The universality of kinetic colloid aggregation.
Item
-
Title
-
The universality of kinetic colloid aggregation.
-
Identifier
-
AAI9000043
-
identifier
-
9000043
-
Creator
-
Lin, Min Yue.
-
Contributor
-
Adviser: David A. Weitz
-
Date
-
1989
-
Language
-
English
-
Publisher
-
City University of New York.
-
Subject
-
Physics, General | Statistics
-
Abstract
-
In this thesis the process of kinetic colloid aggregation is studied. We show that the structure of colloidal aggregates can be quantitatively described as fractals. Two kinetic regimes have been identified as universal regimes, each of them exhibits different yet distinct behavior in many key features: the fractal dimension, the cluster mass distribution, and aggregation kinetics.;Using colloidal gold, the fractal dimension and the cluster mass distribution are measured by transmission electron microscopy (TEM) analysis and scattering techniques. For DLCA, {dollar}d\sb{lcub}\rm f{rcub}{dollar} {dollar}\approx{dollar} 1.85, the cluster mass distribution exhibits a bell shape. For RLCA, {dollar}d\sb{lcub}\rm f{rcub}{dollar} {dollar}\approx{dollar} 2.1, and the cluster mass distribution has a power-law dependence N(M) {dollar}\sim{dollar} M{dollar}\sp{lcub}-3/2{rcub}{dollar}. For both regimes the cluster mass distribution obeys dynamic scaling. These properties are further studied and verified using light scattering techniques. Static light scattering is used to probe the fractal structure of aggregates, thus measuring the fractal dimension, {dollar}d\sb{lcub}\rm f{rcub}{dollar}. In addition, it is used to probe and verify the static structure factor of the aggregates. Dynamic light scattering is used to verify these key features of the aggregation process, including also the anisotropy of the aggregates reflected in the effects of their rotational diffusion, and the aggregation kinetics. Excellent agreement is found between the scattering results and the predictions based on the previous finding from colloidal gold. In addition, the aggregation kinetics measured are distinct for the two regimes: for DLCA, the characteristic cluster mass grows linearly with time; for RLCA, it grows exponentially.;A method is developed to scale dynamic light scattering data onto a master curve, whose shape depends critically on these key features, but is independent of the specific details of the colloid system. It is therefore used to demonstrate the universality of colloid aggregation. For several completely different colloids the master curves from the two regimes are markedly different; however, for each regime they are strikingly identical for these colloids. In addition, static light scattering also measures the same fractal dimension from the colloids for each regime. This provides strong evidence for the universality of the two regimes of colloid aggregation, and proves the successful application of the modern statistical theories of kinetic growth.
-
Type
-
dissertation
-
Source
-
PQT Legacy CUNY.xlsx
-
degree
-
Ph.D.
