Micron-Sized Main-Chain Liquid Crystalline Elastomer Actuators with Ultralarge Amplitude Contractions

Yang, Hong; Buguin, Axel; Taulemesse, Jean-Marie; Kaneko, Kosuke; Méry, Stéphane; Bergeret, Anne; Keller, Patrick

doi:10.1021/ja905363f

Cited by 255 publications

(194 citation statements)

References 37 publications

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“…43 For example, LCE samples that were photo-cured at 400% strain demonstrated on average 115% actuation when heated and cooled between 22 and 90 °C and 207% actuation when heated and cooled between -25 and 120 °C. Compared to other LCE studies, Ahir et al 44 reported 400% actuation in LC polymer fibers and Yang et al 22 reported 300% to 400% actuation for micro LCE pillars. It is important to note that the present study measures actuation differently from much of the LCE literature, which often calculates strain based on the length of the sample in the isotropic state.…”

Section: Discussionmentioning

confidence: 89%

Synthesis of Programmable Main-chain Liquid-crystalline Elastomers Using a Two-stage Thiol-acrylate Reaction

Saed

Torbati

Nair

et al. 2016

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This study presents a novel two-stage thiol-acrylate Michael addition-photopolymerization (TAMAP) reaction to prepare main-chain liquidcrystalline elastomers (LCEs) with facile control over network structure and programming of an aligned monodomain. Tailored LCE networks were synthesized using routine mixing of commercially available starting materials and pouring monomer solutions into molds to cure. An initial polydomain LCE network is formed via a self-limiting thiol-acrylate Michael-addition reaction. Strain-to-failure and glass transition behavior were investigated as a function of crosslinking monomer, pentaerythritol tetrakis(3-mercaptopropionate) (PETMP). An example non-stoichiometric system of 15 mol% PETMP thiol groups and an excess of 15 mol% acrylate groups was used to demonstrate the robust nature of the material. The LCE formed an aligned and transparent monodomain when stretched, with a maximum failure strain over 600%. Stretched LCE samples were able to demonstrate both stress-driven thermal actuation when held under a constant bias stress or the shape-memory effect when stretched and unloaded. A permanently programmed monodomain was achieved via a second-stage photopolymerization reaction of the excess acrylate groups when the sample was in the stretched state. LCE samples were photo-cured and programmed at 100%, 200%, 300%, and 400% strain, with all samples demonstrating over 90% shape fixity when unloaded. The magnitude of total stress-free actuation increased from 35% to 115% with increased programming strain. Overall, the two-stage TAMAP methodology is presented as a powerful tool to prepare main-chain LCE systems and explore structure-property-performance relationships in these fascinating stimuli-sensitive materials.

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Section: Discussionmentioning

confidence: 89%

Synthesis of Programmable Main-chain Liquid-crystalline Elastomers Using a Two-stage Thiol-acrylate Reaction

Saed

Torbati

Nair

et al. 2016

JoVE

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“…The microscopic transition from the ordered but soft mesophase to the isotropic state can be triggered by temperature, light or electric fields 13 , and results in a directed macroscopic change of shape that can reach up to 400%, matching the performance of skeletal muscles 14,15 . Crucial to the preparation of LCEs is the uniform orientation of the anisotropic structural units, the so-called mesogens, along a common axis, the director.…”

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confidence: 99%

One-piece micropumps from liquid crystalline core-shell particles

et al. 2012

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Responsive polymers are low-cost, light weight and flexible, and thus an attractive class of materials for the integration into micromechanical and lab-on-chip systems. Triggered by external stimuli, liquid crystalline elastomers are able to perform mechanical motion and can be utilized as microactuators. Here we present the fabrication of one-piece micropumps from liquid crystalline core-shell elastomer particles via a microfluidic double-emulsion process, the continuous nature of which enables a low-cost and rapid production. The liquid crystalline elastomer shell contains a liquid core, which is reversibly pumped into and out of the particle by actuation of the liquid crystalline shell in a jellyfish-like motion. The liquid crystalline elastomer shells have the potential to be integrated into a microfluidic system as micropumps that do not require additional components, except passive channel connectors and a trigger for actuation. This renders elaborate and high-cost micromachining techniques, which are otherwise required for obtaining microstructures with pump function, unnecessary.

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“…First, the resolution can reach the submicron scale, and the structures are truly 3D 6 . Previously reported LCE micro fabrication methods, e.g., masked exposure 10 and replica molding 11 , provided resolution down to around 10 µm and only have 2D geometry. Secondly, DLW is a non-contact fabrication process.…”

Section: Introductionmentioning

confidence: 99%

Free-form Light Actuators — Fabrication and Control of Actuation in Microscopic Scale

Zeng

Wasylczyk

Parmeggiani

et al. 2016

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Liquid crystalline elastomers (LCEs) are smart materials capable of reversible shape-change in response to external stimuli, and have attracted researchers' attention in many fields. Most of the studies focused on macroscopic LCE structures (films, fibers) and their miniaturization is still in its infancy. Recently developed lithography techniques, e.g., mask exposure and replica molding, only allow for creating 2D structures on LCE thin films. Direct laser writing (DLW) opens access to truly 3D fabrication in the microscopic scale. However, controlling the actuation topology and dynamics at the same length scale remains a challenge.In this paper we report on a method to control the liquid crystal (LC) molecular alignment in the LCE microstructures of arbitrary threedimensional shape. This was made possible by a combination of direct laser writing for both the LCE structures as well as for micrograting patterns inducing local LC alignment. Several types of grating patterns were used to introduce different LC alignments, which can be subsequently patterned into the LCE structures. This protocol allows one to obtain LCE microstructures with engineered alignments able to perform multiple opto-mechanical actuation, thus being capable of multiple functionalities. Applications can be foreseen in the fields of tunable photonics, micro-robotics, lab-on-chip technology and others.

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Micron-Sized Main-Chain Liquid Crystalline Elastomer Actuators with Ultralarge Amplitude Contractions

Cited by 255 publications

References 37 publications

Synthesis of Programmable Main-chain Liquid-crystalline Elastomers Using a Two-stage Thiol-acrylate Reaction

Synthesis of Programmable Main-chain Liquid-crystalline Elastomers Using a Two-stage Thiol-acrylate Reaction

One-piece micropumps from liquid crystalline core-shell particles

Free-form Light Actuators — Fabrication and Control of Actuation in Microscopic Scale

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Micron-Sized Main-Chain Liquid Crystalline Elastomer Actuators with Ultralarge Amplitude Contractions

Cited by 255 publications

References 37 publications

Synthesis of Programmable Main-chain Liquid-crystalline Elastomers Using a Two-stage Thiol-acrylate Reaction

Synthesis of Programmable Main-chain Liquid-crystalline Elastomers Using a Two-stage Thiol-acrylate Reaction

One-piece micropumps from liquid crystalline core-shell particles

Free-form Light Actuators &#8212; Fabrication and Control of Actuation in Microscopic Scale

Contact Info

Product

Resources

About

Free-form Light Actuators — Fabrication and Control of Actuation in Microscopic Scale