Synthesis and property of end-functionalized poly(cis-1,4-butadiene) and its application to rubber compound

This article describes the successful quasi-living polymerization of 1,3-butadiene (BD) to high cis content butadiene rubber (HCBR) and the terminal functionalization of HCBR for application to rubber compound. A catalyst system based on neodymium carboxylate and organoaluminum compounds was prepared and employed to polymerize BD. Polymerization resulted in mostly proportional growth of molecular weight to the conversion while maintaining molecular weight distribution in relatively narrow range. The reactivity of chain end after the completion of polymerization was confirmed by comparing UV absorbance of polymers before and after the addition of chromophore compound to the unterminated polymerization mixture, as measured with size exclusion chromatography (SEC). A variety of functionalizing agents, which can provide end-groups of polymer with potential affinity to silica surface, was explored. Among them, compounds with epoxy, ketone, and ketimine groups produced polymers with clear evidences of functionalization. The HCBR functionalized with epoxy-containing alkoxysilane compound was tested in silica-filled rubber compound and showed remarkable improvement of silica dispersity as seen by change of viscoelastic responses. (c) 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47985.