Photomechanical response of polymer-dispersed liquid crystals/graphene oxide nanocomposites

Abstract

Recyclable, fast and visible-light responsive polymer-dispersed liquid crystal (PDLC)/graphene oxide (GO) nanocomposite films were successfully fabricated by a combination of solution casting and mechanical stretching. In the PDLC/GO nanocomposite films, one low-molecular-weight nematic LC (5CB) formed a separated phase and GO-dispersed polyvinyl alcohol (PVA) was used as the film matrix. Upon irradiation with visible light, PDLC/GO nanocomposite films showed photomechanical response, bending toward the light source along the stretching direction. Here, GO functioned as the light absorbent and nanoscale heat source to thermally induce a phase transition with 5CB from homogeneous alignment to an isotropic phase. Thus, volume contraction occurred on the surface area of the nanocomposite films due to the photothermal effect of GO, whereas little change took place in the opposite area, resulting in the visible light-induced photomechanical response in a bimetal-like mode. These PDLC/GO nanocomposite films can be potentially applied in soft actuators and micro-optomechanical systems with visible light as the energy source.