一组线型聚苯乙烯和星形支化聚苯乙烯的凝胶色谱与热场流分级方法的比较

本文应用热场流分级方法,在两种不同的场强下(△T=30℃、△T=50℃),测试了一系列窄分布聚苯乙烯标样和星形支化聚苯乙烯的淋出体积V_r和分子量M的依赖关系。星形支化物的臂数不同,但臂的分子量相同,上述样品进行了GPC测试,实验表明,由TFFF得到的支化的与线型聚苯乙烯在V_r～M关系上的差别大于GPC的结果,表明链结构对扩散系数的影响大于对分子体积的影响。

COMPARISON OF GPC AND THERMAL FIELD FLOW FRACTIONATION METHODS FOR LINEAR AND STAR BRANCHED POLYSTYRENE SAMPLES

The Thermal Field-Flow fractionation (TFFF) method was used to determine the elution volume of a series of star branched polystyrene having different number of arms but the same molecular weight and polystyrene standards with narrow distribution whose molecular weight ranged from 5.0×104 to 86×104. Results were obstained by measuring at two) temperature differentials (△T=30℃ and △T=50℃) in THF. These star branched samples were also measured by means of GPC method. Comparison of the Vr-M relationship obtained from TFFF and GPC showed that the displacement of Vr-M curves for star branched and linear polystyrene is larger in TFFF than in GPC. The difference is caused by the different mechanism of separation for these two methods. As the controlling factor is the hydrodynamic volume of the polymer chain in solution for GPC, it is the diffusion coefficient of polymer moledules for TFFF. The experimental results indicate that the influence of variance of chain structure on diffusion coefficient is stronger than that on the hydrodynamic. volume and that TFFF technique maybe used as a method for characterizing branching of polymer molecules. For this purpose a proper theoretical model and more accurate experiments are needed.