Interface Engineering toward Promoting Silanization by Ionic Liquid for High-Performance Rubber/Silica Composites

In silica-filled rubber composites, the silanization modification of silica plays a vital role in enhancing the compatibility between silica and a rubber matrix and hence the properties of the composites. In the present study, with the goal of promoting silanization reactivity and extent, we utilize a phosphonium ionic liquid (PIL) as a novel catalyst for the silanization reaction between silica and bis(3-triethoxysilylpropyl)-tetrasulfide (TESPT), a commonly used silane in the tire industry, in the styrene–butadiene rubber (SBR) matrix. Dynamic rheological measurement, bound rubber measurement, freezing point depression, and heat capacity increment together show that the addition of a small amount of PIL into a TESPT-modified SBR/silica composite gives rise to significant improvement in the interfacial adhesion between silica and the rubber matrix, which is on account of the promoted silanization extent of silica with the catalyst of PIL. Consequently, the resulting composite prepared at room temperature with fewer parts of TESPT exhibits superior overall performance in comparison with the composites prepared by adding excessive TESPT and compounding at an elevated temperature. In particular, the energy loss during rolling of the rubber wheel is drastically decreased as a result of the improved interfacial silanization, which shows great potential in energy-saving green tires.