Tin‐coupled star‐shaped block copolymer of styrene and butadiene (I) synthesis and characterization

Abstract

AbstractA new kind of star‐shaped block copolymer: tin‐coupled polybutadiene‐b‐ploy(styrene‐butadiene) ((SB‐B)4Sn) was synthesized by two‐stage anionic polymerization technology. A novel multifunctional organo‐lithium was used as initiator, and two different types of copolymers were formed, namely, S‐PB‐PSB and S‐PB‐PSB‐PS, depending on the styrene content in loading solution (St%). In copolymerization, the homo‐polybutadiene block was formed in the first reaction stage, and the residual blocks were formed in the second stage with the presence of tetrahydrofuran (THF). S‐PB‐PSB was synthesized when the St% was lower than 34.9%, otherwise S‐PB‐PSB‐PS was generated. Nuclear magnetic resonance (NMR) results showed that the amount of vinyl based upon the butadiene content within poly(butadiene‐styrene) blocks decreased dramatically as the St% was increased. Dynamic mechanical thermal analyzer (DMTA) spectra showed broadened loss peak as the St% was increased. Transmission electron microscopy (TEM) was employed to characterize the copolymer morphology, and the results showed different phase‐separated morphologies as St% increased. Mechanical property testing results indicated that these two copolymers met the requirements of high performance tire tread. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008