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Yao Y, He E, Xu H, Liu Y, Wei Y, Ji Y. Fabricating liquid crystal vitrimer actuators far below the normal processing temperature. MATERIALS HORIZONS 2023; 10:1795-1805. [PMID: 36857698 DOI: 10.1039/d3mh00184a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Liquid crystal vitrimers can be reprocessed, reshaped, welded, and healed due to exchange-reaction-enabled topology changes despite having fully covalently cross-linked network structures. Fabricating liquid crystal (LC) vitrimer actuators is invariably carried out above a characteristic temperature known as the topology freezing transition temperature (Tv). The reason that all exchange-reaction-based operations must be performed above Tv is because the exchange reaction is insignificant below Tv. Here we find that LC vitrimers can be reshaped at temperatures below the measured Tv, whereas non-LC vitrimers cannot. The work here not only makes it possible to create reprogrammable and stable LC vitrimer actuators at low temperatures but also reminds us that both our measurement and understanding of the Tv need further attention to facilitate the use of vitrimers in different areas.
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Affiliation(s)
- Yanjin Yao
- The Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, Department of Chemistry, Tsinghua University, China.
| | - Enjian He
- The Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, Department of Chemistry, Tsinghua University, China.
| | - Hongtu Xu
- The Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, Department of Chemistry, Tsinghua University, China.
| | - Yawen Liu
- The Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, Department of Chemistry, Tsinghua University, China.
| | - Yen Wei
- The Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, Department of Chemistry, Tsinghua University, China.
- Chung-Yuan Christian University, Chung-Li, 32023, Taiwan, China
| | - Yan Ji
- The Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, Department of Chemistry, Tsinghua University, China.
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2
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Barnes M, Cetinkaya S, Ajnsztajn A, Verduzco R. Understanding the effect of liquid crystal content on the phase behavior and mechanical properties of liquid crystal elastomers. SOFT MATTER 2022; 18:5074-5081. [PMID: 35764591 DOI: 10.1039/d2sm00480a] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Liquid crystal elastomers are stimuli-responsive, shape-shifting materials. They typically require high temperatures for actuation which prohibits their use in many applications, such as biomedical devices. In this work, we demonstrate a simple and general approach to tune the order-to-disorder transition temperature (TODT) or nematic-to-isotropic transition temperature (TNI) of LCEs through variation of the overall liquid crystal mass content. We demonstrate reduction of the TNI in nematic LCEs through the incorporation of non-mesogenic linkers or the addition of lithium salts, and show that the TNI varies linearly with liquid crystal mass content over a broad range, approximately 50 °C. We also analyze data from prior reports that include three different mesogens, different network linking chemistries, and different alignment strategies, and show that the linear trend in TODT with liquid crystal mass content also holds for these systems. Finally, we demonstrate a simple approach to quantifying the maximum actuation strain through measurement of the soft elastic plateau and demonstrate applications of nematic LCEs with low TODTs, including the first body-responsive LCE that curls around a human finger due to body heat, and a fluidic channel that directionally pumps liquid when heated.
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Affiliation(s)
- Morgan Barnes
- Department of Materials Science and NanoEngineering, Rice University, Houston, Texas, 77005, USA.
| | - Sueda Cetinkaya
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas, 77005, USA
| | - Alec Ajnsztajn
- Department of Materials Science and NanoEngineering, Rice University, Houston, Texas, 77005, USA.
| | - Rafael Verduzco
- Department of Materials Science and NanoEngineering, Rice University, Houston, Texas, 77005, USA.
