毛细管内高分子溶液的浓度分布

Concentration Distribution of Polymer Solution Confined in a Capillary

采用连续自洽场理论分析了毛细管中发生凝胶化之前的聚合物溶液浓度分布的影响因素及其规律.结果表明,体系尺寸有限时,改变聚合物链段、溶剂与壁面的相互作用参数之差,聚合物溶液浓度分布会发生贫化/吸附转变;临界作用参数与聚合物链长的倒数呈线性关系,且拟合常数与体系尺寸、聚合物溶液平均体积分数有关;聚合物分子量分布为多分散时,分子量较低的组分更容易接近容器壁面,分子量较大的组分则相反.总之,增加聚合物溶液浓度、链长,选择优良溶剂,减小体系尺寸等都会使浓度分布更加均匀.

The concentration distribution of polymer solution prior to gelling has been numerically studied with self-consistent field theory（SCFT）.As a result,under specified conditions（system size,interactions between polymer segments,solvent and wall,solution concentration）,the depletion/adsorption transition will take place.It was demonstrated that the depletion/adsorption transition depends on the difference of the interaction parameters between polymer segment and wall,and that of solvent and wall.The reciprocal of the polymer chain length was found to have a linear effect on the differences of the interaction parameters at the transition point.Furthermore,when the capillary＇s diameter is not large enough,the linear fitting constants are related with the system dimension and the average volume fraction of the polymer solution.The polymer chains with smaller molecular weight approach closer to the wall when the polymer is polydisperse.Increasing the polymer concentration and chain length,choosing better solvents or reducing the system dimension is beneficial to the solution uniformity.