, Colorado 80303, United States.,Renewable and Sustainable Energy Institute, University of Colorado Boulder, 027 UCB, Boulder, Colorado 80309, United States
| | - Timothy J White
- Department of Chemical and Biological Engineering, University of Colorado Boulder, 596 UCB, Boulder, Colorado 80309, United States.,Materials Science and Engineering Program, University of Colorado Boulder, 613 UCB, Boulder, Colorado 80303, United States
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11
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Liao W, Yang Z. 3D printing programmable liquid crystal elastomer soft pneumatic actuators. MATERIALS HORIZONS 2023; 10:576-584. [PMID: 36468657 DOI: 10.1039/d2mh01001a] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Soft pneumatic actuators (SPAs) rely on anisotropic mechanical properties to generate specific motions after inflation. To achieve mechanical anisotropy, additional stiff materials or heterogeneous structures are typically introduced in isotropic base materials. However, the inherent limitations of these strategies may lead to potential interfacial problems or inefficient material usage. Herein, we develop a new strategy for fabricating SPAs based on an aligned liquid crystal elastomer (LCE) by a modified 3D printing technology. A rotating substrate enables the one-step fabrication of tubular LCE-SPAs with designed alignments in three dimensions. The alignment can be precisely programmed through printing, resulting in intrinsic mechanical anisotropy of the LCE. With a specially designed alignment, LCE-SPAs can achieve basic motions-contraction, elongation, bending, and twisting-and accomplish diverse tasks, e.g., grabbing objects and mixing water. This study provides a new perspective for the design and fabrication of SPAs.
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Affiliation(s)
- Wei Liao
- Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Department of Chemistry, Tsinghua University, Beijing, China.
| | - Zhongqiang Yang
- Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Department of Chemistry, Tsinghua University, Beijing, China.
- Laboratory of Flexible Electronics Technology, Tsinghua University, Beijing, China
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12
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Jiang Y, Dong X, Zhu S, Dai S, Bai H, Li Q, Li L, Yuan N, Ding J. Skin-friendly and antibacterial monodomain liquid crystal elastomer actuator. Colloids Surf B Biointerfaces 2023; 222:113110. [PMID: 36586236 DOI: 10.1016/j.colsurfb.2022.113110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 12/13/2022] [Accepted: 12/18/2022] [Indexed: 12/24/2022]
Abstract
Monodomain liquid crystal elastomers (mLCEs) are flexible and biocompatible smart materials that show unique behaviors of soft elasticity, anisotropy, and reversible shape changes above the nematic-isotropic transition temperature. Therefore, it has great potential for application in wearable devices and biologically. However, most of the reported mLCEs have nematic-isotropic transition temperature (TNI) higher than 60 °C; and above this TNI, the tensile strength of the mLCEs decreases by orders of magnitude. These issues have received little attention, limiting their application in humans. Herein, the TNI of mLCEs was reduced from 78.4 °C to 23.5 °C by substituting part of the rigid LC mesogens with a flexible backbone. The physical entanglement of hydrogen bonds between molecular chains alleviated the molecular chain slip caused by the long flexible backbone. The tensile strength remained constant during the phase transformation. Furthermore, dynamic disulfide bonds were used to modify the LC polymer network, imparting it with excellent antimicrobial, programmable, and self-healing properties. To realize its application in the closure of skin wounds, a porous PHG-mLCE/hydrogel patch that was breathable and waterproof was designed to increase skin adhesion (262 N/m).
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Affiliation(s)
- Yaoyao Jiang
- Jiangsu Collaborative Innovation Centre for Photovoltaic Science and Engineering, Changzhou University, Changzhou 213164, PR China
| | - Xu Dong
- School of Mechanical Engineering, Yangzhou University, Yangzhou 225009, PR China
| | - Shijie Zhu
- Jiangsu Collaborative Innovation Centre for Photovoltaic Science and Engineering, Changzhou University, Changzhou 213164, PR China
| | - Shengping Dai
- School of Chemistry and Chemical Engineering, Jinggangshan University, Ji'an 343009, PR China
| | - Hongyu Bai
- Jiangsu Collaborative Innovation Centre for Photovoltaic Science and Engineering, Changzhou University, Changzhou 213164, PR China
| | - Qingyue Li
- Jiangsu Collaborative Innovation Centre for Photovoltaic Science and Engineering, Changzhou University, Changzhou 213164, PR China
| | - Lvzhou Li
- School of Mechanical Engineering, Yangzhou University, Yangzhou 225009, PR China.
| | - Ningyi Yuan
- Jiangsu Collaborative Innovation Centre for Photovoltaic Science and Engineering, Changzhou University, Changzhou 213164, PR China.
| | - Jianning Ding
- Jiangsu Collaborative Innovation Centre for Photovoltaic Science and Engineering, Changzhou University, Changzhou 213164, PR China; School of Mechanical Engineering, Yangzhou University, Yangzhou 225009, PR China.
