Multiple roles of bound polymer chains in rubber reinforcement*

According to the Energy Technology Perspectives 2017, in 2050 the total number of cars globally will be three times greater than that in 2010. This increase implies that the development of advanced reinforced synthetic elastomers with balanced, superior performance is indispensable to meet the demand due to the dwindling availability of natural resources. To address this issue, we tackle the critical, but unsolved issue in the field: the roles of polymer chains bound to the filler surface in improving mechanical properties. Using a simplified carbon black-filled polybutadiene in conjunction with neutron scattering/spectroscopy techniques and molecular dynamics simulations, we reveal the novel hierarchical structures and dynamics of bound chains. We further demonstrate the mechanism behind the formation of a stable and adhesive polymer-filler interface between the bound chains and free chains in a matrix. The comprehensive understanding derived and validated with the model elastomer will be beneficial for many other polymer nanocomposites.