High-temperature elastomers from silarylene-siloxane-diacetylene linear polymers

The syntheses and characterization of linear silarylene-siloxane-diacetylene polymers 3a-c and their thermal conversion to crosslinked elastomeric materials 4a-c are discussed. Inclusion of the diacetylene unit required synthesis of an appropriate monomeric species. 1,4-Bis(dimethylaminodimethylsilyl)butadiyne [(CH3)(2)N-Si(CH3)(2)-C equivalent toC-C equivalent toC-(CH3)(2)Si-N(CH3)(2)] 2 was prepared from 1,4-dilithio-1,3-butadiyne and 2 equiv of dimethylaminodimethylchlorosilane. The linear polymers were prepared via polycondensation of 2 with a series of disilanol prepolymers. The low molecular weight silarylene-siloxane prepolymers la-c (terminated by hydroxyl groups) were synthesized via solution condensation of an excess amount of 1,4-bis(hydroxydimethylsilyl)benzene with bis(dimethylamino)dimethylsilane. The linear polymers were characterized by H-1 and C-13 NMR, Fourier transform infrared spectroscopy, gel permeation chromatography, thermogravimetric analysis (TGA), and DSC. The elastomers exhibited long-term oxidative stability up to 330 degreesC in air as determined by TGA. (C) 2001 John Wiley & Sons, Inc.