Silica/poly(styrene-alt-maleic anhydride) hybrid particles as a reactive toughener for epoxy resin

Amino-modified silica nanoparticles (SiO2NH2) were first prepared by hydrolytic condensation of tetraethyl orthosilicate and 3-aminopropylmethyldiethoxysilane. Then, organic-inorganic hybrid particles (SiO(2)SMA) were prepared by the amidation reaction between SiO2NH2 and poly(styrene-alt-maleic anhydride) (SMA). Subsequently, SiO(2)SMA particles were employed for modifying bisphenol-A epoxy/anhydride thermoset. Compared with pure cured epoxy, the modified epoxy thermosets with only 1 wt % of SiO(2)SMA particles could achieve a simultaneous toughening and reinforcing performance. The tensile strength, impact strength, and fracture toughness of epoxy thermoset were increased by 14.1, 44.3, and 114.4%, respectively. Moreover, the modification also improved the thermal stability of epoxy thermosets, and the modulus and glass transition temperature of cured resin were not sacrificed. It can be attributed to the rigid structure of SiO2, as well as the anhydride and carboxyl groups onto the surface of SiO(2)SMA particles participating in the epoxy curing reaction and effectively enhancing the crosslinking density of epoxy thermoset.