Natural abundant resources and safe chemicals are attractive feedstocks for achieving circular sustainability. A wide variety of biophenols and greener amines offered interesting avenues in the evolution of the upcoming class of phenolic thermosets, polybenzoxazines (PBZ). High dependence on formalin as a starting material for monomer synthesis has prompted exploration of alternative safe chemicals. In this study, we designed a family of glyoxal-based benzoxazine (BZ) monomers to synthesize formaldehyde-free biothermosets, leveraging a proximity and promiscuity oxazine–oxazine dependent polymerization. The bi-oxazine functionality at the reactive C₂ center in the monomers demanded significantly low temperature for ring-opening polymerization with high polymerization enthalpy favoring an ease in polymer growth, overcoming challenges posed by earlier generation BZ monomers. Current work demonstrates the proof-of-concept for a highly efficient methodology for formaldehyde replacement in benzoxazine chemistry and holds promise for the exploration of a new platform chemical, glyoxal, toward the next generation of benzoxazine with unique reactivities.

中文翻译：

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乙二醛基双氧嗪苯并恶嗪：不含甲醛的生物热固性材料


自然资源丰富的资源和安全的化学品是实现循环可持续发展的有吸引力的原料。各种各样的生物酚和绿色胺为即将到来的酚类热固性材料聚苯并恶嗪 （PBZ） 的演变提供了有趣的途径。对福尔马林作为单体合成起始材料的高度依赖促使人们探索替代安全化学品。在这项研究中，我们设计了一系列基于乙二醛的苯并恶嗪 （BZ） 单体，利用邻近和混杂的恶嗪-恶嗪依赖性聚合来合成不含甲醛的生物热固性材料。单体中反应性 C₂ 中心的双恶嗪官能团需要非常低的温度才能进行开环聚合，具有高聚合焓，有利于聚合物的轻松生长，克服了上一代 BZ 单体带来的挑战。目前的工作证明了苯并恶嗪化学中甲醛替代的高效方法的概念验证，并有望探索一种新的平台化学品乙二醛，以开发具有独特反应性的下一代苯并恶嗪。