Reinforcement of polychloroprene by grafted silica nanoparticles

Reversible addition-fragmentation chain transfer polymerization of chloroprene on the surface of silica nanoparticles was performed to obtain polychloroprene-grafted-silica nanoparticles (PCP-g-SiO2 NPs). These particles were dispersed in a commercial polychloroprene matrix to obtain PCP nanocomposites with different silica core loadings (1, 5, 10, and 25 wt%). Two different chain graft densities were studied (“low,” 0.022 ch/nm2 and “high,” 0.21 ch/nm2) as a function of the grafted polymer molecular mass. The cured samples showed significant improvement in the mechanical properties of the PCP rubber nanocomposites as compared to the unfilled PCP as measured by standard tensile and dynamic mechanical analysis even with low silica content. The mechanical properties of the nanocomposites were notably enhanced when the graft density was low and grafted molecular masses were high. Transmission electron microscopy (TEM) and Small-Angle X-ray Scattering (SAXS) were used to analyze the dispersion states of the grafted nanoparticles which confirmed the correlation between high grafted chain lengths and improved dispersion states and mechanical properties. [Display omitted] •Polychloroprene grafted nanoparticles were prepared with precise control of graft density, molar mass and dispersity.•Correlations were made between dispersion state in an industrial rubber andmechanical properties.•High molar mass grafts and low chain density provided the best dispersion and largest improvements in mechanical properties.