Optical alignment and fixation of liquid crystals using azopolymer networks

Anisotropic gels of a nematic liquid crystal (NLC) were prepared using opti cal alignment and fixation in the absence of surface orientation layers. Th e method consists of first making a homogeneous mixture that contains a rea ctive diacrylate monomer bearing azobenzene group, a nonreactive NLC and a photoinitiator, then irradiating the mixture by a laser at lambda=532 nm fo r the liquid crystal (LC) orientation induction. Subsequently, the mixture is exposed by a second laser at lambda=350 nm for photopolymerization givin g rise to anisotropic azobenzene network. Infrared dichroism measurements s how that a remnant long-range LC orientation is retained by the network. (C ) 2000 American Institute of Physics. [S0003-6951(00)04843-9].