Insights into the preparation and performance of SiO2@graphene oxide/epoxidized solution-polymerized styrene butadiene rubber composites through experiments and molecular simulations

Epoxidized solution-polymerized styrene butadiene rubber (ESSBR) with different epoxidation degrees was prepared using formic acid as a catalyst. Experimental methods and density function theory calculation confirms that peroxyformic acid preferentially attacks trans-1,4-butadiene, and then cis-1,4-butadiene, and 1, 2-butadiene is not epoxidated due to high energy barrier. Two SiO 2 /graphene oxide hybrids covalently linked with bis-[3-(triethoxysilyl)propyl]-tetrasulfide or 3-aminopropyltriethoxysilane (KH550) were prepared and named SiO 2 @TESPT@GO and SiO 2 @KH550@GO, respectively. The results for ESSBR composites filled by hybrid fillers indicate that the increase of epoxy degree can greatly improve the wet skid resistance while maintaining rolling resistance. Besides, in the case of the same epoxy degree, the rolling resistance of composites using hybrid fillers is lower than that of using SiO 2 only. Notably, the SiO 2 @TESPT@GO/ESSBR composite with high epoxy degree (10.09%) has a good balance between wet skid resistance and low rolling resistance. Molecular dynamics simulation was further employed to perform fixed and cyclic stretching to give the mechanism for mechanical properties. Binding energy and mean square distance illustrate that that as the epoxy degree increases, on the one hand, the strong filler-matrix interactions will make the movement of ESSBR chains keep up with the strain. On the other hand, the strong filler-matrix and inter-chain interactions provide more friction. These two factors lead to an increase in hysteresis loss. Besides, only moderate filler-matrix interaction is conducive to the improvement of wet skid resistance, and too strong or too weak interaction is unfavorable.