Preparation of heat resistant boron-containing phenyl silicone oil and its initial degradation mechanism in air

Boron-containing phenyl silicone oil (BCPSO) with terminal boronic hydroxyl groups was synthesized by acid-catalyzed balance condensation polymerization using phenylboric acid, dimethyldichlorosilane and diphenyldichlorosilane as raw materials. The structure of BCPSO was characterized by 1H, 13C and 29Si nuclear magnetic resonance (NMR) and Fourier transform infrared spectrometry (FTIR). The thermal degradation behavior of BCPSO was tested by thermogravimetry-Fourier transform infrared spectrometry (TG-FTIR) analysis. The TG-FTIR results indicated that thermal decomposition of BCPSO had significant hysteresis over that of phenyl silicone oil. The empty electron orbital of boron atom could accept electron of peroxide free radical to generate conjugation effect at initial degradation stage of BCPSO, and this phenomenon was confirmed by 11B NMR, FTIR and Raman spectroscopies. As a result, temporarily stable intermediate was formed which increased the heat resistant of BCPSO.