50.(スチレン-p-クロロスチレン)・2-ブロック共重合体の溶液物性 : 選択溶媒中での光散乱測定結果の異常性について

概要

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Conformational behaviors of a (styrene-p-chlorostyrene) di-block copolymer in cumene which is a good solvent for polystyrene but a θ solvent for poly-p-chlorostyrene, were studied over the temperature range of 55℃ to 25℃ by light scattering and osmotic pressure measurements. The block copolymer sample was prepared by anionic polymerization technique and its number average molecular weight and chlorostyrene content in weight fraction were 27.7×10^4 and 0.577, respectively. It was found that the Zimm plots obtained at 55℃ and 50℃ were normal but those obtained below 45℃ showed some anomalies which were more pronounced by lowering temperature. On the other hand, marked decrease in value of the osmotic second virial coefficient was observed below 35℃ and number average molecular weight measured at 30℃ was about 10% higher than that obatined at 40℃. The results reveal that multimolecular micelle formation due to intermolecular association takes place, at least partially, in these block copolymer solutions by lowering temperature. It was pointed out from study of gel permeation chromatograph of the block copolymer sample that dispersion of composition in the copolymer sample was rather small but a trace of high chlorostyrene content and high molecular weight species which was contained in the sample, has a critical effect on the formation of multi-molecular micelles in the block copolymer solutions.
東京女子大学の論文
1980-03-18