Anisotropic photo-polymerization and fluorescence study of discotic materials

The discotic films were prepared by coating the solution of liquid crystalline discotic monomer and initiator onto rubbed polyimide as alignment substrate. Liquid crystalline orientation in films was freezed-in by photo-polymerization (UV light) in nematic melt. Thickness and chemical constituents of polyimide was varied so as to obtain planar or homeotropic alignment. Photo-polymerization was studied with respect to isothermal DSC, PM, high temperature IR and solubility behavior of polymerized films. Further, the alignment of discotic films was studied by polarized fluorescence. Order parameter values were compared for planar, homeotropic and for films without any alignment substrate. Higher values were obtained for planar films formed on polyimide layer than formed solely on glass surface.