ABSTRACT:The copolymer of 1-chloro-1,3-butadiene (CB) and styrene (St) was synthesized and its composition and distribution in poly(CB-co-St) were investigated by thin-layer chromatography (TLC). The concentration gradient development method of a tetrahydrofuran-cyclohexane mixture was useful for separating the copolymer into its components. Resolution by molecular weight was not significant under the present conditions. The experimental results on the compositional distribution of poly(CB-co-St)s obtained at high conversion were in close agreement with the values calculated from the monomer reactivity ratios and conversion. Also, the composition of the copolymers having a CB content too small for ordinary elemental analysis to be applicable could be assayed by TLC. The observed CB content was below I mol%, and agreed well with that calculated.KEY WORDS 1-Chloro-1,3-butadiene Styrene CopolymerCompositional Distribution I Compositional Heterogeneity I Thin Layer Chromatography IThe preceding paper 1 in this series suggested that the characterization of poly(l-chloro-1 ,3-butadieneco-styrene) was important for understanding the polymer reactions of the copolymer. The bulk copolymerization of 1-chloro-1 ,3-butadiene (CB) with styrene (St) was carried out, and the monomer reactivity ratios and factors influencing the molecular weight of poly(CB-co-St) were discussed 1 in that paper. In the present study, the compositional distribution in poly(CB-co-St) is investigated by thin-layer chromatography (TLC). Copolymers are usually polydisperse not only in molecular weights but in chemical compositions; i.e., they show compositional heterogeneity. Data on the compositional distribution of poly(CB-co-St) may be useful for two reasons: the distribution can affect the reactivity of CB-St copolymer in polymer reactions where chlorine in CB unit is involved, and provides experimental proof for the theory of copolymerization kinetics (terminal model for CB-St).