The effect of surface modification on interfacial properties of polyisoprene/silica systems: an atomistic simulation study

Surface modification is an effective way to improve the dispersion of nanoparticles in polymer matrix, which is critical to the applications of polymer nanocomposites for enhanced mechanical, electrical, and thermal properties. Navigating the large parameter space available when designing commercial grade materials, is a formidable task that benefits from a fundamental understanding of polymer-surface interactions. In this work, we present an investigation of silane modification effects on polymer interfacial properties using atomistic simulations. Contrasting systems of amorphous silica substrates modified by two types of silane agents at two grafting densities to the bare substrate case, we show that silane grafting can effectively modulate chain configurations near the silica surface, including trains, loops, and tails, highlighting the individual effect of silane grafting density and chain length. We analyze the variation of polymer dynamics in adsorption, relaxation, and diffusion, and further demonstrate the correspondence with the distribution of train configuration. This detailed study offers detailed information of silane effects at microscopic level.