A novel boron-silicon-alkynyl hybrid copolymer: Synthesis, characterization, heat resistance, and thermo-oxidative stabilities

摘要

A novel boron-silicon-alkynyl hybrid copolymer (BSD) was synthesized by condensation polymerization of 1,3-diethynylbenzene with dichloromethylsilane and boron trifluoride etherate. Fourier transform infrared and H-1-, C-13-, and Si-29-nuclear magnetic resonance spectroscopies were used to confirm the structures of the copolymers. Thermogravimetric analysis and differential scanning calorimetry showed that the polymer exhibited excellent heat resistance and thermo-oxidative stabilities under nitrogen and air. The cure cross-linking reaction mechanisms of the BSD were related to Diels-Alder intermolecular cyclization involving two C C bonds and hydrosilylation reaction between Si-H and C C bonds. The T-d5 of the BSD was above 591 degrees C and 530 degrees C under nitrogen and air, respectively. The residues at 1000 degrees C were above 88% under nitrogen and 25% in air. X-ray diffraction was used to study the formation of ceramics. The precursor for ceramics (beta-SiC, alpha-SiC, and B4C) was formed at 1600 degrees C under an argon atmosphere. The thermo-oxidative stabilities of the copolymers were attributed to the existing organic groups of alkynyl and inorganic elements of silicon and boron.