Synthesis of Polymer Having Thioxanthene Unit in Main Chain and Application to Photorefractive Composites

Poly (arylene ether) was successfully synthesized from 2,7-dichloro-9H-thioxanthen-9-one10,10-dioxide and bisphenol-A by a nucleophilic substitution reaction. The resulting polymer had a weight average molecular weight of 11,000 and exhibited a glass transition temperature of 184 degrees C. Photorefractive composites consisting of the synthesized polymer as an electron transporting component and electro-optically active 4- N,N-diethylamino-beta-nitrostyrene (DEANST) were prepared. A PR device with a thickness of 100 mu m was fabricated by sandwiching the PR composite between two indium-tin-oxide covered glasses. The electric field dependences of the gain coefficient and diffraction efficiency were investigated by two-beam coupling and four-wave mixing experiments, respectively. Compared with the composite with polyacrylate containing more electro accepting thioxanthene unit, the composite base on the synthesized polymer exhibited a higher diffraction efficiency and a larger net gain because of a weaker absorption although a slower response was observed.