Optical Properties of Fluorescent Polyimide Langmuir-Blodgett Films Containing 2,5-Distyrylpyrazine

UV-visible absorption and photoluminescence, originating from the 2,5-distyrylpyrazine (DSP) chromophore incorporated into the polymer backbone of polyamic acid and polyimide were demonstrated in the Langmuir-Blodgett (LB) films. The formation of an aggregated structure with a large Stokes shift and a weak emissive intensity was observed in the cases of the polyamic acid 1 and the polyimide 3 LB films. In-plane anisotropic optical properties manifested by the polymer LB films indicated that the DSP chromophores were highly oriented parallel to the dipping direction. Meanwhile, photo-polymerization of the DSP chromophores was observed in the polyimide 3 LB film. This suggested that a three dimensional network structure was formed in the polymer LB film.