Synthesis and characterization of epoxidized styrene-butadiene block copolymers as templates for nanostructured thermosets

A wide range of epoxidized styrene-block-butadiene block copolymers were synthesized using hydrogen peroxide in the presence of an in situ prepared methyltrioctylammoniumtetrakis(diperoxotungstate)phosphate as the catalyst system in a water/dichloroethane biphasic system. H-1 NMR and FT-IR spectra revealed that the epoxidation procedure led mainly to 1,4-epoxidized butadiene units. GPC analysis showed that expoxidation changed the copolymer architecture into stars with fewer arms. The copolymers showed two glass transition temperatures in accordance with the phase separation for block copolymers and, as revealed in AFM images, the self-assembly takes place on a nanometer scale. Moreover, epoxidized styrene-butadiene (SB) copolymers showed improved miscibility with epoxy monomers leading to self-assembled nanostructures in the uncured state. This allows them to be used as templates for nanostructured resins.