Chrysin-Based Bio-Benzoxazine: A Copolymerizable Green Additive for Lowering Curing Temperatures and Improving Thermal Properties of Various Thermosetting Resins

Adding copolymerizable components into thermosetting resins is a common strategy to improve the thermal and mechanical properties of thermosets. However, it remains quite challenging to discover a universal copolymerizable additive that is applicable for various thermosetting systems. Here, the flexible molecular design of benzoxazine allows us to design a biobased benzoxazine monomer (CHR-ac) with several smart functionalities, which can copolymerize with various traditional thermosetting systems, including benzoxazine, epoxy, and bismaleimide resins. CHR-ac has been synthesized using paraformaldehyde, 3-aminophenylacetylene, and natural renewable chrysin as raw materials via the Mannich condensation. Specifically, the built-in intramolecular hydrogen bonding in CHR-ac results in a low polymerization temperature while it still maintains the advantage of long shelf life. In addition, the phenolic hydroxyl and acetylene groups in CHR-ac enable it to cross-link with well-commercialized thermosetting resins and significantly enhance their performance through the formation of highly cross-linked networks. Potentially, the rationally designed biobased benzoxazine in the current work can be used as a generic additive in thermosetting resins for applications spanning from the microelectronic to the aerospace industries.

Automated summary

Adding a smart biobased benzoxazine monomer to thermosetting resins can enhance their properties and can be used in various traditional thermosetting systems through copolymerization.