Toughening of epoxy thermosets with polystyrene‐block‐polybutadiene‐block‐ polystyrene triblock copolymer via formation of nanostructures

Abstract

In this contribution, we reported to utilize polystyrene‐block‐polybutadiene‐block‐polystyrene (PS‐b‐PB‐b‐PS), a commercial triblock copolymer to toughen epoxy thermosets. First, a PS‐b‐PB‐b‐PS triblock copolymer was chemically modified with hydroboration‐oxidation reaction, with which the midblock was hydroxylated whereas the endblocks remained unaffected. It was found that the degree of hydroxylation was well controlled. One of the hydroxylated PS‐b‐PB‐b‐PS samples was then used as the macromolecular initiator to synthesize a poly(ε‐caprolactone)‐grafted PS‐b‐PB‐b‐PS via the ring‐opening polymerization. It was found that the PS‐b‐PB‐b‐PS with poly(ε‐caprolactone) grafts can be successfully employed to nanostructure epoxy thermosets; the “core‐shell” microdomains composed of PB and PS were generated in the nanostructured thermosets. The nanostructured thermosets displayed improved fracture toughness. POLYM. ENG. SCI., 59:2387–2396, 2019. © 2019 Society of Plastics Engineers