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas, 77005, USA
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3
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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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4
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Basak S, Bandyopadhyay A. Styrene‐butadiene‐styrene
‐based shape memory polymers: Evolution and the current state of art. POLYM ADVAN TECHNOL 2022. [DOI: 10.1002/pat.5682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Sayan Basak
- Department of Polymer Science & Technology University of Calcutta Kolkata West Bengal India
| | - Abhijit Bandyopadhyay
- Department of Polymer Science & Technology University of Calcutta Kolkata West Bengal India
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5
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Shape memory elastomers: A review of synthesis, design, advanced manufacturing, and emerging applications. POLYM ADVAN TECHNOL 2022. [DOI: 10.1002/pat.5652] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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6
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7
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Yang J, Gong J, Tao L, Tang Z, Yang Z, Cao P, Wang Q, Wang T, Luo H, Zhang Y. Reconfigurable and NIR-responsive shape memory polymer containing bipheunit units and graphene. Polym J 2022. [DOI: 10.1038/s41428-021-00609-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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8
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Li Y, Keum JK, Wang J, Jiang N, Bras W, Kessler MR, Rios O. Multiscale Structural Characterization of a Smectic Liquid Crystalline Elastomer upon Mechanical Deformation Using Neutron Scattering. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c01622] [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)
- Yuzhan Li
- School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Jong K. Keum
- Center for Nanophase Materials Sciences and Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Jun Wang
- School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Naisheng Jiang
- School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Wim Bras
- Chemical Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Michael R. Kessler
- Department of Mechanical Engineering, North Dakota State University, Fargo, North Dakota 58108, United States
| | - Orlando Rios
- Department of Materials Science and Engineering, The University of Tennessee, Knoxville, Tennessee 37996, United States
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9
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Karausta A, Kocaman C, Bukusoglu E. Controlling the shapes and internal complexity of the polymeric particles using liquid crystal-templates confined into microwells. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2020.114710] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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10
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Li Y, Goswami M, Zhang Y, Liu T, Zhang J, Kessler MR, Wang L, Rios O. Combined light- and heat-induced shape memory behavior of anthracene-based epoxy elastomers. Sci Rep 2020; 10:20214. [PMID: 33214668 PMCID: PMC7677552 DOI: 10.1038/s41598-020-77246-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 11/03/2020] [Indexed: 11/27/2022] Open
Abstract
The development of multi-stimuli-responsive shape memory polymers has received increasing attention because of its scientific and technological significance. In this work, epoxy elastomers with reversible crosslinks are synthesized by polymerizing an anthracene-functionalized epoxy monomer, a diepoxy comonomer, and a dicarboxylic acid curing agent. The synthesized elastomers exhibit active responses to both light and heat enabled by the incorporated anthracene groups. When exposed to 365 nm UV light, additional crosslinking points are created by the photo-induced dimerization of pendant anthracene groups. The formation of the crosslinking points increases modulus and glass transition temperature of the elastomers, allowing for the fixation of a temporary shape at room temperature. The temporary shape remains stable until an external heat stimulus is applied to trigger the scission of the dimerized anthracene, which reduces the modulus and glass transition temperature and allows the elastomers to recover their original shapes. The effects of external stimuli on the thermal and dynamic mechanical properties of the elastomers are investigated experimentally and are correlated with molecular dynamics simulations that reveal the changes of structure and dynamics of the anthracene molecules and flexible chains.
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Affiliation(s)
- Yuzhan Li
- Energy and Transportation Science Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Monojoy Goswami
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Yuehong Zhang
- College of Bioresources Chemical and Materials Engineering, Shaanxi University of Science and Technology, Xi'an, 710021, China
| | - Tuan Liu
- School of Mechanical and Materials Engineering, Washington State University, Pullman, WA, 99164, USA
| | - Jinwen Zhang
- School of Mechanical and Materials Engineering, Washington State University, Pullman, WA, 99164, USA
| | - Michael R Kessler
- Department of Mechanical Engineering, North Dakota State University, Fargo, ND, 58108, USA
| | - Liwei Wang
- School of Mechanical and Materials Engineering, Washington State University, Pullman, WA, 99164, USA.
| | - Orlando Rios
- Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN, 37996, USA.
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11
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Chen Y, Chen C, Rehman HU, Zheng X, Li H, Liu H, Hedenqvist MS. Shape-Memory Polymeric Artificial Muscles: Mechanisms, Applications and Challenges. Molecules 2020; 25:E4246. [PMID: 32947872 PMCID: PMC7570610 DOI: 10.3390/molecules25184246] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 08/27/2020] [Accepted: 09/03/2020] [Indexed: 11/16/2022] Open
Abstract
Shape-memory materials are smart materials that can remember an original shape and return to their unique state from a deformed secondary shape in the presence of an appropriate stimulus. This property allows these materials to be used as shape-memory artificial muscles, which form a subclass of artificial muscles. The shape-memory artificial muscles are fabricated from shape-memory polymers (SMPs) by twist insertion, shape fixation via Tm or Tg, or by liquid crystal elastomers (LCEs). The prepared SMP artificial muscles can be used in a wide range of applications, from biomimetic and soft robotics to actuators, because they can be operated without sophisticated linkage design and can achieve complex final shapes. Recently, significant achievements have been made in fabrication, modelling, and manipulation of SMP-based artificial muscles. This paper presents a review of the recent progress in shape-memory polymer-based artificial muscles. Here we focus on the mechanisms of SMPs, applications of SMPs as artificial muscles, and the challenges they face concerning actuation. While shape-memory behavior has been demonstrated in several stimulated environments, our focus is on thermal-, photo-, and electrical-actuated SMP artificial muscles.
