Synthesis and characterization of poly[(methylsilylene ethynylenephenyleneethynylene)-co-(dimethylsilylene ethynylenephenyleneethynylene)]s

A series of poly[(methylsilylene ethynylenephenyleneethynylene)-co-(dimethylsilylene ethynylenephenyleneethynylene)] s were synthesized by the incorporation of various ratios of methylsilylene to dimethylsilylene units into the polymer chain backbone. The resultant copolymers were soluble in a variety of common organic solvents at room temperature. The copolymers were characterized by FT-IR, 1H-NMR, GPC, rheological analysis, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The results showed that the copolymers exhibited good processability and cured at low temperatures like 200°C. The curing reactions involved in hydrosilylation of Si-H and alkyne groups and the polymerization of alkynes. T d5 (5% weight loss) of the cured copolymers ranged from 629°C to 686°C, and the decomposition residues of cured copolymers at 1000°C ranged from 88.1% to 90.9% under nitrogen. Thermal stability of the copolymers increased with the introduction of methylsilylene units into polymer chains. The cured copolymers were sintered at 1450°C, and the results of X-ray diffraction analysis showed that β-SiC was formed in the sintered products.