Recent Advances in 4D Printing of Liquid Crystal Elastomers

Advanced Materials, Journal Year: 2022, Volume and Issue: 35(23)

Published: Dec. 3, 2022

Liquid crystal elastomers (LCEs) are renowned for their large, reversible, and anisotropic shape change in response to various external stimuli due lightly cross-linked polymer networks with an oriented mesogen direction, thus showing great potential applications robotics, bio-medics, electronics, optics, energy. To fully take advantage of the stimuli-responsive behaviors LCEs, it is preferable achieve a locally controlled alignment into monodomain orientations. In recent years, application 4D printing LCEs opens new doors simultaneously programming 3D geometry, offering more opportunities higher feasibility fabrication 4D-printed LCE objects desirable properties. Here, state-of-the-art advances reviewed, emphasis on both mechanisms applications. First, fundamental properties working principles representative techniques briefly introduced. Then, by advantages over conventional manufacturing methods demonstrated. Finally, perspectives current challenges development trends toward discussed, which may shed light future research directions this field.

Language: Английский

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Active Textile Fabrics from Weaving Liquid Crystalline Elastomer Filaments

Advanced Materials, Journal Year: 2023, Volume and Issue: 35(14)

Published: Jan. 14, 2023

Active fabrics, responding autonomously to environmental changes, are the "Holy Grail" of development smart textiles. Liquid crystal elastomers (LCEs) promise be base materials for large-stroke reversible actuation. The mechanical behavior LCEs matches almost exactly human muscle. Yet, it has not been possible produce filaments from that will suitable standard textile production methods, such as weaving. Based on recent LCE fibers, here, crafting active fabrics incorporating yarn, woven a loom, giving control over weave density and structure, is presented. Two types yarns (soft stiff) their incorporation into several weaving patterns tested, "champions" identified: twill pattern with stiffer yarn shows greatest blocking force 1-2 N cm-1 , weft rib 10% actuation strain repeated heating cycles. Reversible 3D shape changes fabric utilize circular lead cone shapes upon heating. seamless combination rich portfolio existing passive can transformative in creating new stimuli-responsive actuating

Language: Английский

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4D Printing for Biomedical Applications

Advanced Materials, Journal Year: 2024, Volume and Issue: 36(31)

Published: April 5, 2024

Abstract 4D (bio‐)printing endows 3D printed (bio‐)materials with multiple functionalities and dynamic properties. materials have been recently used in biomedical engineering for the design fabrication of devices, such as stents, occluders, microneedles, smart 3D‐cell engineered microenvironments, drug delivery systems, wound closures, implantable medical devices. However, success printing relies on rational objects, selection materials, availability appropriate types external (multi‐)stimuli. Here, this work first highlights different stimuli, strategies (bio‐)printing. Then, it presents a critical review applications discusses future directions research exciting area, including vivo tissue regeneration studies, implementation reversible shape memory behaviors, creation fast shape‐transformation responses, ability to operate at microscale, untethered activation control, application (machine learning‐based) modeling approaches predict structure–property design–shape transformation relationships (bio)printed constructs.

Language: Английский

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Modeling of a light-fueled self-paddling boat with a liquid crystal elastomer-based motor

Physical review. E, Journal Year: 2024, Volume and Issue: 109(4)

Published: April 29, 2024

Active materials possess unique properties of being able to respond autonomously external stimuli, yet realizing and regulating the motion behavior active machines remains a major challenge. Conventional control approaches, including sensor device control, are both complex difficult implement. In contrast, materials--based self-oscillators offer distinct such as periodic ease regulation. Inspired by paddle boats, we have proposed conceptual light-fueled self-paddling boat with photothermally responsive liquid crystal elastomer (LCE)--based motor that operates under steady illumination incorporates an LCE fiber. Based on well-established dynamic model rotation dynamics, equations for governing LCE-steered derived, driving torque LCE-based paddling velocity formulated successively. The numerical results show two modes illumination: static mode mode. regime arises from competition between frictional torque. Moreover, critical conditions required trigger quantitatively examined well significant system parameters affecting torque, angular velocity, velocity. exhibits benefits customizable size untethered ambient powered, which provides valuable insights into design application micromachines, soft robotics, energy harvesters, beyond.

Language: Английский

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Shape programming of liquid crystal elastomers

Communications Chemistry, Journal Year: 2024, Volume and Issue: 7(1)

Published: March 14, 2024

Liquid crystal elastomers (LCEs) are shape-morphing materials that demonstrate reversible actuation when exposed to external stimuli, such as light or heat. The actuation's complexity depends heavily on the instilled liquid alignment, programmed into material using various shape-programming processes. As an unavoidable part of LCE synthesis, these also introduce geometrical and output restrictions dictate final applicability. Considering LCE's future implementation in real-life applications, it is reasonable explore limiting factors. This review offers a brief overview current methods relation challenges employing LCEs soft, shape-memory components devices.