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Affiliation(s)
- Yujie Chen
- State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China; (Y.C.); (C.C.); (X.Z.)
| | - Chi Chen
- State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China; (Y.C.); (C.C.); (X.Z.)
| | - Hafeez Ur Rehman
- State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China; (Y.C.); (C.C.); (X.Z.)
| | - Xu Zheng
- State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China; (Y.C.); (C.C.); (X.Z.)
| | - Hua Li
- Collaborative Innovation Centre for Advanced Ship and Dee-Sea Exploration, Shanghai Jiao Tong University, Shanghai 200240, China; (H.L.); (H.L.)
| | - Hezhou Liu
- Collaborative Innovation Centre for Advanced Ship and Dee-Sea Exploration, Shanghai Jiao Tong University, Shanghai 200240, China; (H.L.); (H.L.)
| | - Mikael S. Hedenqvist
- Department of Fibre and Polymer Technology, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden
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12
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Lyu X, Xiao A, Shi D, Li Y, Shen Z, Chen EQ, Zheng S, Fan XH, Zhou QF. Liquid crystalline polymers: Discovery, development, and the future. POLYMER 2020. [DOI: 10.1016/j.polymer.2020.122740] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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13
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Hoekstra DC, Schenning APHJ, Debije MG. Epoxide and oxetane based liquid crystals for advanced functional materials. SOFT MATTER 2020; 16:5106-5119. [PMID: 32459272 DOI: 10.1039/d0sm00489h] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Liquid crystalline elastomers (LCEs) and liquid crystalline networks (LCNs) are classes of polymers very suitable for fabricating advanced functional materials. Two main pathways to obtain LCEs and LCNs have gained the most attention in the literature, namely the two-step crosslinking of LC side-chain polymers and the photoinitiated free-radical polymerisation of acrylate LC monomers. These liquid crystal polymers have demonstrated remarkable properties resulting from their anisotropic shapes, being used in soft robotics, responsive surfaces and as photonic materials. In this review, we will show that LCs with cyclic ethers as polymerisable groups can be an attractive alternative to the aforementioned reactive acrylate mesogens. These epoxide and oxetane based reactive mesogens could offer a number of advantages over their acrylate-based counterparts, including oxygen insensitivity, reduced polymerisation shrinkage, improved alignment, lower processing viscosity and potentially extended resistivity. In this review, we summarise the research on these materials from the past 30 years and offer a glimpse into the potential of these cyclic ether mesogens.
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Affiliation(s)
- Davey C Hoekstra
- Laboratory of Stimuli-responsive Functional Materials and Devices, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Groene Loper 5, 5612 AE Eindhoven, The Netherlands. and Institute for Complex Molecular Systems, Eindhoven University of Technology, Groene Loper 5, 5612 AE Eindhoven, The Netherlands
| | - Albert P H J Schenning
- Laboratory of Stimuli-responsive Functional Materials and Devices, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Groene Loper 5, 5612 AE Eindhoven, The Netherlands. and Institute for Complex Molecular Systems, Eindhoven University of Technology, Groene Loper 5, 5612 AE Eindhoven, The Netherlands
| | - Michael G Debije
- Laboratory of Stimuli-responsive Functional Materials and Devices, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Groene Loper 5, 5612 AE Eindhoven, The Netherlands.
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14
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Li Y, Zhang Y, Goswami M, Vincent D, Wang L, Liu T, Li K, Keum JK, Gao Z, Ozcan S, Gluesenkamp KR, Rios O, Kessler MR. Liquid crystalline networks based on photo-initiated thiol-ene click chemistry. SOFT MATTER 2020; 16:1760-1770. [PMID: 31859322 DOI: 10.1039/c9sm01818b] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Photo-initiated thiol-ene click chemistry is used to develop shape memory liquid crystalline networks (LCNs). A biphenyl-based di-vinyl monomer is synthesized and cured with a di-thiol chain extender and a tetra-thiol crosslinker using UV light. The effects of photo-initiator concentration and UV light intensity on the curing behavior and liquid crystalline (LC) properties of the LCNs are investigated. The chemical composition is found to significantly influence the microstructure and the related thermomechanical properties of the LCNs. The structure-property relationship is further explored using molecular dynamics simulations, revealing that the introduction of the chain extender promotes the formation of an ordered smectic LC phase instead of agglomerated structures. The concentration of the chain extender affects the liquid crystallinity of the LCNs, resulting in distinct thermomechanical and shape memory properties. This class of LCNs exhibits fast curing rates, high conversion levels, and tailorable liquid crystallinity, making it a promising material system for advanced manufacturing, where complex and highly ordered structures can be produced with fast reaction kinetics and low energy consumption.
