Preparation of anisotropic films for liquid crystal display application

The photoinitated polymerization of 2-chloro-1, 4-phenylene bis[4-[6-(acryloyloxy)hexyloxy]benzoate](1M) and trans-1, 4-bis(4-(2-(2,3-epoxypropyloxy)-ethoxy)-phenyl)-cyclohexyldicarboxylate (3M) were studied. Both monomers exhibit a wide temperature range of nematic phase. The monomers were oriented in their nematic phase at a substrate having been coated with polyimide and unidirestionally rubbed with a nylon cloth. During polymerization, the ordering of the LC molecules was fixed, yielding a uniaxially crosslinked network. The clear LC networks exhibit a birefringence between 0.14 and 0.19, depending on the polymerization temperature. Finally, the nonmesogenic diluents, tetra(ethylene glycol) diacryalte and 1,2-bis(2,3-expoxypropyloxy)ethane were mixed with monomers 1M and 3M, subsequently decreasing the birefringences of the obtained LC networks. The LC networks containing non-mesogenic diluent exhibit not only a smaller birefringence but also a weaker birefringence dispersion in the visible region.