New high-performance thermosetting polymer matrix material systems

Abstract

The synthesis of amorphous, soluble triarylphosphine oxide-containing imide oligomers and arylene ether sulfone triarylphosphine oxide copolymers is described. The imide oligomers were controlled-molecular-weight systems endcapped with 3-phenylethynyl aniline. The arylene ether copolymers were synthesized in high molecular weight with controlled amounts of a novel comonomer, which contained pendent aryl amino groups that were subsequently functionalized with 4-phenylethynylphthalic anhydride. The phenylethynyl groups were employed to afford a higher curing temperature (380–420°C), which widens the processing window between T g and the cure temperature compared with the well studied ethynyl-endcapped systems. The polyimides were synthesized via solution imidization techniques, using the ester acid derived from various dianhydrides and several aromatic diamines. The ‘one-pot’ procedure utilized N-methylpyrrolidinone as the primary solvent and o-dichlorobenzene as the azeotroping agent, and reproducibly produced fully imidized soluble polyimides. Thermally cured polymers displayed good solvent resistance and exhibited glass transition temperatures comparable to their high-molecular-weight linear analogues. These polyimides also showed excellent thermal stability as judged by dynamic thermogravimetric analysis (t.g.a.). The arylene ether phosphine oxide copolymers were synthesized by a nucleophilic aromatic substitution reaction of the activated aryl dihalides with various bisphenolates. The thermally cured polyimides also exhibit excellent solvent resistance. Both the triarylphosphine oxide-containing polyimides and the arylene ether copolymers exhibited very high char yields as determined by t.g.a., e.g. the polyimides displayed about 50% char at 700°C in air.