Bleaching and stimulated recovery of dyes and of photocantilevers

Corbett, Daniel; Warner, Mark

doi:10.1103/physreve.77.051710

Cited by 64 publications

(64 citation statements)

References 24 publications

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“…The light intensity is denoted by I. Here we ignored [8] the photo-induced cis → trans back-reaction [17] and also the effects of temperature change due to illumination. We look for the steady stateṅ t = 0, hence we find with I c = 1/Γτ .…”

Section: Light Induced Strainmentioning

confidence: 99%

Stress-free layers in photoinduced deformations of photoelastomer beams

Ábrahám

Károlyi

2015

International Journal of Non-Linear Mechanics

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Nematic liquid crystals combined with long molecular chains to form liquid crystal elastomers are capable of large extension. When such liquid crystal elastomers contain azo dyes to constitute photoelastomers, illumination can trigger large contraction. Beams made from such photoelastomers possess a non-uniform illumination and hence photostrain across their crosssection, resulting in bending and highly nonlinear stress distribution. Due to the nonlinear stress distribution, there can be more than one stress-free layers within the beam. In this paper, we present a dimensionless parametric study of nematic photoelastomer beams under the combined effects of light and mechanical loads. We show how the number of stress-free layers depends on three dimensionless parameters. The paths traced out by the system in the space of dimensionless parameters by varying the different real parameters are investigated, showing how the number of stress-free layers changes when e.g. the thickness or the mechanical load of the elastomer beam is varied. These results are important if the strain induced director rotation is not negligible.

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Section: Light Induced Strainmentioning

confidence: 99%

Stress-free layers in photoinduced deformations of photoelastomer beams

Ábrahám

Károlyi

2015

International Journal of Non-Linear Mechanics

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“…Under light illuminations, the photoisomerization process will decrease the phase transition temperature and the effective length ratio will be reduced. Assuming the light illumination is along the y-axis with y = 0 at the surface, because of the decay of the light due to absorptions, the effective length ratio at a depth y from the illuminating surface can be approximately calculated as [54,55] …”

Section: Light-induced Change Of the Effective Length Ratio And Effecmentioning

confidence: 99%

Effect of liquid crystal orientation on the quasi-soft opto-mechanical behavior of liquid crystal elastomers: constitutives and plane problems

et al. 2014

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Liquid-crystal elastomers (LCEs) are an exciting kind of smart material that can convert thermo-and opto-stimuli into mechanical actuations. In this paper, we formulate an opto-mechanical constitutive relation of soft LCEs for different director orientations, which shows that the soft material becomes transversally isotropic and quasi-soft under light illuminations and also the opto-strains are produced. We consider plane stress problems for simplification, with director variation through the depth of the beam-shaped LCEs. Detailed finite element simulations of two-dimensional free standing samples indicate that both the direction and the magnitude of the light-induced bending strongly depend on the orientation of the director and that the LCEs can behave completely soft under light illuminations at a critical orientation of the director, namely, the samples deform stress-freely in shear without bending. FE results show that large shear deformation is inevitably produced due to the rotation of the director, which means that the cross section plane will not remain normal to the middle line after deformation. And even some distortions may happen to cross sections, particularly when the orientation of LC is not parallel or perpendicular to the direction of light propagation.

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“…The magnitude or directionality of the photomechanical response of azo-LCN materials has repeatedly been controlled by the alignment of the linear polarization of the actinic source and the sample geometry [8,9,11,12,[14][15][16]. Theoreticians have found the unique blend of polymer physics, photochemistry, and mechanics a rich challenge [18,[20][21][22].…”

Section: Open Accessmentioning

confidence: 99%

Photomechanical Response of Composite Structures Built from Azobenzene Liquid Crystal Polymer Networks

Lee

White

2011

Polymers

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Abstract:Optically directed shape adaptive responses have been sought after for many decades in photoresponsive polymeric materials. A number of recent examinations have elucidated elucidated the unique opportunities of photomechanical responses realized in azobenzene-functionalized liquid crystalline polymer networks (both elastomers and glasses). This work summarizes and contrasts the photomechanical response of glassy polydomain, monodomain, and twisted nematic azo-LCN materials to blue-green irradiation. Building from this summary, the combinatorial photomechanical response observed upon irradiation of composite cantilevers is examined. Large scale shape adaptations are realized, with novel responses that may be of potential use in future employment of these materials in actuation.

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Bleaching and stimulated recovery of dyes and of photocantilevers

Cited by 64 publications

References 24 publications

Stress-free layers in photoinduced deformations of photoelastomer beams

Stress-free layers in photoinduced deformations of photoelastomer beams

Effect of liquid crystal orientation on the quasi-soft opto-mechanical behavior of liquid crystal elastomers: constitutives and plane problems

Photomechanical Response of Composite Structures Built from Azobenzene Liquid Crystal Polymer Networks

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