Two-step crosslinked liquid-crystalline elastomer with reversible two-way shape memory characteristics

Yu-chang, Wang; Huang, Xuezhen; Zhang, Jianqi; Meng, Bo; Zhang, Jindi; Huang, Niu; Li, Chensha; Yu, Haifeng; Wang, Binsong; Jiang, Hongrui

doi:10.1080/15421406.2017.1318025

Cited by 18 publications

(17 citation statements)

References 46 publications

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“…The alignment effect of the LC mesogens in AZO-CLCP/CNT nanocomposite films cannot be measured by POM due to their opacity. Figure 3b shows the 2D-WAXS pattern of an AZO-CLCP/CNT nanocomposite film measured with the incident beam perpendicular to the film surface, the azimuthal intensity maxima at wide-angle reflection indicate the alignment structure of LC mesogens in a CLCP matrix [35,41]. The 2D-WAXS patterns of the AZO-CLCP/CNT nanocomposite films with different molar ratio of DA11AB to C9A also exhibited consistent result that the locations of the wide-angle reflection were orthogonal to the rubbing directions of the alignment layers, thus further confirming the LC alignment structure of CLCP matrices, and that the LC mesogenic units were well aligned along the rubbing directions of the alignment layers.…”

Section: Resultsmentioning

confidence: 99%

“…Carbon nanotubes (CNTs) and graphene-typed materials have been widely studied for their extraordinary physical properties, such as good absorption in the visible/near-infrared region, high mechanical strengths and conductivities, etc [31]. Therefore, CNTs and graphene-typed materials have been successfully incorporated into CLCPs and LCEs to improve the materials’ mechanical properties, and their unique photo-thermal conversion effect and high thermal conductivities make them efficient nanoscale heaters to generate localized heating upon light irradiation, thereby inducing the LC-to-isotropy phase transition of matrices, and hence the reversible deformation of CLCP or LCE materials [27,28,29,30,32,33,34,35,36,37,38,39,40,41]. CNTs can obviously affect the structure and property of incorporated organic molecules by noncovalent interactions [31], it has been reported that the CNTs with aligned nanostructure could effectively orient the mesogens of CLCPs along the axis of CNTs [42].…”

Section: Introductionmentioning

confidence: 99%

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Photo Actuation Performance of Nanotube Sheet Incorporated Azobenzene Crosslinked Liquid Crystalline Polymer Nanocomposite

Meng

Yu-chang

et al. 2019

Polymers

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Crosslinked liquid crystalline polymers (CLCPs) containing azobenzene (AZO-CLCPs) are a type of promising material due to their significance in the design of light-driven smart actuators. Developing AZO-CLCP composites by incorporating AZO-CLCPs with other materials is an effective way of enhancing their practicability. Herein, we report an AZO-CLCP/CNT nanocomposite prepared by the in situ polymerization of diacrylates containing azobenzene chromophores on carbon nanotube (CNT) sheets. The liquid crystal phase structure of CLCP matrix was evidenced by the two-dimensional X-ray scattering. The prepared pure AZO-CLCP films and AZO-CLCP/CNT nanocomposite films demonstrated strong reversible photo-triggered deformation under the irradiation of UV light at 366 nm of wavelength, as a result of photo-induced isomerization of azobenzene moieties in the polymer network. But compared to pure AZO-CLCP films, the AZO-CLCP/CNT nanocomposite films could much more rapidly return to their initial shapes after the UV light irradiation was removed due to the elasticity effect of CNT sheets. The deformation behavior of AZO-CLCP/CNT nanocomposite films under the light irradiation was also different from that of the pure AZO-CLCP films due to the interfacial interaction between a polymer network and CNT sheet. Furthermore, incorporation of a CNT sheet remarkably increased the mechanical strength and robustness of the material. We also used this AZO-CLCP/CNT nanocomposite as a microvalve membrane actuator, which can be controlled by light, for a conceptual device of a microfluidic system. The results showed that this AZO-CLCP/CNT nanocomposite may have great potential in smart actuator applications for biological engineering, medical treatment, environment detection and microelectromechanical systems (MEMS), etc.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Photo Actuation Performance of Nanotube Sheet Incorporated Azobenzene Crosslinked Liquid Crystalline Polymer Nanocomposite

