SEQUENCE DISTRIBUTION OF STYRENE-BUTADIENE COPOLYMERS BY OZONOLYSIS, HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC AND GAS-CHROMATOGRAPHIC MASS-SPECTROMETRIC TECHNIQUES

The sequence distribution of styrene units in various styrene-butadien e copolymers (SBR) was investigated by liquid chromatographic (LC) and gas chromatographic-mass spectrometric (GC-MS) measurements on their ozonolysis products. Ozonolysis was performed in methylene chloride fo llowed by reductive degradation with lithium aluminium hydride. LC was found to be a very effective technique for the characterization and q uantitative evaluation of the sequence distribution of random and tape red block copolymers because of its high detection efficiency of short and long sequences. LiChrospher C-18 reversed-phase columns, a ternar y gradient system and an evaporative light-scattering detector were us ed. Peaks corresponding to various low-molecular-mass species were ide ntified by GC-MS and assigned to 1,4Bde-(Sty)(m)-1,4Bde or 1,4Bde-(Sty )(m)-(1,2Bde)(n)-1,4Bde sequences of the original copolymers (Bde = bu tadiene, Sty = styrene).