Formation of Thermosets via Molecular Pockets in Thermoplastic Chains: A Simple and Direct Way to Nanospherical Thermosets

By curing bisphenol A‐based benzoxazine in a thermoplastic polystyrene‐block‐poly (ethylene‐co‐1‐butene)‐block‐polystyrene (SEBS) block copolymer, nanospherical polybenzoxazines as small as 150 nm with narrow size distribution are obtained in high yield. This specific condition allows simple and direct formation of nano‐ or microspherical thermoset resins. A model of how the thermoplastic block copolymer chains act as a molecular pocket where the thermoset curing proceeds is presented. It is demonstrated that this mechanism requires (i) a particular block of thermoplastic copolymer which allows specific interaction with monomeric thermoset molecules, and (ii) the curing of thermosets in a molecular assembly structure to confine the phase separation of thermoset prepolymer during curing.