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Herman JA, Hoang JD, White TJ. Elastocaloric Response of Isotropic Liquid Crystalline Elastomers. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20: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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2
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Nan Z, Wei W, Lin Z, Chang J, Hao Y. Flexible Nanocomposite Conductors for Electromagnetic Interference Shielding. NANO-MICRO LETTERS 2023; 15:172. [PMID: 37420119 PMCID: PMC10328908 DOI: 10.1007/s40820-023-01122-5] [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: 03/27/2023] [Accepted: 05/02/2023] [Indexed: 07/09/2023]
Abstract
HIGHLIGHTS Convincing candidates of flexible (stretchable/compressible) electromagnetic interference shielding nanocomposites are discussed in detail from the views of fabrication, mechanical elasticity and shielding performance. Detailed summary of the relationship between deformation of materials and electromagnetic shielding performance. The future directions and challenges in developing flexible (particularly elastic) shielding nanocomposites are highlighted. With the extensive use of electronic communication technology in integrated circuit systems and wearable devices, electromagnetic interference (EMI) has increased dramatically. The shortcomings of conventional rigid EMI shielding materials include high brittleness, poor comfort, and unsuitability for conforming and deformable applications. Hitherto, flexible (particularly elastic) nanocomposites have attracted enormous interest due to their excellent deformability. However, the current flexible shielding nanocomposites present low mechanical stability and resilience, relatively poor EMI shielding performance, and limited multifunctionality. Herein, the advances in low-dimensional EMI shielding nanomaterials-based elastomers are outlined and a selection of the most remarkable examples is discussed. And the corresponding modification strategies and deformability performance are summarized. Finally, expectations for this quickly increasing sector are discussed, as well as future challenges.
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Affiliation(s)
- Ze Nan
- State Key Discipline Laboratory of Wide Band Gap Semiconductor Technology, School of Microelectronics, Xidian University, 2 South Taibai Road, Xi'an, 710071, People's Republic of China
| | - Wei Wei
- State Key Discipline Laboratory of Wide Band Gap Semiconductor Technology, School of Microelectronics, Xidian University, 2 South Taibai Road, Xi'an, 710071, People's Republic of China.
- Advanced Interdisciplinary Research Center for Flexible Electronics, Xidian University, 2 South Taibai Road, Xi'an, 710071, People's Republic of China.
| | - Zhenhua Lin
- State Key Discipline Laboratory of Wide Band Gap Semiconductor Technology, School of Microelectronics, Xidian University, 2 South Taibai Road, Xi'an, 710071, People's Republic of China
| | - Jingjing Chang
- State Key Discipline Laboratory of Wide Band Gap Semiconductor Technology, School of Microelectronics, Xidian University, 2 South Taibai Road, Xi'an, 710071, People's Republic of China.
- Advanced Interdisciplinary Research Center for Flexible Electronics, Xidian University, 2 South Taibai Road, Xi'an, 710071, People's Republic of China.
| | - Yue Hao
- State Key Discipline Laboratory of Wide Band Gap Semiconductor Technology, School of Microelectronics, Xidian University, 2 South Taibai Road, Xi'an, 710071, People's Republic of China
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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: 3] [Impact Index Per Article: 3.0] [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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Park M, Stricker F, Campos JG, Clark KD, Lee J, Kwon Y, Valentine MT, Read de Alaniz J. Design of Surface-Aligned Main-Chain Liquid-Crystal Networks Prepared under Ambient, Light-Free Conditions Using the Diels-Alder Cycloaddition. ACS Macro Lett 2023; 12:33-39. [PMID: 36541858 DOI: 10.1021/acsmacrolett.2c00616] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Surface-aligned liquid-crystal networks (LCNs) offer a solution for developing functional materials capable of performing a range of tasks, including actuation, shape memory, and surfaces patterning. Here we show that Diels-Alder cycloaddition can be used to prepare the backbone of planar aligned LCNs under mild ambient conditions without the addition of additives or UV irradiation. The mechanical properties of the networks have robust viscoelastic modulus and stiffness with a reversible local free volume change upon physical aging. This study shows new opportunities to design surface-aligned LCNs based on additive free step-growth Diels-Alder polymerization and enables the potential to incorporate a wider range of photochromic materials into LCNs.
