SYNTHESIS AND PROPERTIES OF NOVEL THERMOSETTING POLYSILOXANE-BLOCK-POLYIMIDES WITH VINYL FUNCTIONALITY

A new class of vinyl-functionalized polysiloxane-block-polyimides were synthesized and characterized. The copolyimides were derived from 3,3 ',4,4'-benzophenonetetracarboxylic dianhydride (BTDA)/bis[4-(3-aminop henoxy)-phenyl]sulfone (BAPSM) combined with two kinds of vinyl-contai ning diaminopolysiloxanes and imidized by a solution method. They were highly soluble in various organic solvents. The vinyl groups of the c opolyimides were reacted with various hydrosilane compounds for crossl inking. The crosslinked products became insoluble in polar solvents an d were analysed and characterized by thermomechanical analysis (t.m.a. ), dynamic mechanical analysis (d.m.a.), and C-13 and Si-29 nuclear ma gnetic resonance (n.m.r.). The tensile modulus of the copolyimides hav ing a polysiloxane composition of 50 wt% increased approximately twofo ld after the crosslinking reaction, while that of the copolyimides wit h compositions of 10-30 wt% was similar to that of the original copoly imides. Their thermal expansion coefficient below the glass transition temperature (T-g), alpha 1, was nearly the same as that of the origin al copolyimides, while the coefficient above T-g, alpha 2, decreased d rastically compared with that of the original copolyimides. (C) 1998 E lsevier Science Ltd. All rights reserved.