Photoresponsive Surface Wrinkle Morphologies in Liquid Crystalline Polymer Films

Laminated bilayer films comprised of photoresponsive azobenzene-containing liquid crystalline polymer skin layers adhered on a thick elastomeric substrate were prepared, and the wrinkle formation upon uniaxial compression was investigated. Irradiation with UV light at 365 nm led to the disappearance of the wrinkle or reduction of wrinkle wavelength, depending on the content of azobenzene unit in the polymer. Such photoresponsive modulations of wrinkle formation could be well correlated with the photoinduced changes in the Young's modulus determined by indentation-retraction force curve measurements using an AFM cantilever. Additionally, the thickness modulation of the skin layer caused by the photoinduced mass migration can also be applied to modify the wrinkle wavelength. These photoresponsive surface wrinkle modulations are anticipated to offer new possibilities for the surface microfabrication technology.