Document Detail


Hysteresis during contact angles measurement.
MedLine Citation:
PMID:  20060981     Owner:  NLM     Status:  PubMed-not-MEDLINE    
Abstract/OtherAbstract:
A theory, based on the presence of an adsorbed film in the vicinity of the triple contact line, provides a molecular interpretation of intrinsic hysteresis during the measurement of static contact angles. Static contact angles are measured by placing a sessile drop on top of a flat solid surface. If the solid surface has not been previously in contact with a vapor phase saturated with the molecules of the liquid phase, the solid surface is free of adsorbed liquid molecules. In the absence of an adsorbed film, molecular forces configure an advancing contact angle larger than the static contact angle. After some time, due to an evaporation/adsorption process, the interface of the drop coexists with an adsorbed film of liquid molecules as part of the equilibrium configuration, denoted as the static contact angle. This equilibrium configuration is metastable because the droplet has a larger vapor pressure than the surrounding flat film. As the drop evaporates, the vapor/liquid interface contracts and the apparent contact line moves towards the center of the drop. During this process, the film left behind is thicker than the adsorbed film and molecular attraction results in a receding contact angle, smaller than the equilibrium contact angle.
Authors:
M Elena Diaz; Javier Fuentes; Ramon L Cerro; Michael D Savage
Publication Detail:
Type:  Journal Article     Date:  2009-12-04
Journal Detail:
Title:  Journal of colloid and interface science     Volume:  343     ISSN:  1095-7103     ISO Abbreviation:  J Colloid Interface Sci     Publication Date:  2010 Mar 
Date Detail:
Created Date:  2010-02-15     Completed Date:  2010-04-26     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0043125     Medline TA:  J Colloid Interface Sci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  574-83     Citation Subset:  -    
Copyright Information:
2009 Elsevier Inc. All rights reserved.
Affiliation:
Departamento de Ingenieria Quimica y Textil, Universidad de Salamanca, Plaza de los Caidos 1-5, Salamanca, 37008, Spain. e.diaz@usal.es
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