Preparation, structure, and properties of end-functionalized miktoarms star-shaped polybutadiene-sn-poly(styrene-butadiene) rubber

Two miktoarm star-shaped rubbers with large-volume functional groups of 1,1-diphenylhexyl at the ends of arms (DMS-PB-SBR) and one miktoarm star-shaped rubber with n-butyl groups at the ends of arms (BMS-PB-SBR) were prepared by 1,1-diphenylhexyllithium (DPHLi) and n-butyl lithium as initiators, respectively. The molecular structures and morphological properties of the three rubbers (MS-PB-SBR) were studied and compared with those acquired from the blend consisting of star-shaped solution-polymerized butadiene styrene rubber (S-SSBR) and butadiene rubber (PBR) prepared by ourselves. The results showed that MS-PB-SBR exhibited a more uniform distribution of PBR phase and a smaller phase size of PBR than that of S-SSBR/PBR blend. It is found that MS-PB-SBR composites filled with CB showed the lower Payne effect than that of S-SSBR/PBR/CB composite, suggesting that the MS-PB-SBR/CB composite (particularly the DMS-PB-SBR/CB composites) would possess excellent mechanical properties, high wet-skid resistance, and low rolling resistance. For the studied MS-PB-SBR systems, the contribution of large-volume functional groups at the end of PBR molecular chains to decrease the rolling resistance was larger than that of Sn coupling effect. It is envisioned that the miktoarm star-shaped rubbers with 1,1-diphenylhexyl groups at the molecular ends would be useful for making treads of green tires. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014, 131, 40002.