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Affiliation(s)
- Yuzhan Li
- Materials Science and Technology Division, Oak Ridge National Laboratory, 1 Bethel Valley Rd, Oak Ridge, TN 37831, USA.
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15
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Akdeniz B, Bukusoglu E. Design Parameters and Principles of Liquid-Crystal-Templated Synthesis of Polymeric Materials via Photolithography. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:13126-13134. [PMID: 31517498 DOI: 10.1021/acs.langmuir.9b02293] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The design parameters and principles for the synthesis of polymeric microscopic objects using a method that combines photolithography and liquid crystal (LC) molecular templates have been demonstrated. Specifically, mixtures of a reactive mesogen (RM257) and nonreactive LC (E7) were polymerized using UV light and a photomask. We used photomasks with circular, triangular, rectangular, square, star-shaped, and heart-shaped features to provide initial shapes to the objects. Then, the unreacted parts were extracted and the polymeric objects were allowed to shrink anisotropically as defined by the ordering symmetry of the LC mixture. The initial configuration of the LC mixtures played a critical role in determining the final shapes of the polymeric objects formed after shrinking, which resulted in chiral twisting and bending, leading to more than 20 different shapes. We found that the pitch size of the bulk chiral twisted objects depends linearly on the angle of chiral twist of the LCs, whereas it was independent of their thickness and length ranging from 1.5 to 160 μm and 100 μm to 2.45 cm, respectively. The shapes of the polymeric objects synthesized from LC films with bent LC ordering, however, were critically dependent on the thickness of the objects due to the interplay between the elastic energy and surface anchoring of the LCs. The critical role of LC elasticity was observed for thicknesses below 20 μm, above which surface anchoring was dominant in determining the shapes. Overall, the proposed method was shown to provide a precise control over the three-dimensional architectures of the objects with size range that covers the micro and macro scales, which would find use in fields ranging from emulsion stabilization and catalysis to micromachines and artificial muscles.
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Affiliation(s)
- Burak Akdeniz
- Department of Chemical Engineering , Middle East Technical University , Dumlupınar Bulvarı No. 1 , Çankaya, Ankara 06800 , Turkey
| | - Emre Bukusoglu
- Department of Chemical Engineering , Middle East Technical University , Dumlupınar Bulvarı No. 1 , Çankaya, Ankara 06800 , Turkey
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16
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Zhu Y, Radlauer MR, Schneiderman DK, Shaffer MSP, Hillmyer MA, Williams CK. Multiblock Polyesters Demonstrating High Elasticity and Shape Memory Effects. Macromolecules 2018. [DOI: 10.1021/acs.macromol.7b02690] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Yunqing Zhu
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3TA, U.K
| | - Madalyn R. Radlauer
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455-0431, United States
| | - Deborah K. Schneiderman
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455-0431, United States
| | | | - Marc A. Hillmyer
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455-0431, United States
| | - Charlotte K. Williams
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3TA, U.K
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17
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Yoon HH, Kim DY, Jeong KU, Ahn SK. Surface Aligned Main-Chain Liquid Crystalline Elastomers: Tailored Properties by the Choice of Amine Chain Extenders. Macromolecules 2018. [DOI: 10.1021/acs.macromol.7b02514] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Hyeong-Ho Yoon
- Department
of Polymer Science and Engineering, Pusan National University, Busan, Korea 46241
| | - Dae-Yoon Kim
- BK21 Plus Haptic Polymer Composite Research Team & Department of Polymer-Nano Science and Technology, Chonbuk National University, Jeonju, Korea 54896
| | - Kwang-Un Jeong
- BK21 Plus Haptic Polymer Composite Research Team & Department of Polymer-Nano Science and Technology, Chonbuk National University, Jeonju, Korea 54896
| | - Suk-kyun Ahn
- Department
of Polymer Science and Engineering, Pusan National University, Busan, Korea 46241
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18
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Belmonte A, Lama GC, Gentile G, Cerruti P, Ambrogi V, Fernández-Francos X, De la Flor S. Thermally-triggered free-standing shape-memory actuators. Eur Polym J 2017. [DOI: 10.1016/j.eurpolymj.2017.10.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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19
