Controlling the selective distribution of hydrophilic silica nanoparticles in polylactide/ethylene-co-vinyl-acetate blends via tailoring the OH surface concentration of silica

Abstract

In this short communication, we report a novel route to control the selective distribution of hydrophilic silica (SiO2) in polylactide/ethylene-co-vinyl-acetate (PLA/EVA) blends via tailoring the OH surface concentration of silica (often expressed as silanol number). Interestingly, SiO2 nanoparticles with low silanol number are mainly distributed in the EVA phase; those with medium silanol number are evenly dispersed in the EVA phase and between PLA and EVA phase; while those with high silanol number are primarily accumulated at the phase interface in the form of large agglomerates. The silanol number induced dispersion and distribution of SiO2 could be due to the regulated interactions between SiO2, EVA and PLA. Furthermore, the introduction of uniformly interfacial localized SiO2 imparts the blends a significantly improved impact toughness and well maintained strength and modulus. This work demonstrates that tuning the silanol number is a universal platform to manipulate the selective distribution of SiO2 toward a good stiffness-toughness balance in SiO2 filled immiscible polymer blends.