Dependence of the interfacial reaction and morphology development on the functionality of the reactive precursors in reactive blending

PMMA containing 50 wt% of anthracene-labeled PMMA chains end-capped by a phthalic anhydride group (anth-PMMA-anh) has been melt blended at 180°C with PS containing 33 wt% of chains end-capped by an aliphatic primary amine (PS-NH₂) and PS bearing 3.5 pendant amine groups (as an average) along the chains (PS-co-PSNH₂), respectively. The reactive chains have been synthesized by atom transfer radical polymerization. Conversion of anth-PMMA-anh into PS-b-PMMA and PS-g-PMMA copolymers has been monitored by SEC with a UV detector. The interfacial reaction mainly occurs in the initial melting and softening stage (<1.0 min.), although at a rate which strongly depends on the number of reactive groups attached to PS chains, the higher conversion being observed for the PS-co-PSNH₂ containing blends. The phase morphology depends on the architecture of the in-situ formed copolymer. Indeed, a coarser phase dispersion is observed in case of the graft copolymer compared to the diblock.