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Traugutt NA, Volpe RH, Bollinger MS, Saed MO, Torbati AH, Yu K, Dadivanyan N, Yakacki CM. Liquid-crystal order during synthesis affects main-chain liquid-crystal elastomer behavior. SOFT MATTER 2017; 13:7013-7025. [PMID: 28930352 DOI: 10.1039/c7sm01405h] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
This study presents the first direct comparison of the influence of liquid-crystal order during synthesis on the thermo-mechanical behaviors of main-chain liquid-crystal elastomers (LCEs) in thiol-acrylate networks. Six polydomain nematic elastomer (PNE) chemistries were compared directly by synthesizing with the mesogens in either an isotropic state (i-PNE) or a nematic state (n-PNE). The i-PNE networks were created in the presence of solvent, which disrupted any liquid-crystal order during network formation. Conversely, the n-PNE networks were created without the presence of solvent below the isotropic transition (TNI). Differential scanning calorimetry (DSC) was first performed, and it showed that i-PNE networks experienced a clearly defined nematic-to-isotropic transition upon heating, whereas the transition in n-PNE networks was unable to be identified, which may be the result of a nematic-to-paranematic phase transition. Dynamic mechanical analysis (DMA) tests revealed that while both networks maintained elevated loss tangent in the nematic region, only i-PNE networks prominently displayed dynamic soft elasticity behavior. The two-way shape switching behaviors of LCE networks were examined using actuation tests under a 100 kPa bias stress. It showed that the strain amplitude strongly depends on synthesis history; it ranges from 66% to 126% in i-PNE samples and 3% to 61% in n-PNE samples. To help interpret the different actuation strain behaviors between i-PNEs and n-PNEs, wide-angle X-ray scattering (WAXS) was then performed where the LCE samples were strained to 40%. The results showed that order parameter (S) in n-PNE samples (ranging from 0.37 to 0.50) is lower than that in i-PNE samples (0.54 for all cases), and the parameter decreased as the cross-linking density increased. The stress-strain behaviors of the LCE networks measured from uniaxial tension tests revealed that all i-PNE samples had a lower soft-elasticity plateau during loading compared to the n-PNE samples. Finally, free-standing strain recovery of LCE samples after being strained to 100% was investigated. Immediately after removing stress on the samples, i-PNE and n-PNE samples recovered 14% to 38% and 27% to 73% of strain, respectively. We discuss the advantages and disadvantages of the different synthetic histories on LCE design.
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Affiliation(s)
- N A Traugutt
- Smart Materials and Biomechanics Lab, Mechanical Engineering, University of Colorado Denver, Denver, CO 80217, USA.
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20
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Kularatne RS, Kim H, Boothby JM, Ware TH. Liquid crystal elastomer actuators: Synthesis, alignment, and applications. ACTA ACUST UNITED AC 2017. [DOI: 10.1002/polb.24287] [Citation(s) in RCA: 186] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Ruvini S. Kularatne
- Department of Bioengineering; University of Texas at Dallas; 800 W. Campbell Rd. Richardson Texas 75080 USA
| | - Hyun Kim
- Department of Bioengineering; University of Texas at Dallas; 800 W. Campbell Rd. Richardson Texas 75080 USA
| | - Jennifer M. Boothby
- Department of Bioengineering; University of Texas at Dallas; 800 W. Campbell Rd. Richardson Texas 75080 USA
| | - Taylor H. Ware
- Department of Bioengineering; University of Texas at Dallas; 800 W. Campbell Rd. Richardson Texas 75080 USA
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21
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Saed MO, Torbati AH, Starr CA, Visvanathan R, Clark NA, Yakacki CM. Thiol-acrylate main-chain liquid-crystalline elastomers with tunable thermomechanical properties and actuation strain. ACTA ACUST UNITED AC 2016. [DOI: 10.1002/polb.24249] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Mohand O. Saed
- Department of Mechanical Engineering; University of Colorado Denver; Denver Colorado 80217
| | - Amir H. Torbati
- Department of Mechanical Engineering; University of Colorado Denver; Denver Colorado 80217
| | - Chelsea A. Starr
- Department of Mechanical Engineering; University of Colorado Denver; Denver Colorado 80217
| | - Rayshan Visvanathan
- Department of Physics; Soft Materials Research Center, University of Colorado Boulder; Boulder Colorado 80309
| | - Noel A. Clark
- Department of Physics; Soft Materials Research Center, University of Colorado Boulder; Boulder Colorado 80309
| | - Christopher M. Yakacki
- Department of Mechanical Engineering; University of Colorado Denver; Denver Colorado 80217
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22
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Chung H, Park J, Cho M. Numerical study of light-induced phase behavior of smectic solids. Phys Rev E 2016; 94:042707. [PMID: 27841478 DOI: 10.1103/physreve.94.042707] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2016] [Indexed: 06/06/2023]
