REACTIONS ON VINYL ISOCYANATE MALEIMIDE COPOLYMERS - NLO-FUNCTIONALIZED POLYMERS WITH HIGH GLASS TRANSITIONS FOR NONLINEAR-OPTICAL APPLICATIONS/

A new reactive copolymer system with high, but still variable glass-tr ansition temperatures was synthesized. This was accomplished by copoly merizing various N-substituted maleimides with methylvinyl or vinyl is ocyanate, so that a polymer with a 1:1 composition of the two monomers is obtained. Further functionalization is then possible with any nucl eophile known from comparable low molecular weight reactions. With dif ferent substituents attached to the imide-ring, T-g can be adjusted be tween 120 and 210 degrees C. Two effects of the substituent at the imi de nitrogen are observed. Bulky groups reduce the mobility of the chai n and lead to high T-g values. A similar tendency is found for smaller , less flexible substituents. In this case, the inter-and intramolecul ar forces of hydrogen-bonding (urethanes) contribute to the effects fo r high T-g's. The potential of these copolymers was highlighted here f or NLO chromophores. A variety of different NLO chromophores was attac hed to the polymer backbone by reaction of a hydroxyalkyl-containing c hromophore with the isocyanate groups, thereby forming urethane linkag es between chromophore and polymer. The polymers functionalized in thi s way show nearly unchanged glass transition temperatures and offer th us the possibility to prepare NLO polymers with high T-g values and go od solubility. It is important that even base labile NLO chromophores and systems labile to radical conditions can be fixed easily. The adva ntage of this system is highlighted by the fixation of NLO chromophore s with tricyanovinyl (C2), tricyanochinodimethane (C3) and heterocycli c accepters (C4). With one of these systems a d(33) value of 53 pm/V c ould be obtained for a loading with only 12 wt % of chromophore.