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

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 M w 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, 1 H-NMR, 13 C-NMR, and 11 B-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 B 2 O 3 at elevated temperatures, which postpones the thermal decomposition of phenolic resin and accounts for the high char yield.

Synthesis and characterization of carborane‐containing polyester with excellent thermal and ultrahigh char yield

“…38,40 ANAL. Calcd for FTIR (m, cm 21 Synthesis of C,C 0 -1,7-Carboranyl-bis-Carboxylic Acid Chloride (4). 3 (220.2 mg, 0.949 mmol), PCl 5 (1680.2 mg) and 2 mL of POCl 3 were added into a three-neck flask equipped with a water condenser which connected to a drying tube and tail gas absorbed equipment and chlorine inlet below the surface of the liquid, then stirred for 2 h at 90 8C.…”

“…Owing to these distinctive properties, carboranes have been regarded as one of the most excellent organic groups to improve performance of organic polymers with remarkable thermal stability . Therefore, carboranes were incorporated into many traditional polymers to improve their thermal stability including epoxy resins, phenolic resins, polyurethanes, organic silicone polymers, benzoxazine resins, polyimides, and so forth.…”

“…ANAL. Calcd for FTIR (m, cm21 , KBr): 3047, 1314, and 654 (AOH), 2929 and 2869 (ACH 2 ), 2598 (B-H), 1707 (C @ O), 1431 and 738 (ACH 2 ), 1230 [C(O)O]. 1 H NMR (400 MHz, CDCl 3 ) d (ppm): 0.8-3.50 (10H, br m), 4.01 (2H, t), 2.46 (4H, t), 2.33 (4H, t).…”

Synthesis, characterization, and curing behavior of carborane‐containing benzoxazine resins with excellent thermal and thermo‐oxidative stability

“…Besides, the large volume of three‐dimensional cage endows carboranes with strong shielding effect on adjacent segments. Therefore, carboranes were incorporated into many traditional polymers to improve their thermal stability including polysiloxanes, epoxy resins, phenolic resins, aromatic polymers, etc. With the increasing appearance of new polymers, carboranes expanded their application fields such as dendrimers and conjugated polymers with light‐emission property …”

“…By virtue of the flexibility of molecular design, benzoxazine resins have been synthesized from various bisphenol, such as bisphenol A, bisphenol S, bisphenol AP, and bisphenol fluorenyl . We have successfully synthesized carborane bisphenols and corresponding carborane‐based epoxy resins and phenolic resins . Although carborane bisphenols have been proved to be excellent starting materials for many carborane‐containing polymers, to the best of our knowledge, they have not been utilized to synthesize benzoxazine polymers.…”