118.単分散性ポリ(p-メトキシスチレン)の合成およびその非摂動鎖長の測定

概要

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Five samples of poly (p-methoxystyrene) (PMeOSt) having narrow-molecular weight-distribution were prepared by anionic polymerization in tetrahydrofuran using sec-butyllithium as the initiator. The weight average molecular weight M_w of the samples determined by light scattering measurements were 7.9〜75.5×10^4. The molecular weight-dispersity index, M_w/M_n, (M_n, number average molecular weight), of each sample was determined by Gel permeation chromatography, which gave the values of 1.04〜1.11. The intrinsic viscosities were measured in benzene solution at several temperatures ranging from 25℃ to 55℃. The unperturbed chain dimension {<r^2_0>/M_w}^<1/2> were estimated by applying the Stockmayer-Fixman equation to the viscosity data. It was found that the value of {<r^2_0>/M_w}^<1/2> is nearly independent on temperature, giving 653×10^<-11>cm at 25℃, and 657×10^<-11>cm at 55℃. The characteristic ratio of PMeOSt chain, C_r=<r^2_0>/nl^2 (l, bond length; n, number of bond), was obtained as 12.3±0.1. It was found that the experimental value of C_r is reasonably in a good agreement with the calculate one obtained from conformational analysis based on the "rotational isomeric state" model.
東京女子大学の論文
1996-03-15