Language: Английский

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Smart chiral liquid crystal elastomers: Design, properties and application

Smart Molecules, Journal Year: 2024, Volume and Issue: 2(1)

Published: Feb. 29, 2024

Abstract Smart chiral liquid crystal elastomers are a class of soft photonic crystals with periodic nanostructures. There two kinds structural colors: cholesteric one‐dimensional helical nanostructure and blue‐phase three‐dimensional nanostructure. The self‐assembled can be dynamically controlled under external stimulation, the reflected color adjusted throughout visible light range. Along development innovative material systems cutting‐edge manufacturing technologies, researchers have proposed diverse strategies to design synthesize thoroughly investigated their properties potential applications. Here, we provide systematic review progress in fabrication smart elastomers, focusing on via surface‐enforced alignment, bar coating, 3D printing, anisotropic deswelling methods as well self‐assembly without additional alignment. able respond quickly stimuli wide range applications areas such adaptive optics, color‐changing camouflage, robotics, information encryption. This concludes perspective opportunities challenges for future elastomers.

Language: Английский

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Liquid Crystal Elastomer Twist Fibers toward Rotating Microengines

Advanced Materials, Journal Year: 2021, Volume and Issue: 34(9)

Published: Dec. 22, 2021

Untethered twist fibers do not require end-anchoring structures to hold their orientation and offer simple designs convenient operation. The reversible responsiveness of these allows them generate torque rotational deformation continuously upon the application external stimuli. therefore have potential in rotating microengines. In practical applications, high are desirable meet work capacity requirements. However, simultaneous endowment performance untethered remains a challenge. this study, liquid crystal elastomer fiber (LCETF) is designed developed with fixed twisting alignment mesogens provide responsiveness. Outstanding can be achieved when mesogenic disrupted through heat triggering. Owing significant intrinsic contractile ratio LCE material, LCETF reach 243.6° mm-1 . More importantly, specific 10.1 N m kg-1 , which exceeds previously reported values. addition, exploited microengine convert into electricity an induction voltage as 9.4 V. This broadens applications LCEs for energy harvesters, micromachines, soft robots.

Language: Английский

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Robust and Reprocessable Artificial Muscles Based on Liquid Crystal Elastomers with Dynamic Thiourea Bonds

Advanced Functional Materials, Journal Year: 2021, Volume and Issue: 32(13)

Published: Nov. 14, 2021

Abstract This work reports a new class of liquid crystal elastomers (LCEs) cross‐linked with poly(ether‐thiourea) comprising triethylene glycol spacer (LCE‐TUEG) wherein thiourea bonds impart hydrogen bonding capability as well permit dynamic covalent bond (DCB) exchange at elevated temperatures. While enhances the mechanical properties LCE‐TUEG, DCB allows macromolecular network rearrangement LCEs, resulting in various useful that are not present conventional including ability to undergo welding, melt and solution reprocessing, reprogrammable actuation, self‐healing. By exploiting these features, electrically powered artificial muscles fabricated can be actuated by Joule heating using resistive wire. In particular, an excellent specific is demonstrated (≈65 J kg −1 ) for muscle, full recyclability both LCE matrix metallic wire achieved. Furthermore, biomimetic hand created welding assembling multiple LCE‐TUEG films embedded wires, followed alignment. The integration microcontroller enables selective actuation each finger, gestures successfully demonstrated.

Language: Английский

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Intrinsic carbon nanotube liquid crystalline elastomer photoactuators for high-definition biomechanics

Materials Horizons, Journal Year: 2022, Volume and Issue: 9(3), P. 1045 - 1056

Published: Jan. 1, 2022

A facile strategy was proposed to prepare intrinsically-photoresponsive elastomer that simultaneously exhibited excellent mechanical toughness, stability and photoresponse. Some high-definition biomechanical applications were successfully demonstrated.

Language: Английский

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Liquid metal polymer composites: from printed stretchable circuits to soft actuators

Flexible and Printed Electronics, Journal Year: 2022, Volume and Issue: 7(1), P. 013002 - 013002

Published: Feb. 2, 2022

Abstract Soft polymers embedded with liquid metals like eutectic gallium-indium (EGaIn) exhibit unique combinations of mechanical, electrical, and thermal properties that are not possible other material systems. For example, a soft silicone elastomer percolating network EGaIn microdroplets can function as highly elastic conductor be stretched to 600% strain without significant change in electrical resistance. Depending on the choice polymer matrix microstructure, these composites engineered mechanical self-healing well high fracture toughness resistance tearing. Moreover, when solid filler particles silver flakes added EGaIn-polymer composites, they printable conductive inks fully elastic, non-marking, non-smearing cured. In this short review, we present different classes discuss approaches materials synthesis patterning, compare their Additionally, will review applications emerging class domains ranging from wearable bioelectronics robotics, shape programmable smart materials, energy storage harvesting devices.

Language: Английский

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