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Bilayers with Surfa...
Bilayers with Surfactant-induced Pores and Demixing in Micelles : Studies of Segregation in Amphiphile Systems
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- Kadi, Mari, 1975- (författare)
- Uppsala universitet,Fysikalisk-kemiska institutionen
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Almgren, Mats (preses)
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Hansson, Per (preses)
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- Olsson, Ulf, Professor (opponent)
- Fysikalisk kemi 1, Lund
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(creator_code:org_t)
- ISBN 9155457282
- Uppsala : Acta Universitatis Upsaliensis, 2003
- Engelska 55 s.
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Serie: Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, 1104-232X ; 884
- Relaterad länk:
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https://uu.diva-port... (primary) (Raw object)
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https://urn.kb.se/re...
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Abstract
Ämnesord
Stäng
- The focus of this thesis has been on the effects of segregation in mixtures of amphiphilic molecules. Two different systems were investigated: fluorocarbon-hydrocarbon surfactant mixtures and lipid-surfactant mixtures.In fluorocarbon-hydrocarbon surfactant mixtures the repulsive interactions between the chains can lead to a demixing into different types of coexisting micelles, fluorocarbon rich and hydrocarbon rich. From NMR self-diffusion measurements such a demixing was found to occur in the mixture of the partially fluorinated surfactant HFDePC and C16TAC. We furthermore suggested a demixing also within the micelles to explain 19F-NMR line width data and results from neutron scattering.In lipid-surfactant mixtures, a segregation of the molecules may instead be caused by a difference in the preferred curvature of the lipid and the surfactant residing within the same aggregate. Using a surfactant selective electrode, binding isoterms of four different cationic surfactants (C12TAC, C14TAC, C16TAC and HFDePC) to preformed lipid (GMO) vesicles were determined. Perforated vesicles were observed by cryo-TEM in the mixture with C16TAC. To explain the results from the binding isoterms, the formation of pores in the bilayer was regarded as a cooperative process, similar to micelle formation. The surfactant accumulates at the edges of the pores, and increasing the surfactant concentration results in an increased number of pores with a constant surfactant/lipid ratio at the edges.The lipid-surfactant mixtures were also studied at the solid/solution interface using AFM. An adsorbed mesh structure, a counterpart to the bulk perforated lamellar phase, was observed for the first time.
Ämnesord
- NATURVETENSKAP -- Kemi -- Fysikalisk kemi (hsv//swe)
- NATURAL SCIENCES -- Chemical Sciences -- Physical Chemistry (hsv//eng)
Nyckelord
- Physical chemistry
- fluorocarbon surfactants
- amphiphile mixtures
- perforated bilayers
- segregation
- NMR
- surfactant selective electrode
- cryo-TEM
- SANS
- AFM
- Fysikalisk kemi
- Physical chemistry
- Fysikalisk kemi
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