Nlo-Active Maleimide Copolymers With High Glass Transition Temperatures

We synthesized some novel rigid NLO-active maleimide copolymers bearing DR-1 moieties (PMPD, PHSD and PHND). All copolymers exhibited high T-g's (190similar to197degreesC), good solubilities for common solvents and excellent film-forming properties. Dependence of film thickness on the d(33) value for the poled copolymer films induced by corona poling was investigated and it was demonstrated that in less than thickness of 0.3 mum decrease of the thickness gives rise to remarkable increase in the d(33) value. The poled copolymer films exhibited large d(33) values (270 x 10(-9) esu (film thickness 0.13 mum) for PMPD, 290 x 10(-9) esu (0.12 mum) for PHSD and 350 x 10(-9) esu (0.08 mum) for PHND) as well as large r(33) values (51.0 pmV(-1) for PMPD and 60.4 pmV(-1) for PHND) which are significantly large compared to the value of LiNbO3 (31 pmV(-1)) as a typical EO material. The d(33) values of the poled copolymers were kept constant even after standing 1000h at 80degreesC, although a small decrease was observed at an initial stage. Further, the d(33) values did not change up to ca. 123degreesC upon heating at the rate of 10degreesC/min in all cases, Copyright (C) 2002 John Wiley Sons, Ltd.