四臂星形聚苯乙烯在良溶剂和0溶剂中分子扩散的光子相关光谱的研究

用光子相关光谱研究了四臂星形聚苯乙烯在良溶剂(四氢呋喃THF)和θ溶剂(环己烷CH)中扩散系数与溶剂的浓度和温度的依赖关系。用累积量方法分析光子相关数据给出了多分散样品的Z均扩散系数。在θ溶剂中,高于或低于θ温度时,聚合物在溶液中的分子扩散分别表现出具有在良溶剂与不良溶剂中的行为。外推浓度至零,得到无限稀时不同温度的分子扩散系数,借助Stokes-Einstein方程,给出了聚合物的流体力学半径。通过InD对I/T作图,得到了星形聚苯乙烯在THF与CH中的扩散活化能。

Photon Correlation Spectroscopy Study of 4-Arm Star Polystyrene Molecular Diffusion in Good and θ Solvents

The paper reports the concentration and temperature dependence on diffusion coefficients for 4-arm star polystyrene in a good and a 0 solvents (THF and CH)studied by cumulent method. In 0 solvent, when T>0 or T<0, the molecular diffusion behaves as in a good solvent and a poor solvent. Extrapolating concentration to zero, we obtained the molecular diffusion coefficients at infinite dilution at various temperatures. With Stokes-Einstein equation, we gave the hydrodynamic radii of 4-arm star polystyrene in different solvents. InD was plotted against 1/T, we got the values of diffusion activation energy EnTHF= 7. 07 kJ/mol, EnCH=14. 06 kJ/mol, for 4-arm star polystyrene in THF and CH respectively.