Synthesis and properties of a novel hyperbranched borate

The synthesis and properties of the high performance hyperbranched borate (HBb) was investigated by an A₂ to B₃ method under various monomer ratios of A₂ to B₃. 1,3-benzenediol, boric acid, and iron trichloride were dissolved in 60 mL of fresh distilled N-methyl-2-pyrrolidone (NMP) and 10 mL benzene in a 100 mL thoroughly dried, four-necked round-bottom flask equipped with an overhead stirrer, an Dean-stark trap connected with an condenser, a thermometer, and a nitrogen inlet and outlet. The system was slowly heated using an oil bath and reacted at 90°C for about 8 h under a dry nitrogen atmosphere until no more water was observed being collected in the Dean-stark trap. The phenolic resins with 10 wt % HBb exhibited both a higher temperatures of 456 C at 5% mass loss and a higher char residues of 75.4% at 800 C in nitrogen, which is superior to boron functional phenolic resins and comparable with ethynyl functional phenolic resins.