Improvement of thermal resistance of polydimethylsiloxanes with polymethylmethoxysiloxane as crosslinker

Polymethylmethoxysiloxane (PMOS) with dense pendant Si-bound methoxy groups was synthesized by ring-opening polymerization and dehydrocoupling reaction. PMOS was incorporated with polydimethylsiloxane (PDMS) via hydrolytic condensation to prepare PMOS crosslinked polydimethylsiloxane. Highly crosslinked PMOS phases were in situ formed and the average crosslink density increased as the loading of PMOS went up. TG analysis results demonstrated that thermal decomposition process of PMOS crosslinked polydimethylsiloxane was divided into two stages, and the residual mass at 500 °C was 66 wt%. The pyrolysis reaction order was 0.974 and the activation energy for degradation was 78.0 kJ/mol. FTIR, XPS, XRD were performed to study the degradation residues. It was detected that dense PMOS phases could reduce the pyrolysis of polydimethylsiloxane at elevated temperature.