Meng

Yu-chang

et al. 2019

Polymers

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“…While in LCEs phase transitions are directly responsible for shape changes due to the realignment of molecular groups throughout the material, in SMPs phase transitions cause the material to be fixed in or recover a programmed shape. Contributions to LCEs can be found, e.g., in [65,[119][120][121][122][123][124][125]. Such an effect has been extended to achieve a two-way triple SME in [126].…”

Section: Two-way Smpsmentioning

confidence: 99%

Two-Way and Multiple-Way Shape Memory Polymers for Soft Robotics: An Overview

2020

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Shape memory polymers (SMPs) are smart materials capable of changing their shapes in a predefined manner under a proper applied stimulus and have gained considerable interest in several application fields. Particularly, two-way and multiple-way SMPs offer unique opportunities to realize untethered soft robots with programmable morphology and/or properties, repeatable actuation, and advanced multi-functionalities. This review presents the recent progress of soft robots based on two-way and multiple-way thermo-responsive SMPs. All the building blocks important for the design of such robots, i.e., the base materials, manufacturing processes, working mechanisms, and modeling and simulation tools, are covered. Moreover, examples of real-world applications of soft robots and related actuators, challenges, and future directions are discussed.

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“…For reimparting the shape memory effect to the former, a new programming step has to be applied after recovery. So far, two-way SMPs are further classified as quasi two-way SMPs and true two-way SMPs, depending on whether they need an applied force to take effect − or not. − The true two-way SMPs include (i) crosslinked crystalline polymers, − (ii) liquid crystalline elastomers, − and (iii) laminated polymers (stacked layers of crosslinked crystalline polymers or crosslinked crystalline polymer/elastomer). − Relatively, crosslinked crystalline polymer-based two-way SMPs are easier to be made. As a substitute for the external stress, internal stress providers (including elastomeric networks, , higher T m crystalline phases, − rubbery domains, H-bonds,…”

Section: Introductionmentioning

confidence: 99%

Repeated Intrinsic Self-Healing of Wider Cracks in Polymer via Dynamic Reversible Covalent Bonding Molecularly Combined with a Two-Way Shape Memory Effect

Fan

Rong

Zhang

et al. 2018

ACS Appl. Mater. Interfaces

114

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To enable repeated intrinsic self-healing of wider cracks in polymers, a proof-of-concept approach is verified in the present work. It operates through two-way shape memory effect (SME)-aided intrinsic self-healing. Accordingly, a reversible C–ON bond is introduced into the main chain of crosslinked polyurethane (PU) containing an elastomeric dispersed phase (styrene–butadiene–styrene block copolymer, SBS). The PU/SBS blend was developed by the authors recently, and proved to possess an external stress-free two-way SME after programming. As a result, the thermal retractility offered by the SME coupled with the reversible C–ON bonds can be used for successive crack closure and remending based on synchronous fission/radical recombination of C–ON bonds. Moreover, multiwalled carbon nanotubes are incorporated to impart electrical conductivity to the insulating polymer. Repeated autonomic healing of wider cracks is thus achieved through narrowing of cracks followed by chemical rebonding under self-regulating Joule heating. No additional programming is needed after each healing event, which is superior to one-way SME-assisted self-healing. The outcomes set an example of integrating different stimuli-responsivities into single materials.

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Two-step crosslinked liquid-crystalline elastomer with reversible two-way shape memory characteristics

Cited by 18 publications

References 46 publications

Photo Actuation Performance of Nanotube Sheet Incorporated Azobenzene Crosslinked Liquid Crystalline Polymer Nanocomposite

Photo Actuation Performance of Nanotube Sheet Incorporated Azobenzene Crosslinked Liquid Crystalline Polymer Nanocomposite

Two-Way and Multiple-Way Shape Memory Polymers for Soft Robotics: An Overview

Repeated Intrinsic Self-Healing of Wider Cracks in Polymer via Dynamic Reversible Covalent Bonding Molecularly Combined with a Two-Way Shape Memory Effect

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