Preparation and properties of 1,2-polybutadiene grafting with poly(1,3-butadiene)-block-(dimethylsiloxane)

The development of silica-filling elastomers with high mechanical performance and good processability is still a great challenge. In this study, we fabricated siloxane-grafted atactic 1,2-polybutadiene (1,2-PB) rubber through grafting poly(1,3-butadiene)-block-(dimethylsiloxane) (PB-b-PDMS) onto 1,2-PB molecular chains by coordination polymerization using a molybdenum (Mo)-based catalyst system. The PB-b-PDMS with active double bonds was synthesized by anionic polymerization. Fourier transform infrared analysis (FTIR), elementary analysis, and GPC-MALLS-viscometer analyses verified the incorporation of PB-b-PDMS and the grafting structure in the resulting polymer. Scanning electron microscope (SEM), bound rubber testing, and dynamic mechanical analysis demonstrated that the graft-modification with PB-b-PDMS improved silica dispersity in the 1,2-PB matrix because the incorporation of siloxane groups provided stronger interfacial interaction with silica. Meanwhile, the graft-modified 1,2-PB exhibited lower Mooney viscosity, higher tensile strength, and lower heat build-up than unmodified 1,2-PB. This concept provides novel inspiration for the preparation of advanced rubber with promoted silica compatibility and mechanical performance.