Synthesis of Poly{[bis(ethynylphenyl)silylene]phenylene}s with Highly Heat-Resistant Properties

Poly{bis[(trimethylsilylethynyl)phenyl]silylenephenylene}s ( 2a − d ) were prepared by the reactions of the respective poly[(diethoxysilylene)phenylene]s with (trimethylsilylethynyl)phenyllithium. Desilylation of the resulting polymers 2a − d with K 2 CO 3 /MeOH gave poly{[bis(ethynylphenyl)silylene]phenylene}s ( 3a − d ). Polymers 3a − d exhibit extremely high heat-resistance and their thermogravimetric analysis (TGA) in a nitrogen atmosphere shows the temperature of 5% weight loss ( T d 5 ) of 651−711 °C. Total weight loss at 1000 °C in TGA was determined to be 8−10% based on the initial weight. Thermal differential analysis (TDA) of the polymers reveals an exothermic peak around 220 °C probably due to cross-linking reactions concerning ethynyl groups. TGA of the polymers shows a high T d 5 of 436−566 °C even in air, although the total weight loss at 1000 °C was 76−81% of the initial weight, much higher than that in nitrogen.