Effect of chemical structure of elastomer on filler dispersion and interactions in silica/solution-polymerized styrene butadiene rubber composites through molecular dynamics simulation

Abstract

The dynamic properties, filler–rubber interactions, and filler dispersion in silica/solution-polymerized styrene butadiene rubber (SSBR) composites with various chemical structures of SSBR were studied through molecular dynamics (MD) simulation. The structures of SSBR studied were non-modified, star-shaped, and in-chain modified by different contents of 3-mercaptopropionic acid. The mean square displacement (MSD), binding energy, glass transition temperature (T_g), and radial distribution function g(r) of filled SSBR models were investigated. We found that there was an optimum modifier content (14.2 wt%) at which the silica/SSBR composite had the lowest self-diffusion coefficient, the highest binding energy, and the best silica dispersion. The competing effects of hydrogen bonds, steric hindrance of 3-mercaptopropionic acid and rubber–rubber interactions led to the existence of this optimum modifier content of 14.2 wt%. Furthermore, the star-shaped SSBR as well as in-chain modified SSBR had strong interactions with the silica dispersed uniformly in the rubber matrix. The modeling results were in good agreement with our previous experimental results.