US-Czechoslovakia Research: Identification and Utilization of Critical Conditions for Polymer Characterizations

这个美国-捷克斯洛伐克化学研究项目是由范德比尔特大学的David Hunkeler博士和斯洛伐克科学院高分子研究所的Dusan Berek博士共同完成的。研究人员将使用色谱不可见性的概念来确定混合元素中聚合物的保留体积与分子量无关的关键条件。他们将比较产生临界条件的两种方法：(1) Belenki方法，通过改变二元混合物的洗脱强度来控制大分子的吸附和排除；(2)Hunkeler-Macko-Berek技术，通过改变流动相的热力学质量来平衡吸附和沉淀的自由能与再溶解和排除的自由能。还将评估温度、压力和样品浓度对所选聚合物在其临界条件下的行为的影响。临界条件将与表征溶液中大分子的性质相关。所确定的关键条件将根据分子量和组成应用于聚合物共混物、嵌段共聚物和接枝共聚物的分离和鉴定。这个聚合物研究项目通过使美国和东欧的领先专家在共同感兴趣和能力强的领域结合互补的人才和汇集资源，实现了推进科学知识的计划目标。

This U.S.-Czechoslovakia research project in chemistry is between Dr. David Hunkeler of Vanderbilt University and Dr. Dusan Berek of the Polymer Institute, Slovak Academy of Science. The researchers will use the concept of chromotographic invisibility to identify critical conditions where the retention volume of a polymer in a mixed element is independent of molecular weight. They will compare two approaches for generating critical conditions: (1) Belenki's method where the elution strength of the binary mixture is varied to control the adsorption and exclusion of the macromolecules and (2) the Hunkeler-Macko-Berek technique where the thermodynamic quality of the mobile phase is varied to balance the free energy of adsorption and precipitation with that of redissolution and exclusion. The influence of temperature, pressure and sample concentration on the behavior of selected polymers at their critical conditions will also be evaluated. The critical conditions will be correlated with properties which characterize the macromolecule in solution. The identified critical conditions will then be applied to the separation and identification of polymer blends and block and graft copolymers according to their molecular weight and composition. This project in polymer research fulfills the program objective of advancing scientific knowledge by enabling leading experts in the United States and Eastern Europe to combine complementary talents and pool resources in areas of strong mutual interest and competence.