SYNTHESIS AND CHARACTERIZATION OF TRIPHENYLPHOSPHINE OXIDE-CONTAININGPOLY(ARYL IMIDE)-POLY(DIMETHYL SILOXANE) RANDOMLY SEGMENTED COPOLYMERS

Poly(aryl imide)-poly(dimethyl siloxane) randomly segmented copolymers were synthesized by essentially a one-step solution imidization proce ss in a solvent system consisting of predominately o-dichlorobenzene w ith a small amount of n-methylpyrolidone. This solvent combination was selected because of its ability to afford homogeneous solutions throu ghout the polymerization process. This enabled copolymers of any desir ed poly(dimethyl siloxane) composition to be prepared. A hydrolyticall y stable triphenylphosphine oxide containing diamine, bis(3-amino-phen oxy-4'-phenyl) phenylphosphine oxide, was utilized as a chain extender and together with oxydiphthalic anhydride formed the hard segment in these copolymers. The soft segment was formed from alpha,omega-aminopr opyl poly(dimethyl siloxane) oligomers of controlled molecular weight. The presence of phosphorus and silicon contributes several unique pro perties to the system, including enhanced solubility, thermal stabilit y, and flame resistance. High molecular weight copolymers containing u p to 60% (w/w) of the poly(dimethyl siloxane) segments were successful ly prepared using this method. Gel permeation chromatography analysis, based on a universal calibration curve in CHCl3, was performed to det ermine the molecular weights and distribution. These copolymers with 4 0-60% (w/w) poly(dimethyl siloxane) exhibited upper T(g) values rangin g from 130 to 180-degrees-C and showed substantial char yields at 750- degrees-C in air, which increased with siloxane content. Dynamic mecha nical analysis confirmed the anticipated microphase behavior by the pr esence of two separate glass-transition regions. Both small angle x-ra y scattering and transmission electron microscopy measurements determi ned on well-characterized transparent cast films were used to better d emonstrate the multiphase nature of these copolymers.