短链聚苯乙烯稀溶液粘度及渗透压行为

本文用动态膜渗透压及粘度法测定了短链聚苯乙烯的分子量Mn, 第二virial系数A2及特性粘数η], 得到聚苯乙烯(2.5×10^3, 均方末端距以及扩张因子αs均与报道值一致。本工作表明, 分子量大约在400-1.5×10^4之间, 为聚苯乙烯从小分子到高分子的过渡区, 此时短链聚苯乙烯以蠕虫形链存在于溶液中。

Viscosity and osmotic pressure behavior of short chain polystyrene

The no.-av. mol. wt. (M), second virial coefficients A2, and intrinsic viscosity h] of short-chain polystyrene (I) were measured by dynamic membrane osmometry and viscometry. The h]-M relations for I (2.5 ?103 < M < 1.5 ?104) in PhMe, CHCl3, and acetone were close to one another, and in agreement with the literature data for I in cyclohexane at 34.5? which was represented as h] = 8.8 ?10-2 M0.50. The value of A2 increased rapidly with decreasing M. The osmotic pressure results combined with literature data yielded A2os= KM-1.6, and A2oswas always higher than that from light scattering. The mean square radius of gyration, end-to-end distance, and expansion factor calculated from viscosity values according to Flory viscosity theory and the Stockmayer-Fixman equation were consistent with the literature. The results implied that in the region of M from 400 to 1.5 ?104 for I, there was a transition from small mol. to macromol., and the short-chain I in dilute solution existed as a wormlike chain.