Experimental Studies of Cluster-Size Distributions During Colloidal Aggregation

这个项目属于分析化学和表面化学的一般领域，属于胶体聚集的子领域。这项研究延续了首席研究员的应用光学粒度脉冲分析来表征胶体聚集过程的动力学和不同条件下形成的聚集体的结构。这种方法可以直接检验胶体絮凝的基本理论。本文将系统研究两种模型体系：1)聚苯乙烯胶体微球的盐致混凝；2)抗原抗体凝集反应。簇大小分布的时间演变将被记录为离子强度和电解质溶液pH等因素的函数，以测试不可逆聚集的理论。粒度分析仪将得到改进，以能够分析比目前可能的更小的颗粒。此外，光不仅可以在小角度收集，还可以在较大的散射角范围内收集。这不仅可以确定质量，还可以确定旋转半径，从而确定星团的分形维数。研究了集群结构与集群生长和集群大小分布的关系。小颗粒聚集形成更大的结构在空气和水污染、材料加工、催化、医学和生物学等不同领域具有重要意义。实验和理论研究对于提高我们对胶体聚集的认识都是必要的。光学粒度脉冲分析可以直接测量粒度分布和时间演变，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.