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13
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Zhang X, Yao L, Yan H, Zhang Y, Han D, He Y, Li C, Zhang J. Optical wavelength selective actuation of dye doped liquid crystalline elastomers by quasi-daylight. SOFT MATTER 2022; 18:9181-9196. [PMID: 36437786 DOI: 10.1039/d2sm01256a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
We explore obtaining different photo responses of liquid crystalline elastomer (LCE) materials through modulating the optical wavelengths in order to promote the development of precise photocontrol on LCE actuators, and thus study the effect of light-absorbing dyes with different absorption bands on the selective actuation of LCE materials. The dye-doped LCEs were prepared by incorporating special visible absorber dyes into thiol-acrylate main chain LCE (MC-LCE) matrices. The dyes showed photo actuation performance to LCEs due to the photothermal effects. But, every dye-doped LCE could be effectively actuated by light irradiation whose wavelength was inside its absorption band, but could not be effectively actuated by the light whose wavelength was beyond its absorption band. Wavelength selective actuation effects, no matter actuating deformation or actuating force, could be remarkably demonstrated by these dye-doped LCEs through filtering the same quasi-daylight source to be different wavelength bands. Our work opens up a significant way for the precise and convenient photo actuation of LCE actuators, while expanding the utilization potential of quasi-daylight, and further natural sunlight.
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Affiliation(s)
- Xinyu Zhang
- Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education of the People's Republic of China, Heilongjiang University, Harbin 150080, P. R. China.
| | - Liru Yao
- Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education of the People's Republic of China, Heilongjiang University, Harbin 150080, P. R. China.
| | - Huixuan Yan
- Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education of the People's Republic of China, Heilongjiang University, Harbin 150080, P. R. China.
| | - Yuhe Zhang
- Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education of the People's Republic of China, Heilongjiang University, Harbin 150080, P. R. China.
| | - Dongxu Han
- Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education of the People's Republic of China, Heilongjiang University, Harbin 150080, P. R. China.
| | - Yifan He
- Institute of Regulatory Science, Beijing Technology and Business University, Beijing 100048, P. R. China
| | - Chensha Li
- Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education of the People's Republic of China, Heilongjiang University, Harbin 150080, P. R. China.
| | - Jianqi Zhang
- Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190, P. R. China.
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14
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Kim H, Li J, Hsieh YSY, Cho M, Ahn SH, Li C. Photo-Programmed Deformations in Rigid Liquid Crystalline Polymers Triggered by Body Temperature. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2203772. [PMID: 36169084 DOI: 10.1002/smll.202203772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 09/13/2022] [Indexed: 06/16/2023]
Abstract
Deformations triggered by body heat are desirable in the context of shape-morphing applications because, under the majority of circumstances, the human body maintains a higher temperature than that of its surroundings. However, at present, this bioenergy-triggered action is primarily limited to soft polymeric networks. Thus, herein, the programming of body temperature-triggered deformations into rigid azobenzene-containing liquid crystalline polymers (azo-LCPs) with a glass-transition temperature of 100 °C is demonstrated. To achieve this, a mechano-assisted photo-programming strategy is used to create a metastable state with room-temperature stable residual stress, which is induced by the isomerization of azobenzene. The programmed rigid azo-LCP can undergo large-amplitude body temperature-triggered shape changes within minutes and can be regenerated without any performance degradation. By changing the programming photomasks and irradiation conditions employed, various 2D to 3D shape-morphing architectures, including folded clips, inch-worm structures, spiral structures, and snap-through motions are achieved. When programmed with polarized light, the proposed strategy results in domain-selective activation, generating designed characteristics in multi-domain azo-LCPs. The reported strategy is therefore expected to broaden the applications of azo-LCPs in the fields of biomedical and flexible microelectronic devices.
