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Regular and Irregular Deswelling of Polyacrylate and Hyaluronate Gels Induced by Oppositely Charged Surfactants
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
2008 (English)In: Journal of Colloid and Interface Science, ISSN 0021-9797, Vol. 325, no 2, 316-323 p.Article in journal (Refereed) Published
Abstract [en]

The deswelling kinetics of macroscopic polyacrylate (PA) gels in solutions of dodecyltrimethylammonium bromide (C(12)TAB) and cetyltrimethylammonium bromide (C(16)TAB), with and without added sodium bromide, as well as hyaluronate (HA) gels in solutions of cetylpyridinium chloride (CPC) are investigated. Additional data are also provided by small-angle X-ray scattering and microgel experiments. The purpose is to study the deswelling behavior of (1) regularly deswelling gels, for which the deswelling is successfully described using a core/shell model earlier employed for microgels, and (2) irregularly deswelling gels, where the gel turns into a balloon-like structure with a dense outer layer surrounding a liquid-filled core. For regularly deswelling gets, the deswelling of PA/C(12)TAB is found to be controlled by diffusion through both stagnant layer and collapsed surface phase, while for PA/C(16)TAB it is found to be controlled mainly by the latter. The difference in deswelling rate between the two is found to correspond to the difference in surfactant diffusion coefficient in the surface phase. Factors found to promote irregular deswelling, described as balloon formation, are rapid surfactant binding, high bromide and surfactant concentration, longer surfactant chain length, and macroscopic gel size. Scattering data indicating a cubic structure for HA/CPC complexes are reported.

Place, publisher, year, edition, pages
2008. Vol. 325, no 2, 316-323 p.
Keyword [en]
CTAB, C(16)TAB, DTAB, C(12)TAB, CPC, SAXS, hyaluronic acid, polyacrylic acid, deswelling kinetics
National Category
Pharmaceutical Sciences
URN: urn:nbn:se:uu:diva-96227DOI: 10.1016/j.jcis.2008.05.054ISI: 000258553900003PubMedID: 18565536OAI: oai:DiVA.org:uu-96227DiVA: diva2:170728
Available from: 2007-09-27 Created: 2007-09-27 Last updated: 2009-10-07Bibliographically approved
In thesis
1. Interaction between Crosslinked Polyelectrolyte Gels and Oppositely Charged Surfactants
Open this publication in new window or tab >>Interaction between Crosslinked Polyelectrolyte Gels and Oppositely Charged Surfactants
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The interactions between anionic, crosslinked gels and cationic surfactants have been investigated. When exposed to oppositely charged surfactant, the gel collapses into a dense complex of polyion and micelles. During deswelling, the gel phase separates into a micelle-rich, collapsed surface phase, and a swollen, micelle-free core, both still part of the same network. As more surfactant is absorbed, the surface phase grows at the expense of the core, until the entire gel has collapsed. Polyacrylate (PA) gels with dodecyl- (C12TAB), and cetyltrimethylammonium bromide (C16TAB), as well as hyaluronate gels with cetylpyridinium chloride, have been studied.

Kinetic experiments have been performed on macro- as well as microgels, using micromanipulator assisted light microscopy for the latter. A surfactant diffusion controlled deswelling model has been employed to describe the deswelling. The deswelling kinetics of PA microgels have been shown to be controlled by surfactant diffusion through the stagnant layer surrounding the gel, as the surface phase is relatively thin for the major part of the deswelling. For macroscopic PA gels the surface phase is thicker, and the kinetics with C12TAB were therefore also influenced by diffusion through the surface phase, while for C16TAB they were dominated by it.

Relevant parameters have also been determined using equilibrium experiments. An irregular, balloon-forming deswelling pattern, mainly found for macrogels, as well as unexpectedly long lag times and slow deswelling for microgels, are reported and discussed.

The microstructure of fully collapsed PA/C12TAB complexes has been studied using small-angle X-ray scattering. A cubic Pm3n structure was found at low salt concentration, which melted into a disordered micellar phase as the salt concentration was increased. Further increasing the salt concentration dissolved the micelles, resulting in no ordering.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2007. 68 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Pharmacy, ISSN 1651-6192 ; 62
Pharmaceutical chemistry, gel, polyelectrolyte, surfactant, deswelling, kinetics, phase separation, volume transition, ion-exchange, diffusion, liquid crystal, SAXS, cubic Pm3n, Farmaceutisk kemi
urn:nbn:se:uu:diva-8216 (URN)978-91-554-6970-2 (ISBN)
Public defence
2007-10-19, B22, BMC, Husargatan 3, Uppsala, 09:15
Available from: 2007-09-27 Created: 2007-09-27Bibliographically approved

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