Rauch J, Hartung M, Privalov A F, Köhler W
Physikalisches Institut, Universität Bayreuth, D-95440 Bayreuth, Germany.
J Chem Phys. 2007 Jun 7;126(21):214901. doi: 10.1063/1.2738467.
We have performed measurements of thermal diffusion coefficients DT and solvent self-diffusion coefficients Dss in semidilute to concentrated polymer solutions. Solutes of different glass transition temperatures and solvents of different solvent qualities have been used. The investigated systems are in detail: poly(dimethyl-siloxane) in toluene, tristyrene in toluene, polystyrene in toluene, polystyrene in tetrahydrofuran, polystyrene in benzene, and polystyrene in cyclohexane. The thermal diffusion data are compared to our data and literature data for solvent self-diffusion coefficients. In all systems the concentration dependence of DT closely parallels the one of Dss which may be viewed as a local probe for friction on a length scale of the size of one polymer segment. This identifies local friction as the dominating parameter determining the concentration dependence of DT. Solvent quality, in contrast, has no influence on DT.
我们已经对半稀溶液到浓聚合物溶液中的热扩散系数DT和溶剂自扩散系数Dss进行了测量。使用了具有不同玻璃化转变温度的溶质和不同溶剂性质的溶剂。具体研究的体系有：聚二甲基硅氧烷在甲苯中、三苯乙烯在甲苯中、聚苯乙烯在甲苯中、聚苯乙烯在四氢呋喃中、聚苯乙烯在苯中以及聚苯乙烯在环己烷中。将热扩散数据与我们关于溶剂自扩散系数的数据以及文献数据进行了比较。在所有体系中，DT的浓度依赖性与Dss的浓度依赖性密切平行，Dss可被视为在一个聚合物链段大小的长度尺度上摩擦的局部探针。这表明局部摩擦是决定DT浓度依赖性的主导参数。相比之下，溶剂性质对DT没有影响。