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Affiliation(s)
- Hyunsu Kim
- Department of Mechanical and Aerospace Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 151-742, Republic of Korea
| | - Jing Li
- Development Center of Plant Germplasm Resources, College of Life Sciences, Shanghai Normal University, Shanghai, 200234, China
- Division of Glycoscience, Department of Chemistry, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, AlbaNova University Centre, Stockholm, SE106 91, Sweden
| | - Yves S Y Hsieh
- Division of Glycoscience, Department of Chemistry, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, AlbaNova University Centre, Stockholm, SE106 91, Sweden
- School of Pharmacy, College of Pharmacy, Taipei Medical University, Taipei, 11031, Taiwan
| | - Maenghyo Cho
- Department of Mechanical and Aerospace Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 151-742, Republic of Korea
| | - Sung-Hoon Ahn
- Department of Mechanical and Aerospace Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 151-742, Republic of Korea
| | - Chenzhe Li
- School of Aerospace Engineering and Applied Mechanics, Tongji University, 100 Zhangwu Road, Shanghai, 200092, China
- Institute of Advanced Machines and Design, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 151-742, Republic of Korea
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15
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Liu Z, Wang H, Zhou C. Synthesis and Characterization of a Liquid Crystal-Modified Polydimethylsiloxane Rubber with Mechanical Adaptability Based on Chain Extension in the Process of Crosslinking. ACS OMEGA 2022; 7:36590-36597. [PMID: 36278106 PMCID: PMC9583084 DOI: 10.1021/acsomega.2c04560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 09/16/2022] [Indexed: 06/16/2023]
Abstract
The mechanical adaptive material is a kind of functional material that can effectively dissipate energy and suppress the increase of its stress under continuous strain in a large deformation area, which are vital in artificial muscles, connection devices, soft artificial intelligence robots, and other areas. Scientists have been working to broaden the platform of the material's mechanical adaptive platform and improve its mechanical strength by specific structure design. Based on it, we expect to introduce a mechanism of energy dissipation from the molecular chain scale to further improve mechanical adaptability. We developed a liquid crystal-modified polydimethylsiloxane rubber with mechanical adaptability based on chain extension in the process of crosslinking. Results showed that liquid crystal (0.7 mol %)-modified silicone rubber can obviously dissipate energy to achieve mechanical adaptive function, and the energy dissipation ratio of polydimethylsiloxane rubber (MQ), 4-propyl-4'-vinyl-1,1'-bi(cyclohexane)-modified polydimethylsiloxane rubber (3CCV-MQ), and 4-methoxyphenyl-4-(3-butenyloxy) benzoate-modified polydimethylsiloxane rubber (MBB-MQ) gradually decreases from 30 to 24%. Excessive thiol groups of liquid crystal-modified polydimethylsiloxane react with its vinyl group to achieve the chain extension, which significantly improves the mechanical strength from 2.74 to 5.83 MPa and elongation at break from 733 to 1096%. This research offers some new insights into improving the mechanical strength of silicone rubber and is of great significance for the application of the mechanical adaptive material.
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16
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Wang Y, Sun J, Liao W, Yang Z. Liquid Crystal Elastomer Twist Fibers toward Rotating Microengines. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2107840. [PMID: 34933404 DOI: 10.1002/adma.202107840] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 12/18/2021] [Indexed: 06/14/2023]
Abstract
Untethered twist fibers do not require end-anchoring structures to hold their twist orientation and offer simple designs and convenient operation. The reversible responsiveness of these fibers allows them to generate torque and rotational deformation continuously upon the application of external stimuli. The fibers therefore have potential in rotating microengines. In practical applications, high torque and rotational deformation are desirable to meet work capacity requirements. However, the simultaneous endowment of reversible responsiveness and high rotational performance to untethered twist fibers remains a challenge. In this study, a liquid crystal elastomer twist fiber (LCETF) is designed and developed with a fixed twisting alignment of mesogens to provide untethered and reversible responsiveness. Outstanding rotational performance can be achieved when the mesogenic orientation is disrupted through heat triggering. Owing to the significant intrinsic contractile ratio of the LCE material, the rotational deformation of the LCETF can reach 243.6° mm-1 . More importantly, the specific torque can reach 10.1 N m kg-1 , which exceeds previously reported values. In addition, the LCETF can be exploited in a rotating microengine to convert heat into electricity with an induction voltage as high as 9.4 V. This work broadens the applications of LCEs for energy harvesters, micromachines, and soft robots.
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Affiliation(s)
- Yunpeng Wang
- Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Jiahao Sun
- Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Wei Liao
- Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Zhongqiang Yang
- Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Department of Chemistry, Tsinghua University, Beijing, 100084, China
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17
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Del Pozo M, Sol JAHP, Schenning APHJ, Debije MG. 4D Printing of Liquid Crystals: What's Right for Me? ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2104390. [PMID: 34716625 DOI: 10.1002/adma.202104390] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 07/20/2021] [Indexed: 05/24/2023]
Abstract
Recent years have seen major advances in the developments of both additive manufacturing concepts and responsive materials. When combined as 4D printing, the process can lead to functional materials and devices for use in health, energy generation, sensing, and soft robots. Among responsive materials, liquid crystals, which can deliver programmed, reversible, rapid responses in both air and underwater, are a prime contender for additive manufacturing, given their ease of use and adaptability to many different applications. In this paper, selected works are compared and analyzed to come to a didactical overview of the liquid crystal-additive manufacturing junction. Reading from front to back gives the reader a comprehensive understanding of the options and challenges in the field, while researchers already experienced in either liquid crystals or additive manufacturing are encouraged to scan through the text to see how they can incorporate additive manufacturing or liquid crystals into their own work. The educational text is closed with proposals for future research in this crossover field.
