Diffusion in cationic vesicle and micellar solutions- a NMR study
Doktorsavhandling, 2006

Double tailed cationic surfactants are the active component in softeners. In the beginning of the 90’s the active component in softener formulations was changed from a hydrolytically stable dialkyl dimethyl ammonium chloride (dialkyl quat) to a cleavable and biodegradable product containing ester groups in the alkyl chains (dialkyl ester quat). During the formulation process the softener surfactants will form vesicles with a large variety in size and number of bilayers in the membrane. The major part of this thesis deals with investigation, by NMR diffusometry, of the permeability of water across the vesicle membranes as a function of the molecular structure of the surfactant. It was shown that the permeability through the membranes could be controlled by changes in the molecular structure and the temperature of the system. Below the transition temperature it was found that a hydrogenated dialkyl ester quat did not allow water to permeate the membranes during the time span for NMR diffusometry experiments. The concentration of water in the bilayers was calculated for the hydrogenated dialkyl ester quat as a function of the temperature indicating that the mechanism of the water transport is changed at the transition temperature from the solubility-diffusion mechanism to a combination of the solubility-diffusion and transport through pores and dislocations in the membrane. Interactions between benzyl benzoate and dialkyl and dialkyl ester quats have also been studied by NOESY-NMR showing that benzyl benzoate is both incorporated into the hydrophobic layer of the aggregates and interacting with the quaternary head group by a π-cation interaction. A minor part of this thesis concerns the micellar kinetics of gemini surfactants. It has been shown that the life time of the micelles increases as the length of the spacer decreases. It has also been shown that the micelles grow in one direction as prolates with the largest growth for the gemini with the shortest spacer.

vesicles

Stopped-flow

micellar kinetics

water transport

DSC

Gemini surfactant

permeability

NOESY

Cationic surfactant

NMR diffusometry

extrusion

13.15 KB-salen, Kemigården 4, Chalmers
Opponent: Associate professor, Greger Orädd, Department of Chemistry, Umeå University, Sweden

Författare

Cecilia Groth

Chalmers, Kemi- och bioteknik, Teknisk ytkemi

Diffusion of water in multilamellar vesicles of dialkyl and dialkyl ester ammonium surfactants

Colloids and Surfaces A: Physicochemical and Engineering Aspects,; Vol. 228(2003)p. 64-73

Artikel i vetenskaplig tidskrift

Kinetics of the self-assembly of gemini surfactants

JOURNAL OF SURFACTANTS AND DETERGENTS,; Vol. 3(2004)p. 247-255

Artikel i vetenskaplig tidskrift

Ämneskategorier

Fysikalisk kemi

ISBN

91-7291-821-7

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 2503

13.15 KB-salen, Kemigården 4, Chalmers

Opponent: Associate professor, Greger Orädd, Department of Chemistry, Umeå University, Sweden