Improving the toughness of epoxy with a reactive tetrablock copolymer containing maleic anhydride

Reactive block copolymers (BCPs) provide a unique means for toughening epoxy thermosets because covalent linkages provide opportunities for greater improvement in the fracture toughness ( K IC ). In this study, a tailored reactive tetrablock copolymer, poly[styrene‐ alt ‐(maleic anhydride)]‐ block ‐polystyrene‐ block ‐poly( n ‐butyl acrylate)‐ block ‐polystyrene, was incorporated into a diglycidyl ether of bisphenol A based epoxy resin. The results demonstrate the advantage of reactive BCP in finely tuning and controlling the structure of epoxy blends, even with 95 wt % epoxy‐immiscible triblocks. The size of the dispersed phase was efficiently reduced to submicrometer level. The mechanical properties, such as K IC , of these cured blends were investigated. The addition of 10 wt % reactive BCP into the epoxy resins led to considerable improvements in the toughness, imparting nearly a 70% increase in K IC . The designed reactive tetrablock copolymer opened good prospects because of its potential novel applications in toughening modification of engineering polymer composites.