Hydrogen bond-containing oligomer as a facile interfacial mediator in rubber/silica composites

Silica is one of the most important reinforcements in the rubber industry due to its indispensable applications in green tires. However, the significant difference in polarity between conventional diene rubber and silica generally results in poor silica dispersion and, hence, considerably compromises the overall performance of the composites. Herein, a poly (hydroxyethyl methacrylate) oligomer was synthesized via living radical polymerization using disulfiram as an iniferter. Upon thermal activation, the oligomer can further divide into macroradicals that are capable of directly grafting onto the unsaturated moieties in the rubber skeleton. Therefore, the pendant ester and hydroxyl functionalities can interact with silanol groups on the silica surface through interfacial hydrogen bonding, which significantly improves the interfacial interaction and facilitates the dispersion of silica. Accordingly, incorporating a small amount of oligomer (less than 3.5 wt%) can achieve a remarkable improvement in the tensile modulus and rolling and wet skid resistances of the obtained composites. We envisage that the present reactive oligomer can provide an effective strategy toward in situ modification of the rubber skeleton, which also has significant potential to optimize the static and dynamic performance of rubber/silica composites for tire tread applications.