Amidation Way of Diphenolic Acid for Preparing Biopolybenzoxazine Resin with Outstanding Thermal Performance
Zizhao Qian, Yanglei Zheng, Qing Li, Lujie Wang, Feiya Fu, Xiangdong Liu
Abstract
Diphenolic acid (DPA) is a renewable chemical attracting great interest in biobased polymer science. Despite their low toxicity and high recyclability, the undesirable decarboxylation of DPA-based polymers generally leads to poor thermal stability and material failure restricting their practical applications. Here, we demonstrate that the incorporation of amide groups into a benzoxazine molecule can effectively avoid this problem while improving the thermally mechanical performance of the polybenzoxazine resin. We first synthesized a tetra-phenolic compound via a condensation reaction of DPA with hexanediamine through an ammonium salt route and then prepared a tetrafunctional benzoxazine, denominating as DHDA-fa, by a further reaction with furfurylamine and formaldehyde in a polyethylene glycol 200 (PEG-200) medium. The glass transition temperature (Tg) and decomposition temperature (Td5) of the resulting poly(DHDA-fa) were found to be 326 and 384 °C by DMA and TGA, respectively, which outperformed many biobased benzoxazine resins previously reported. Experimental results revealed that the enhanced hydrogen bonding and doubled oxazine functionary are the important contributors for the improved thermal and mechanical performances. This work confirmed a novel way to perfect DPA-based benzoxazine resins resulting in an effective strategy for developing biobased materials with high performance for practical applications.