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Affiliation(s)
- Minwook Park
- Department of Chemistry and Biochemistry, University of California at Santa Barbara, Santa Barbara 93106, California, United States
| | - Friedrich Stricker
- Department of Chemistry and Biochemistry, University of California at Santa Barbara, Santa Barbara 93106, California, United States
| | - Jesus Guillen Campos
- Department of Chemistry and Biochemistry, University of California at Santa Barbara, Santa Barbara 93106, California, United States
| | - Kyle D Clark
- Department of Chemistry and Biochemistry, University of California at Santa Barbara, Santa Barbara 93106, California, United States
| | - Jaejun Lee
- Department of Polymer Science and Engineering, Pusan National University, Busan 46241, Republic of Korea
| | - Younghoon Kwon
- Department of Mechanical Engineering, University of California-Santa Barbara, Santa Barbara 93106, California, United States
| | - Megan T Valentine
- Department of Mechanical Engineering, University of California-Santa Barbara, Santa Barbara 93106, California, United States
| | - Javier Read de Alaniz
- Department of Chemistry and Biochemistry, University of California at Santa Barbara, Santa Barbara 93106, California, United States
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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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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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Liu Z, Wang H, Zhou C. The Effect of Phenyl Content on the Liquid Crystal-Based Organosilicone Elastomers with Mechanical Adaptability. Polymers (Basel) 2022; 14:903. [PMID: 35267724 PMCID: PMC8912632 DOI: 10.3390/polym14050903] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 02/21/2022] [Accepted: 02/23/2022] [Indexed: 12/02/2022] Open
Abstract
An elastomer with mechanical adaptability is a new kind of polymer material in which the increasing stress under continuous deformation is significantly inhibited in a large deformation area. Liquid crystal-based organosilicone elastomers, which can dissipate energy through reversible internal phase transition under external stimulation and have recoverable large deformation capacity, have drawn much interest as mechanical adaptability materials. However, there is no good way to control the mechanical adaptability at present. For this purpose, we prepared a new liquid crystal-based phenyl silicone rubber (LCMVPQ) using two-step click reactions and systematically explored the effect of phenyl content on its mechanical adaptability to achieve the regulation of mechanical adaptability. With an increase in phenyl content in the LCMVPQs, phenyl can hinder the rearrangement of the mesogenic units along the applied stress direction, which enables the adjustment of mechanical adaptability to meet the needs of different situations. In addition, the introduction of the liquid crystal phase impedes the internal friction of the molecular chain movement of the LCMVPQs and reduces the damping performance of silicone rubber. This research achieves the regulation of elastomers with mechanical adaptability and is expected to be applied in practical application fields.
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Affiliation(s)
| | | | - Chuanjian Zhou
- School of Materials Science and Engineering, Shandong University, Jinan 250061, China; (Z.L.); (H.W.)
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Liu Z, Xiong Y, Hao J, Zhang H, Cheng X, Wang H, Chen W, Zhou C. Liquid Crystal-Based Organosilicone Elastomers with Supreme Mechanical Adaptability. Polymers (Basel) 2022; 14:789. [PMID: 35215702 PMCID: PMC8880581 DOI: 10.3390/polym14040789] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 01/30/2022] [Accepted: 02/03/2022] [Indexed: 02/04/2023] Open
Abstract
Elastomers with supreme mechanical adaptability where the increasing stress under continuous deformation is significantly inhibited within a large deformation zone, are highly desired in many areas, such as artificial muscles, flexible and wearable electronics, and soft artificial-intelligence robots. Such system comprises the advantages of recoverable elasticity and internal compensation to external mechanical work. To obtain elastomer with supreme mechanical adaptability, a novel liquid crystal-based organosilicon elastomer (LCMQ) is developed in this work, which takes the advantages of reversible strain-induced phase transition of liquid crystal units in polymer matrix and the recoverable nano-sized fillers. The former is responsible for the inhibition of stress increasing during deformation, where the external work is mostly compensated by internal phase transition, and the latter provides tunable and sufficient high tensile strength. Such LCMQs were synthesized with 4-methoxyphenyl 4-(but-3-en-1-yloxy)benzoate (MBB) grafted thiol silicone oil (crosslinker-g-MBB) as crosslinking agent, vinyl terminated polydimethylsiloxane as base adhesive, and fumed silica as reinforcing filler by two-step thiol-ene "click" reaction. The obtained tensile strength and the elongation at break are better than previously reported values. Moreover, the resulting liquid crystal elastomers exhibit different mechanical behavior from conventional silicone rubbers. When the liquid crystal content increases from 1% (w/w) to 4% (w/w), the stress plateau for mechanical adaptability becomes clearer. Moreover, the liquid crystal elastomer has no obvious deformation from 25 °C to 120 °C and is expected to be used in industrial applications. It also provides a new template for the modification of organosilicon elastomers.
