Nanostructured thermosetting blends of phenolic thermosets and poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) triblock copolymer

The amphiphilic triblock copolymer, poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (PEO-b-PPO-b-PEO) was incorporated into novolac resin to prepare thermosetting blends. The morphology of the thermosetting blends was investigated by means of atomic force microscopy (AFM) and small-angle x-ray scattering (SAXS) and the nanostructures were obtained. It was identified that the reaction-induced phase separation occurred in the blends of phenolic thermosets with the model poly(propylene oxide) (PPO), whereas poly(ethylene oxide) (PEO) was miscible with novolac resin after and before the curing reaction. In terms of miscibility and phase behavior of the subchains of the triblock copolymer with novolac resin, it was demonstrated that the formation of nanostructures in the thermosets followed a mechanism of reaction-induced microphase separation.