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On the Structure and Dynamics of Polyelectrolyte Gel Systems and Gel-surfactant Complexes
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical Chemistry.
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis describes the results of experimental work on polyelectrolyte gels and their interaction with oppositely charged surfactants, and presents two new algorithms applicable to the simulation of colloid and polymer systems.

The model systems investigated were crosslinked poly(acrylate) (PA) and poly(styrene sulphonate) (PSS), and the surfactant was dodecyl trimethylammonium bromide (DoTAB).

Pure gel materials were studied using dynamic light scattering. It was shown that the diffusion coefficient (D) increases with increasing degree of swelling and the concentration dependence is larger than predicted by scaling arguments. For gels at swelling equilibrium D increases with increasing degree of crosslinking.

In subsequent studies on gel particles in DoTAB solution, Raman spectra were recorded at different positions in the gel. For both types of gels two distinct regions could be observed. For PA the surfactant is localised in the outer phase without any surfactant in the core, while for PSS the surfactant was distributed such that it had the same concentration relative to the polymer throughout the gel.

In a second experiment, the kinetics for the deswelling of microscopic PSS particles in DoTAB solution was studied. It was found that the final volume varied linearly with the DoTAB concentration, and the rate of volume decrease could be fitted to a single exponential indicating stagnant layer diffusion to be the rate limiting process for the deswelling of the PSS particles.

In the second part, I first describe an algorithm showing an efficient way to detect percolation in simulations, with periodic boundary conditions, using recursion.

Spherical boundary conditions is an alternative to periodic boundary conditions for systems with long-range interactions. In the last part, the possibility to use the surface of a hypersphere in four dimensions for simulations of polymer systems is investigated, and algorithms for Monte Carlo and Brownian dynamics simulations are described.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis , 2004. , p. 71
Series
Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1104-232X ; 1036
Keywords [en]
Physical chemistry, polyelectrolyte gel, microgel, dynamic light scattering, Raman spectroscopy, periodic boundary conditions, percolation, hypersphere, Monte Carlo, Brownian dynamics
Keywords [sv]
Fysikalisk kemi
National Category
Physical Chemistry
Identifiers
URN: urn:nbn:se:uu:diva-4652ISBN: 91-554-6083-6 (print)OAI: oai:DiVA.org:uu-4652DiVA, id: diva2:165387
Public defence
2004-11-19, B21, BMC, Husargatan 3, Uppsala, 10:15 (English)
Opponent
Supervisors
Available from: 2004-10-29 Created: 2004-10-29 Last updated: 2013-09-20Bibliographically approved
List of papers
1. Fast internal dynamics in polyelectrolyte gels measured by dynamic light scattering
Open this publication in new window or tab >>Fast internal dynamics in polyelectrolyte gels measured by dynamic light scattering
2005 (English)In: Polymer Bulletin, ISSN 0170-0839, E-ISSN 1436-2449, Vol. 54, no 4-5, p. 335-342Article in journal (Refereed) Published
Abstract [en]

Dynamic light scattering was used to investigate the dynamics of sodium poly(styrene sulfonate) and fully neutralized poly(acrylic acid) gels as a function of the degree of swelling and weight ratio of cross-linking agent. It was shown that the collective diffusion coefficient increases with increasing degree of swelling and that the diffusion coefficient shows stronger concentration dependence than predicted by scaling arguments. For gel samples measured at the swelling equilibrium, the diffusion coefficient increases with increasing gel concentration for both gel systems.

National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-92342 (URN)10.1007/s00289-005-0398-x (DOI)
Available from: 2004-10-29 Created: 2004-10-29 Last updated: 2017-12-14Bibliographically approved
2. Raman spectroscopy of surfactant-polyelectrolyte gel systems
Open this publication in new window or tab >>Raman spectroscopy of surfactant-polyelectrolyte gel systems
In: LangmuirArticle in journal (Refereed) Submitted
Identifiers
urn:nbn:se:uu:diva-92343 (URN)
Available from: 2004-10-29 Created: 2004-10-29Bibliographically approved
3. Single microgel particle studies demonstrate the influence of hydrophobic interactions between charged micelles and oppositely charged polyions.
Open this publication in new window or tab >>Single microgel particle studies demonstrate the influence of hydrophobic interactions between charged micelles and oppositely charged polyions.
2005 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 21, no 9, p. 3773-3781Article in journal (Refereed) Published
Abstract [en]

