Covalent Grafting Approach for Improving the Dispersion of Carbon Black in Styrene-Butadiene Rubber Composites by Copolymerizing p-(2,2′-Diphenylethyl)styrene with a Thermally Decomposed Triphenylethane Pendant

A facile approach for improving the dispersion of carbon black (CB) with a few functional groups in a rubber matrix was developed by preparing a new solution-polymerized styrene-butadiene-p-(2,2'-diphenylethyl)styrene (DPES) rubber (SBDR). The SBDR was shown to graft onto the surface of the CB through trapping a polymer radical formed by thermally dissociation of a triphenylethane pendant. The dispersion of CB in the rubber matrix was markedly improved by increasing the DPES content in SBDR, as demonstrated by transmission electron microscopy, small-angle X-ray scattering, and rubber process analysis. Furthermore, SBDR vulcanizates showed improved mechanical properties and good dynamic properties for tread rubber with increasing DPES content. This research provides a universal method for improving the dispersion of carbon materials containing few functional groups in polymer matrices.