Highly Improved Thermal Properties of Hydroxyl-Containing Polymers via Modification by Benzoxazine Groups

Isocyanate functional benzoxazine (NCO‐4HBA‐a) is used for coupling with hydroxyl‐group‐containing molecules. Glycerol is used in a model reaction to study the urethane bonds formed between the NCO‐4HBA‐a and the glycerol's hydroxyl groups. The model supports a reaction between NCO‐4HBA‐a and poly(vinyl alcohol) (PVA), which leads to an improved char yield, determined by thermogravimetric analysis. Glycerol‐based benzoxazine is also an attractive benzoxazine synthesized from the products of biofuel production. Upon functionalization with benzoxazine and subsequent thermal treatment, the hydroxyl‐containing polymer gains thermal stability shown by improved char yield of polybenzoxazine cross‐linked PVA. Glycerol is used in a model reaction to study the urethane bonds formed between isocyanate functional benzoxazine (NCO‐4HBA‐a) and the hydroxyl groups of the glycerol. Upon functionalization with benzoxazine and subsequent thermal treatment, a hydroxyl‐containing polymer gains improved thermal stability, as reflected by its char yield in thermogravimetric analysis.