A study on dopamine-assisted grafting of epoxidized elastomers for enhanced interfacial interaction in silica/ESBR composites

Abstract

In the tire industry, silica has gradually replaced carbon black as a filler. However, the surface of silica contains a large number of hydroxyl groups, leading to poor dispersion in rubber and weak interfacial interactions with the matrix. Surface grafting modification of silica can effectively improve interfacial bonding performance, but challenges such as difficult grafting and weak interfacial interactions persist. To address these issues, in this study the silica surface was first coated with polydopamine and then grafting modification was performed using epoxidized solution-polymerized styrene-butadiene rubber. In this work, a dual-interface sandwich model with different grafting densities was constructed using molecular dynamics simulations. By analyzing the interfacial interaction energy, mean-square displacement (MSD), diffusion coefficient and mechanical properties, the influence of grafting density on the interfacial performance of emulsion styrene-butadiene rubber (ESBR) composites was investigated. The results indicate that as the grafting density increases, the interfacial interaction energy and maximum stress first increase and then decrease, while the mean-square displacement and diffusion coefficient decrease. When the grafting density is 0.75 chains per nm², the interfacial binding energy and maximum tensile stress of the rubber composite reach their maximum values. Grafting density optimizes the dispersion of silica and interfacial compatibility by regulating the degree of interfacial mixing and steric hindrance effects. ESBR composites were prepared using wet mixing technology, and performance tests confirmed that the experimental results are consistent with the simulation results. This study provides a novel modification method and theoretical basis for addressing the weak interfacial bonding performance of silica in rubber.