Chinese Journal of Polymer Science, 2015, 33(11): 1606-1617.

Shi-cheng Qi, Guo Han, Hong-rui Wang, Ning Li, Xiao-a Zhang*, Sheng-ling Jiang and Ya-fei Lu.

Abstract

Two carborane-containing resol phenolic resins (P1 and P2) with high boron content were synthesized via the reaction of carborane bisphenols (1 and 2) with formaldehyde in the presence of alkaline. HRMS results indicate that P1 is mainly composed of hydroxymethylated o-carborane bisphenols, the Mw of which was restrained around 500 due to the strong steric hindrance of o-carborane bisphenol. In contrast, the molecular weight of P2 was well regulated under various reaction conditions. The obtained resins were characterized with spectroscopic techniques including FTIR, ¹H-NMR, ¹³C-NMR, and ¹¹B-NMR, which gave satisfactory results. TGA studies show that P2 shows char yield of 88.9% and 92.9% at 900 °C under nitrogen and air respectively. The imported carborane cage endows phenolic resin with ultrahigh char yield. Particularly, the char yield of the obtained carborane-containing phenolic resin under air is higher than that under nitrogen. FTIR and XRD confirm that the carborane cage could react with oxygen to form B₂O₃ at elevated temperatures, which postpones the thermal decomposition of phenolic resin and accounts for the high char yield