The scaling coefficient α decreases significantly when the epoxy/PEI blend is filled with certain concentration of MEK–SiO2 nanoparticles, implying that the nanoparticles are forcing the coarsening mechanism towards the diffusion-controlled regime.

PS-b-PCL block copolymer is used to study its influence on the phase evolution of epoxy resin/polyetherimides (PEI) blends cured with methyl tetrahydrophthalic anhydride. The effect of PS-b-PCL on the reaction-induced phase separation of the thermosetting/thermoplastic blends is studied via optical microscopy, scanning electron microscope, and timeresolved light scattering. The results show that secondary phase separation and typical phase inverted morphologies are obtained in the epoxy/PEI blends with addition of PS-b-PCL. It can be attributed to the preferential location of the PS-b-PCL in the epoxy-rich phase, which enhances the viscoelastic effect of epoxy/PEI system and leads to a dynamic asymmetry system between PEI and epoxy. The PS-b-PCL block copolymer plays a critical role on the balance of the diffusion and geometrical growth of epoxy molecules.