Advanced

Molecular Exchange in Colloidal Dispersions

Evilevitch, Alex LU (2001)
Abstract
This thesis is a study of molecular exchange between the aggregates in a colloidal dispersion. The problem of oil molecular transport at resolubilization of big oil drops by smaller microemulsion droplets is considered as an experimental model system. The resolubilization kinetics was measured through a temperature jump into a droplet microemulsion phase from a two-phase region of microemulsion droplets and separating oil. The relaxation process was monitored by following the turbidity of the system. A quantitative model for the solubilization kinetics was formulated on the basis of experimental observations. The effects of concentrations and sizes of droplets are treated within a framework of a cell model. New computer simulation approach... (More)
This thesis is a study of molecular exchange between the aggregates in a colloidal dispersion. The problem of oil molecular transport at resolubilization of big oil drops by smaller microemulsion droplets is considered as an experimental model system. The resolubilization kinetics was measured through a temperature jump into a droplet microemulsion phase from a two-phase region of microemulsion droplets and separating oil. The relaxation process was monitored by following the turbidity of the system. A quantitative model for the solubilization kinetics was formulated on the basis of experimental observations. The effects of concentrations and sizes of droplets are treated within a framework of a cell model. New computer simulation approach for molecular exchange studies is also introduced. The simulation model describes discreet spherical aggregates moving in a Brownian motion at the same time as small molecules, such as oil or surfactant, are allowed to exchange between the aggregates. The model allows a detailed study of the local exchange between neighbor micelles as well as the collective long-range exchange. The theoretical analysis from both models showed that as a result of high droplet concentration, the molecular exchange between the droplets occurs via diffusive monomer transport only in the vicinity of the droplets’ surface, and not across the entire system as predicted by the infinite dilution limit approximation. A quantitative agreement between the simulation, the cell model, and experiment was obtained in description of the resolubilization process. In addition, structure and transport properties of weakly charged oil-in-water microemulsion droplets, were also studied. Static and dynamic properties such as osmotic pressure, osmotic compressibility, self-diffusion, collective diffusion, and zero shear viscosity were analyzed by experimental and theoretical techniques. (Less)
Please use this url to cite or link to this publication:
author
opponent
  • Prof Gelbart, William, Dept. of Chemistry & Biochemistry, University of California, Los Angeles
organization
publishing date
type
Thesis
publication status
published
subject
keywords
charged micoremulsion droplets, kinetics, mechanism., Physical chemistry, Fysikalisk kemi, molecular transport, cell model, infinite dilution limit, turbidity measurements, oil solubilization, computer simulation, modeling, monomer diffusion, molecular exchange, Microemulsion droplets, oil droplets
pages
162 pages
publisher
Alex Evilevitch, Beväringsgatan 1, 212 33 Malmö, Sweden,
defense location
Sal A, Kemicentrum
defense date
2001-11-27 13:15
ISBN
91-7874-154-8
language
English
LU publication?
yes
id
a11dbaae-3f8f-481a-ba40-d2923b0702a6 (old id 42124)
date added to LUP
2007-06-20 14:56:17
date last changed
2016-09-19 08:45:12
@phdthesis{a11dbaae-3f8f-481a-ba40-d2923b0702a6,
  abstract     = {This thesis is a study of molecular exchange between the aggregates in a colloidal dispersion. The problem of oil molecular transport at resolubilization of big oil drops by smaller microemulsion droplets is considered as an experimental model system. The resolubilization kinetics was measured through a temperature jump into a droplet microemulsion phase from a two-phase region of microemulsion droplets and separating oil. The relaxation process was monitored by following the turbidity of the system. A quantitative model for the solubilization kinetics was formulated on the basis of experimental observations. The effects of concentrations and sizes of droplets are treated within a framework of a cell model. New computer simulation approach for molecular exchange studies is also introduced. The simulation model describes discreet spherical aggregates moving in a Brownian motion at the same time as small molecules, such as oil or surfactant, are allowed to exchange between the aggregates. The model allows a detailed study of the local exchange between neighbor micelles as well as the collective long-range exchange. The theoretical analysis from both models showed that as a result of high droplet concentration, the molecular exchange between the droplets occurs via diffusive monomer transport only in the vicinity of the droplets’ surface, and not across the entire system as predicted by the infinite dilution limit approximation. A quantitative agreement between the simulation, the cell model, and experiment was obtained in description of the resolubilization process. In addition, structure and transport properties of weakly charged oil-in-water microemulsion droplets, were also studied. Static and dynamic properties such as osmotic pressure, osmotic compressibility, self-diffusion, collective diffusion, and zero shear viscosity were analyzed by experimental and theoretical techniques.},
  author       = {Evilevitch, Alex},
  isbn         = {91-7874-154-8},
  keyword      = {charged micoremulsion droplets,kinetics,mechanism.,Physical chemistry,Fysikalisk kemi,molecular transport,cell model,infinite dilution limit,turbidity measurements,oil solubilization,computer simulation,modeling,monomer diffusion,molecular exchange,Microemulsion droplets,oil droplets},
  language     = {eng},
  pages        = {162},
  publisher    = {Alex Evilevitch, Beväringsgatan 1, 212 33 Malmö, Sweden,},
  school       = {Lund University},
  title        = {Molecular Exchange in Colloidal Dispersions},
  year         = {2001},
}