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Influence of ethanol on the thickness and free energy of film formation of DMPC foam films

Toca-Herrera, J. L. and Müller, H. -J. and Krustev, R. and Pfohl, T. and Möhwald, H.. (1999) Influence of ethanol on the thickness and free energy of film formation of DMPC foam films. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 152 (3). pp. 357-365.

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Official URL: http://edoc.unibas.ch/47086/

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Abstract

Foam films prepared from 1,2-dimirystoil-sn-glycero-3-phosphorylcholine (DMPC) dispersions in water–ethanol mixtures were investigated. Their thickness and contact angle (foam film/meniscus) were measured. Experimental results show that an increase of EtOH concentration in the film forming dispersions leads to a decrease in the film thickness. At EtOH concentrations above 40% v/v the foam films have a bilayer structure without any noticeable core of solvent. The film thickness remains constant with the further increasing of the EtOH concentration up until 50% v/v. This behaviour is corroborated by the strong increase in the contact angles (a decrease in the free energy of film formation) with increasing EtOH concentration. Ellipsometric measurements on the thickness of adsorbed DMPC monolayers and surface pressure isotherms of DMPC spread on the water–ethanol subphases show that the effective area per lipid molecule decreases, resulting in a larger monolayer thickness, when the EtOH concentration in the subphase is increased. An increase of the EtOH concentration leads to a dehydration of the DMPC molecules and a reduction in strength and range of the repulsive hydration force between the film monolayers. The film thickness and the free energy of film formation are governed by the balance of the van der Waals attraction and the repulsive hydration force between the foam film surfaces.
Faculties and Departments:05 Faculty of Science > Departement Chemie > Chemie > Biophysikalische Chemie (Pfohl)
UniBasel Contributors:Pfohl, Thomas
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:Elsevier
ISSN:0927-7757
Note:Publication type according to Uni Basel Research Database: Journal article
Identification Number:
Last Modified:21 Dec 2016 09:47
Deposited On:21 Dec 2016 09:47

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