The binding of two cationic surfactants, dodecyltrimethylammonium bromide (DoTAB) and N-(1,1,2,2-tetrahydroperfluorodecanyl)pyridinium bromide (HFDePB), to covalently cross-linked sodium poly(styrenesulfonate) (PSS) microgels has been investigated by means of micromanipulator-assisted time-resolved light microscopy on single gels. It is demonstrated that repeated measurements on the same microgel under conditions of controlled liquid flow give highly reproducible results. The two surfactants are found to behave very differently with respect to degree of swelling, surfactant distribution in the gels, both during shrinking and at equilibrium, and kinetics of volume changes induced by them. The main difference is attributed to the presence of a hydrophobic interaction between PSS and the DoTAB micelles, absent in the case of HFDePB. Kinetic shrinking curves are recorded and analyzed using a model for steady-state transport of surfactant between the solution and the gels. Aggregation numbers for DoTAB in PSS solutions obtained from fluorescence quenching measurements are presented. A strong dependence on the surfactant-to-polyion concentration ratio is observed. Relations between surfactant binding isotherms, phase diagrams for linear polyelectrolyte/surfactant/water systems, and the binding to gels are discussed.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:uu:diva-92344 (URN)10.1021/la047316v (DOI)15835936 (PubMedID)
Available from: 2004-10-29 Created: 2004-10-29 Last updated: 2017-12-14Bibliographically approved
4. Cluster identification and percolation analysis using a recursive algorithm
Open this publication in new window or tab >>Cluster identification and percolation analysis using a recursive algorithm
1999 (English)In: Molecular Simulation, ISSN 0892-7022, E-ISSN 1029-0435, Vol. 23, no 3, p. 169-190Article in journal (Refereed) Published
Abstract [en]

A recursive algorithm for sampling properties of physical clusters such as size distribution andpercolation is presented. The approach can be applied to any system with periodic boundaryconditions, given a spatial definition of a cluster. We also introduce some modifications in thealgorithm that increases the efficiency considerably if one is only interested in percolationanalysis. The algorithm is implemented in Fortran 90 and is compared with a number ofiterative algorithms. The recursive cluster identification algorithm is somewhat slower than theiterative methods at low volume fraction but is at least as fast at high densities. The percolationanalysis, however, is considerably faster using recursion, for all systems studied. We also notethat the CPU time using recursion is independent on the static allocation of arrays, whereas theiterative method strongly depends on the size of the initially allocated arrays.

Keywords
cluster analysis, percolation, recursion, Fortran 90, algorithm, in-oil microemulsions, transitions, mercury, model
National Category
Physical Chemistry
Research subject
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-34908 (URN)10.1080/08927029908022121 (DOI)
Available from: 2008-12-16 Created: 2008-12-16 Last updated: 2017-12-06
5. Computer simulations of polymer chain structure and dynamics on a hypersphere in four-space
Open this publication in new window or tab >>Computer simulations of polymer chain structure and dynamics on a hypersphere in four-space
2005 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 122, no 18, p. 184110-Article in journal (Refereed) Published
Abstract [en]

There is a rapidly growing interest in performing computer simulations in a closed space, avoiding periodic boundary conditions. To extend the range of potential systems to include also macromolecules, we describe an algorithm for computer simulations of polymer chain molecules on S3, a hypersphere in four dimensions. In particular, we show how to generate initial conformations with a bond angle distribution given by the persistence length of the chain and how to calculate the bending forces for a molecule moving on S3. Furthermore, we discuss how to describe the shape of a macromolecule on S3, by deriving the radius of gyration tensor in this non-Euclidean space. The results from both Monte Carlo and Brownian dynamics simulations in the infinite dilution limit show that the results on S3 and in R3 coincide, both with respect to the size and shape as well as for the diffusion coefficient. All data on S3 can also be described by master curves by suitable scaling by the corresponding values in R3. We thus show how to extend the use of spherical boundary conditions, which are most effective for calculating electrostatic forces, to polymer chain molecules, making it possible to perform simulations on S3 also for polyelectrolyte systems.

National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-73804 (URN)10.1063/1.1896950 (DOI)15918697 (PubMedID)
Available from: 2007-01-16 Created: 2007-01-16 Last updated: 2017-12-14Bibliographically approved

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