Interfacial interaction modes construction of various functional SSBR-silica towards high filler dispersion and excellent composites performances

In this study, various interfacial interaction modes between silica and in-chain functionalized solution styrene butadiene rubbers (F-SSBRs) with -OH (3-mercaptopropanol, MPL), -COOH (11-mercaptoundecanoic acid, MUA), and -Si-(OCH2CH3)(3) (3-mercaptopropyltriethoxysilane, MPTES) were constructed at the molecular level. As the modes of interfacial interaction followed the order of single hydrogen bond interactions to dual hydrogen/covalent bond interactions to single covalent bond interactions, the interfacial interactions presented silica/SSBR-g-MPL < silica/SSBR-g-MUA < silica/SSBR-g-MPTES. Moreover, the interfacial interactions were enhanced as the grafting percentages of the functional group increased. The results showed that silica dispersion was enhanced upon improving the interfacial interaction. As the filler-rubber networks improved and filler-filler networks decreased, the dynamic mechanical properties of the silica/F-SSBR composites improved and were even superior to those of the silica/SSBR/bis(gamma-triethoxysilylpropyl)-tetrasulfide (Si69) composite. The rolling resistances of silica/SSBR-g-MPL, silica/SSBR-g-MUA, and silica/SSBR-g-MPTES composites decreased by 21.2%, 27.3%, and 50.8%, respectively. The wet skid resistances of silica/SSBR-g-MPL, silica/SSBR-g-MUA, and silica/SSBR-g-MPTES composites increased by 112.7%, 161.2%, and 184.3%, respectively. However, the excessively strong rubber-rubber networks led to poor mechanical properties. Filler-rubber, filler-filler, and rubber-rubber networks reached equilibrium in the silica/SSBR-g-MUA composite, which had excellent overall performances of high strength, low rolling resistance, and high wet skid resistance.