Abstract
By the chemical cross-linking of rigid molecules, liquid crystal polymer (LCP) has been envisaged as a novel heterogeneous material due to the fact that various optical and geometric states of the liquid crystalline (LC) phases are projected onto the polymeric constituents. The phase behavior, which refers to the macroscopic shape change of LCP under thermotropic phase change, is a compelling example of such optical-mechanical coupling. In this study, the photomechanical behavior, which broadly refers to the thermal- or light-induced actuation of smectic solids, is investigated using three-dimensional nonlinear finite element analysis (FEA). First, the various phases of LC are considered as well as their relation to polymeric conformation defined by the strain energy of the smectic polymer; a comprehensive constitutive equation that bridges the strong, optomechanical coupling is then derived. Such photomechanical coupling is incorporated in the FEA considering geometric nonlinearity, which is vital to understanding the large-scale light-induced bending behavior of the smectic solid.To demonstrate the simulation capability of the present model, numerous examples of photomechanical deformations are investigated parametrically, either by changing the operating conditions such as stimuli (postsynthesis) or the intrinsic properties (presynthesis). When compared to nematic solids, distinguished behaviors due to smectic substances are found herein and discussed through experiments. The quasisoftness that bidirectionally couples microscopic variables to mechanical behavior is also explained, while considering the effect of nonlinearity. In addition to providing a comprehensive measure that could deepen the knowledge of photomechanical coupling, the use of the proposed finite element framework offers an insight into the design of light-responsive actuating systems made of smectic solids.
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Affiliation(s)
- Hayoung Chung
- Divison of Multiscale Mechanical Design, School of Mechanical and Aerospace Engineering, Seoul National University, San 56-1, Shillim-Dong, Kwanak-Ku, Seoul 151-744, South Korea
| | - Jaesung Park
- Divison of Multiscale Mechanical Design, School of Mechanical and Aerospace Engineering, Seoul National University, San 56-1, Shillim-Dong, Kwanak-Ku, Seoul 151-744, South Korea
| | - Maenghyo Cho
- Divison of Multiscale Mechanical Design, School of Mechanical and Aerospace Engineering, Seoul National University, San 56-1, Shillim-Dong, Kwanak-Ku, Seoul 151-744, South Korea
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23
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Li Y, Rios O, Keum JK, Chen J, Kessler MR. Photoresponsive Liquid Crystalline Epoxy Networks with Shape Memory Behavior and Dynamic Ester Bonds. ACS APPLIED MATERIALS & INTERFACES 2016; 8:15750-15757. [PMID: 27245744 DOI: 10.1021/acsami.6b04374] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Functional polymers are intelligent materials that can respond to a variety of external stimuli. However, these materials have not yet found widespread real world applications because of the difficulties in fabrication and the limited number of functional building blocks that can be incorporated into a material. Here, we demonstrate a simple route to incorporate three functional building blocks (azobenzene chromophores, liquid crystals, and dynamic covalent bonds) into an epoxy-based liquid crystalline network (LCN), in which an azobenzene-based epoxy monomer is polymerized with an aliphatic dicarboxylic acid to create exchangeable ester bonds that can be thermally activated. All three functional building blocks exhibited good compatibility, and the resulting materials exhibits various photomechanical, shape memory, and self-healing properties because of the azobenzene molecules, liquid crystals, and dynamic ester bonds, respectively.
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Affiliation(s)
- Yuzhan Li
- School of Mechanical and Materials Engineering, Washington State University , PO Box 642920, Pullman, Washington 99164-2920, United States
| | - Orlando Rios
- Deposition Sciences Group, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
| | - Jong K Keum
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
| | - Jihua Chen
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
| | - Michael R Kessler
- School of Mechanical and Materials Engineering, Washington State University , PO Box 642920, Pullman, Washington 99164-2920, United States
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24
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Wei L, McDonald AG. Accelerated weathering studies on the bioplastic, poly(3-hydroxybutyrate-co-3-hydroxyvalerate). Polym Degrad Stab 2016. [DOI: 10.1016/j.polymdegradstab.2016.01.023] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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