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Affiliation(s)
- Zhe Liu
- School of Materials Science and Engineering, Shandong University, Jinan 250061, China; (Z.L.); (J.H.); (H.Z.); (X.C.); (H.W.)
| | - Yuqi Xiong
- CAS Key Laboratory of Soft Matter Chemistry, University of Science and Technology of China, Hefei 230026, China;
| | - Jinghao Hao
- School of Materials Science and Engineering, Shandong University, Jinan 250061, China; (Z.L.); (J.H.); (H.Z.); (X.C.); (H.W.)
| | - Hao Zhang
- School of Materials Science and Engineering, Shandong University, Jinan 250061, China; (Z.L.); (J.H.); (H.Z.); (X.C.); (H.W.)
| | - Xiao Cheng
- School of Materials Science and Engineering, Shandong University, Jinan 250061, China; (Z.L.); (J.H.); (H.Z.); (X.C.); (H.W.)
| | - Hua Wang
- School of Materials Science and Engineering, Shandong University, Jinan 250061, China; (Z.L.); (J.H.); (H.Z.); (X.C.); (H.W.)
| | - Wei Chen
- CAS Key Laboratory of Soft Matter Chemistry, University of Science and Technology of China, Hefei 230026, China;
| | - Chuanjian Zhou
- School of Materials Science and Engineering, Shandong University, Jinan 250061, China; (Z.L.); (J.H.); (H.Z.); (X.C.); (H.W.)
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Yao M, Wu B, Feng X, Sun S, Wu P. A Highly Robust Ionotronic Fiber with Unprecedented Mechanomodulation of Ionic Conduction. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2103755. [PMID: 34477247 DOI: 10.1002/adma.202103755] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 07/14/2021] [Indexed: 06/13/2023]
Abstract
Stretchable ionic conductors are appealing for tissue-like soft electronics, yet suffer from a tardy mechanoelectric response due to their poor modulation of ionic conduction arising from intrinsic homogeneous soft chain network. Here, a highly robust ionotronic fiber is designed by synergizing ionic liquid and liquid crystal elastomer with alternate rigid mesogen units and soft chain spacers, which shows an unprecedented strain-induced ionic conductivity boost (≈103 times enhanced as stretched to 2000% strain). Such a surprisingly high enhancement is attributed to the formation of microphase-separated low-tortuosity ion-conducting nanochannels guided by strain-induced emergence of aligned smectic mesophases, thus allowing for ultrafast ion transport that resembles the role of "swimming lanes." Intriguingly, the boosting conductivity even reverses Pouillet's Law-dictated resistance increase at certain strains, leading to unique waveform-discernible strain sensing. Moreover, the fiber retains thermal actuation properties with a maximum of 70% strain changes upon heating, and enables integrated self-perception and actuation. The findings offer a promising molecular engineering route to mechanically modulate the ion transport behavior of ionic conductors toward advanced ionotronic applications.
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Affiliation(s)
- Mingyue Yao
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Chemistry, Chemical Engineering and Biotechnology & Center for Advanced Low-dimension Materials, Donghua University, 2999 North Renmin Road, Shanghai, 201620, China
| | - Baohu Wu
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ) Forschungszentrum Jülich, Lichtenbergstr. 1, 85748, Garching, Germany
| | - Xunda Feng
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Chemistry, Chemical Engineering and Biotechnology & Center for Advanced Low-dimension Materials, Donghua University, 2999 North Renmin Road, Shanghai, 201620, China
| | - Shengtong Sun
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Chemistry, Chemical Engineering and Biotechnology & Center for Advanced Low-dimension Materials, Donghua University, 2999 North Renmin Road, Shanghai, 201620, China
| | - Peiyi Wu
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Chemistry, Chemical Engineering and Biotechnology & Center for Advanced Low-dimension Materials, Donghua University, 2999 North Renmin Road, Shanghai, 201620, China
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