Silane-functional benzoxazine: synthesis, polymerization kinetics and thermal stability

A benzoxazine with siloxane and phenyl sulfone units (BS-b) was synthesized by using aminopropyltriethoxysilane, 4,4'-dihydroxydiphenylsulfone and paraformaldehyde as precursors via Mannich condensation. Then the hydrolysis and polycondensation reactions of siloxane units were performed and benzoxazine bearing polysiloxanes (BS-PSO) were obtained. The ring-opening polymerization reactions of both BS-b and BS-PSO were studied by Fourier transform IR spectroscopy and DSC in non-isothermal conditions. The kinetics of the polymerization of BS-b were found to be well described by using an nth-order kinetic model for n = 0.7 (activation energy 141 kJ mol(-1)). The BS-PSO was also used to modify bisphenol-A-based benzoxazines (BA-a), and the morphological structure and thermal properties of the copolymer were investigated. The TGA results indicate that the silane-functional polybenzoxazines display enhanced initial decomposition temperature and char yields in comparison with poly(BA-a). These results are believed to be important for the development of new flame-retardant laminates. (C) 2017 Society of Chemical Industry.