Halogen- and phosphorus-free allyl bisphenol A epoxy resins with low flammability

There are many concerns associated with high-valued applications of bisphenol A, especially for health and safety issues. Since its widespread use in epoxy resins, related functionalization upgrading has garnered a lot of attention. In particular, its high flammability poses a major risk to property and human safety. To reduce flammability, epoxy monomers, such as 2,2′-(((propane-2,2-diylbis(2-allyl-4,1-phenylene))bis (oxy))bis(methylene))bis(oxirane)(DBAQ) and 2,2′-(((propane-2, 2-diylbis(2, 6-diallyl-4, 1- phenylene))bis(oxy))bis(methylene))bis(oxirane)(DBAW) containing multiple allyls and epoxides have been fabricated and then cured using aromatic amines via a solvent-free process. Therein, structural modification was achieved via a concurrent ring-opening polymerization/olefin polymerization. All these networks displayed good mechanical properties and outstanding thermal stability. Most importantly, all thermosets exhibited excellent flame retardancy displaying a UL-94-V0 rating for combustion. Thus, a green protocol has been established for the generation of halogen- and phosphorus-free functional epoxy resins. It is believed that this approach may provide strong potential for sustainability in practical applications.