Synthesis and characterization of carborane bisphenol resol phenolic resins with ultrahigh char yield

• Published in: Chinese journal of polymer science 2015-11, Vol.33 (11), p.1606-1617
• Main Authors: Qi, Shi-cheng, Han, Guo, Wang, Hong-rui, Li, Ning, Zhang, Xiao-a, Jiang, Sheng-ling, Lu, Ya-fei
• Format: Article
• Language: English
• Subjects: Bisphenols; Cage; Carborane; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Combustion; Condensed Matter Physics; Fourier transforms; Industrial Chemistry/Chemical Engineering; Infrared spectroscopy; Molecular weight; Phenolic resins; Polymer Sciences
• ISSN: 0256-7679; 1439-6203
• DOI: 10.1007/s10118-015-1712-1

Two carborane-containing resol phenolic resins (P 1 and P 2 ) 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 P 1 is mainly composed of hydroxymethylated o -carborane bisphenols, the M w of which was restrained around 500 due to the strong steric hindrance of o -carborane bisphenol. In contrast, the molecular weight of P 2 was well regulated under various reaction conditions. The obtained resins were characterized with spectroscopic techniques including FTIR, 1 H-NMR, 13 C-NMR, and 11 B-NMR, which gave satisfactory results. TGA studies show that P 2 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 B 2 O 3 at elevated temperatures, which postpones the thermal decomposition of phenolic resin and accounts for the high char yield.