Wednesday, 13 October 2004 - 1:00 PM

This presentation is part of : Active Materials

Photonanomechanics of Liquid Crystal Elastomers (keynote lecture)

Martin Dunn, University of Colorado, University of Colorado, Department of Mechanical Engineering, Boulder, CO 80309

Liquid crystal elastomers exhibit unique, and somewhat unusual, properties that result from the combination of the properties of crosslinked elastomeric systems and liquid crystals. A particularly intriguing, and technologically-promising, feature is the ability to undergo large (100s of percent) shape changes upon illumination with light at a specific wavelength. In this talk we develop a multiscale constitutive theory to describe these photomechanical shape changes, and associated blocked stresses. The theory combines aspects of the molecular picture of anisotropic rubber elasticity with the nanomechanics of deformation that occur in certain molecular chains upon the absorption of photons. The model predicts experimentally observed anisotropic shape changes. The theory is further developed to model thin film systems where the photomechanical deformation is confined to a surface layer of the film, the thickness of which is a function of the depth profile for absorption of photons which depends on the wavelength of the light. Finally, using topology optimization techniques, we develop a design approach to yield shaped thin-film photomechanical structures.

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