Experimental Studies of Cluster-Size Distributions During Colloidal Aggregation

该项目属于分析和表面化学的一般领域，以及胶体聚集子领域。这项研究继续使用首席调查员的光学颗粒尺寸脉冲分析来表征胶体聚集过程的动力学和在不同条件下形成的聚集的结构。这种方法可以直接检验胶体絮凝的基本理论。系统地研究了两个模型体系：1)胶体聚苯乙烯微球的盐诱导凝聚反应；2)抗原-抗体凝集反应。为了检验不可逆聚集理论，团簇尺寸分布的时间演化将被记录为诸如电解质溶液的离子强度和pH的函数。粒度分析仪将得到改进，以便能够分析比目前可能的更小的颗粒。此外，光不仅将以小角度收集，而且还将以较大散射角的范围收集。这将不仅可以确定质量，而且还可以确定旋转半径，从而确定星团的分维。将描述集群结构与集群增长和集群大小分布的关系。小颗粒聚集形成较大的结构在空气和水污染、材料加工、催化、医学和生物等不同领域具有重要意义。为了促进我们对胶体聚集的理解，实验和理论研究都是必要的。光学颗粒尺寸脉冲分析可以直接测量颗粒尺寸分布和时间演化，并直接测试团簇生长的基本理论。

This project is in the general area of analytical and surface chemistry and in the subfield of colloidal aggregation. This research continues the Principal Investigator's application of optical particle size pulse analysis to characterize the kinetics of colloidal aggregation processes and the structure of aggregates formed under different conditions. This method permits direct testing of the fundamental theories of colloid flocculation. Two model systems will be studied systematically: 1) salt-induced coagulation of colloidal polystyrene microspheres; 2) antigen-antibody agglutination reactions. Temporal evolution of the cluster-size distribution will be recorded as a function of such factors as ionic strength and pH of the electrolyte solution in order to test theories of irreversible aggregation. The particle size analyzer will be improved to enable analysis of smaller particles than currently possible. In addition, light will be collected not only at small angles but also at a range of larger scattering angles. This will enable determination not only of the mass but also the radius of gyration and hence the fractal dimensionality of the clusters. The relation of cluster structure to cluster growth and cluster-size distribution will be characterized. The aggregation of small particles to form larger structures is of major importance in such diverse areas as air and water pollution, materials processing, catalysis, medicine and biology. Both experimental and theoretical studies are necessary to advance our understanding of colloidal aggregation. Optical particle size pulse analysis enables direct measurement of the particle size distribution and temporal evolution, and direct testing of the fundamental theories of cluster growth.