In-situ observation of living anionic polymerization process by small-angle neutron scatterin

Miyamoto, Nobuyoshi; Tanaka, Hirokazu*; Yamauchi, Kazuhiro*; Hasegawa, Hirokazu*; Hashimoto, Takeji; Koizumi, Satoshi

The living anionic polymerization processes of polyisoprene, polystyrene, and polystyrene-block-polyisoprene were studied by in-situ small-angle neutron scattering (SANS) in combination with gel permeation chromatography and uv-visible spectroscopy. The polymerization reactions were carried out in benzene-d6 with sec-butyllithium as the initiator. The SANS intensity largely decreased upon termination of the living ends, indicating the presence of ionic aggregates during polymerization. The time-courses of the aggregation number f in the aggregates during the polymerizations were quantitatively estimated by analyzing the time-resolved SANS data on the basis of the model of star-polymer. In isoprene systems, the aggregation number decreased from ca. 10 to 4 with increasing molecular weight.