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Affiliation(s)
- Marc Del Pozo
- Laboratory for Stimuli-Responsive Functional Materials & Devices (SFD), Department of Chemical Engineering and Chemistry, Eindhoven University of Technology (TU/e), Groene Loper 3, Eindhoven, 5612 AE, The Netherlands
| | - Jeroen A H P Sol
- Laboratory for Stimuli-Responsive Functional Materials & Devices (SFD), Department of Chemical Engineering and Chemistry, Eindhoven University of Technology (TU/e), Groene Loper 3, Eindhoven, 5612 AE, The Netherlands
| | - Albert P H J Schenning
- Laboratory for Stimuli-Responsive Functional Materials & Devices (SFD), Department of Chemical Engineering and Chemistry, Eindhoven University of Technology (TU/e), Groene Loper 3, Eindhoven, 5612 AE, The Netherlands
- Institute for Complex Molecular Systems (ICMS), Eindhoven University of Technology, Groene Loper 3, Eindhoven, 5612 AE, The Netherlands
| | - Michael G Debije
- Laboratory for Stimuli-Responsive Functional Materials & Devices (SFD), Department of Chemical Engineering and Chemistry, Eindhoven University of Technology (TU/e), Groene Loper 3, Eindhoven, 5612 AE, The Netherlands
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18
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Wu J, Yao S, Zhang H, Man W, Bai Z, Zhang F, Wang X, Fang D, Zhang Y. Liquid Crystal Elastomer Metamaterials with Giant Biaxial Thermal Shrinkage for Enhancing Skin Regeneration. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2106175. [PMID: 34561930 DOI: 10.1002/adma.202106175] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Indexed: 06/13/2023]
Abstract
Liquid crystal elastomers (LCEs) are a class of soft active materials of increasing interest, because of their excellent actuation and optical performances. While LCEs show biomimetic mechanical properties (e.g., elastic modulus and strength) that can be matched with those of soft biological tissues, their biointegrated applications have been rarely explored, in part, due to their high actuation temperatures (typically above 60 °C) and low biaxial actuation performances (e.g., actuation strain typically below 10%). Here, unique mechanics-guided designs and fabrication schemes of LCE metamaterials are developed that allow access to unprecedented biaxial actuation strain (-53%) and biaxial coefficient of thermal expansion (-33 125 ppm K-1 ), significantly surpassing those (e.g., -20% and -5950 ppm K-1 ) reported previously. A low-temperature synthesis method with use of optimized composition ratios enables LCE metamaterials to offer reasonably high actuation stresses/strains at a substantially reduced actuation temperature (46 °C). Such biocompatible LCE metamaterials are integrated with medical dressing to develop a breathable, shrinkable, hemostatic patch as a means of noninvasive treatment. In vivo animal experiments of skin repair with both round and cross-shaped wounds demonstrate advantages of the hemostatic patch over conventional strategies (e.g., medical dressing and suturing) in accelerating skin regeneration, while avoiding scar and keloid generation.
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Affiliation(s)
- Jun Wu
- AML, Department of Engineering Mechanics, Center for Flexible Electronics Technology, Tsinghua University, Beijing, 100084, P. R. China
| | - Shenglian Yao
- School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Hang Zhang
- AML, Department of Engineering Mechanics, Center for Flexible Electronics Technology, Tsinghua University, Beijing, 100084, P. R. China
| | - Weitao Man
- Department of Neurosurgery, Beijing Tsinghua Changgung Hospital, School of Clinical Medicine, Tsinghua University, Beijing, 102218, P. R. China
| | - Zhili Bai
- School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, P. R. China
| | - Fan Zhang
- AML, Department of Engineering Mechanics, Center for Flexible Electronics Technology, Tsinghua University, Beijing, 100084, P. R. China
| | - Xiumei Wang
- School of Materials Science and Engineering, Tsinghua University, Beijing, 100084, P. R. China
| | - Daining Fang
- Institute of Advanced Structure Technology, Beijing Key Laboratory of Lightweight Multi-Functional Composite Materials and Structures, Beijing Institute of Technology, Beijing, 100081, P. R. China
| | - Yihui Zhang
- AML, Department of Engineering Mechanics, Center for Flexible Electronics Technology, Tsinghua University, Beijing, 100084, P. R. China
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