Liquid crystal elastomer–nanoparticle systems for actuation

Chambers, Martin; Finkelmann, Heino; Remškar, Maja; Sánchez‐Ferrer, Antoni; Zalar, Boštjan; Žumer, S.

doi:10.1039/b812423j

Cited by 100 publications

(83 citation statements)

References 43 publications

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“…This method also faces critical heat transfer problems. A thin layer of conducting carbon on the LCE surface has the same shortcoming, with loss of mechanical response [42][43][44][45][46].…”

Section: Open Accessmentioning

confidence: 99%

“…Studies of the electromechanical actuation of these materials have not yet been attempted. Since electromechanical actuation induced by a conducting layer due to Joule heating has been reviewed in [43], we here focus our attention on another mechanism, that is, the actuation due to electrostatic fields. Such actuation was demonstrated using mono-domain LCEs with CNTs [53].…”

Section: Electrical Actuationmentioning

confidence: 99%

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Nanoparticle-Liquid Crystalline Elastomer Composites

Marshall

Terentjev

2012

Polymers

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Liquid crystalline elastomers (LCEs) exhibit a number of remarkable physical effects, including a uniquely high-stroke reversible mechanical actuation triggered by external stimuli. Fundamentally, all such stimuli affect the degree of liquid crystalline order in the polymer chains cross-linked into an elastic network. Heat and the resulting thermal actuation act by promoting entropic disorder, as does the addition of solvents. Photo-isomerization is another mechanism of actuation, reducing the orientational order by diminishing the fraction of active rod-like mesogenic units, mostly studied for azobenzene derivatives incorporated into the LCE composition. Embedding nanoparticles provides a new, promising strategy to add functionality to LCEs and ultimately enhance their performance as sensors and actuators. The motivation for the combination of nanoparticles with LCEs is to provide better-controlled actuation stimuli, such as electric and magnetic fields, and broad-spectrum light, by selecting and configuring the appropriate nanoparticles in the LCE matrix. Here we give an overview of recent advances in this area with a focus on preparation, physical properties and actuation performance of the resultant nanocomposites.

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Section: Open Accessmentioning

confidence: 99%

Section: Electrical Actuationmentioning

confidence: 99%

Nanoparticle-Liquid Crystalline Elastomer Composites

Marshall

Terentjev

2012

Polymers

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“…With inclusion of carbon black (CB) nanoparticles, Chambers et al developed electrically conductive LCE/CB nanocomposites. [ 17 ] By passing electric currents, the temperature of LCE/CB can be increased to initiate the shape change. Similar approach was taken by Yang et al [ 18 ] and Kohlmeyer and Chen [ 19 ] to prepare LCE/SWCNT (single-walled carbon nanotubes) nanocomposites with very low SWCNT loading (0.1-0.2 wt%).…”

Section: Introductionmentioning

confidence: 99%

Reversible and Rapid Laser Actuation of Liquid Crystalline Elastomer Micropillars with Inclusion of Gold Nanoparticles

Liu

Wei

Hoang

et al. 2015

Adv Funct Materials

117

103

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It is highly desirable for liquid crystal elastomer (LCE) based microactuators to activate and actuate in a highly controlled fashion without perturbing the surrounding environment. To reach this goal, in this study, a novel experimental protocol is developed to successfully incorporate gold nanosphere (AuNS) and gold nanorod (AuNR) into polyacrylate based LCE elastomer to fabricate LCE/AuNR and LCE/AuNS micropillars or microactuators. The effect of gold nanoparticle inclusion has been studied by spectroscopy (UVvis-near-infrared), microscopy (transmission electron microscopy), thermal analysis (differential scanning calorimetry and thermogravimetric analysis), and x-ray scattering (wide-angle x-ray scattering and small-angle x-ray scattering). Finite element analysis is performed to examine the feasibility of utilizing the photothermal effect of AuNR/AuNS to enable photothermal actuation of LCE/AuNR and LCE/AuNS micropillars. The comparative experimental studies on the thermal and photothermal actuation behavior of the LCE, LCE/AuNS, and LCE/AuNR micropillar suggested that AuNR is an excellent candidate for developing high-performance LCE actuators with photothermal actuation capability. With inclusion of less than 1 wt% of AuNR, the very high maximum actuation strain (30%) and rapid response (a few seconds) have been achieved in LCE/AuNR micropillar actuators under 635 nm laser irradiation.

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“…1 This ability makes LCEs attractive candidates for a variety of applications in robotics, photonics, and microfluidics. It has been demonstrated that modified LCEs can exhibit thermal, 2-5 electrical, 6 and photo-induced 7,8 actuation; based on these achievements, a number of devices such as microvalves, 9 optical tweezers, and microgrippers 10 among others have been reported. Photo-induced actuation in particular is attractive because it can be triggered by an external "remote" stimulus (rather than by direct heating, which is inconvenient for most practical applications) and because the speed and periodicity of the stimulus can be finely controlled.…”

mentioning

confidence: 99%

Bending kinetics of a photo-actuating nematic elastomer cantilever

Torras

Zinoviev

Marshall

et al. 2011

Applied Physics Letters

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Liquid crystal elastomers (LCE) containing embedded carbon nanotubes (CNTs) contract when exposed to light, due to LC disordering induced by the ability of CNTs to absorb light and convert it into thermal energy. A cantilever made of LCE-CNTs exposed to light demonstrates dynamic bending due to inhomogeneous strain distribution caused by exponential heat generation across the cantilever width. Analysis of bending dynamics helps to extract parameters that are important for designing actuators based on these materials. In this work, we have carried out direct measurements of temperature evolution inside the cantilever and related its kinetics to the applied irradiation power.

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Liquid crystal elastomer–nanoparticle systems for actuation

Cited by 100 publications

References 43 publications

Nanoparticle-Liquid Crystalline Elastomer Composites

Nanoparticle-Liquid Crystalline Elastomer Composites

Reversible and Rapid Laser Actuation of Liquid Crystalline Elastomer Micropillars with Inclusion of Gold Nanoparticles

Bending kinetics of a photo-actuating nematic elastomer cantilever

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