Sequence Distribution of Commercial SBR by Ozonolysis-GPC Measurement

Abstract Sequence distribution of commercially obtained styrene-butadiene copolymers (SBR) was investigated by high-resolution-GPC measurement of ozonolysis products. The ozonolysis-GPC of emulsion SBR samples showed peaks corresponding to 1 to 4 styrene sequences and styrene-1,2-butadiene sequences flanked by 1,4-butadiene units. In random SBR samples with anionic polymerization, long styrene sequences of from 8 to 19% were detected in addition to the short styrene sequences. So-called tapered-block structure was clearly observed in partially block SBR samples; a broad peak derived from block styrene sequences in a relative intensity of 49 to 55% was overlapped by peaks due to styrene sequences longer than 10 styrene units. The content of pure-block styrene sequences in S-B-S type triblock SBR samples was found to be 85 to 99% or above.