Thin liquid films from polyoxyethylene-polyoxypropylene-block copolymer onthe surface of fused quartz

Citation
B. Diakova et al., Thin liquid films from polyoxyethylene-polyoxypropylene-block copolymer onthe surface of fused quartz, COLL SURF A, 190(1-2), 2001, pp. 61-70
Citations number
32
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
ISSN journal
09277757 → ACNP
Volume
190
Issue
1-2
Year of publication
2001
Pages
61 - 70
Database
ISI
SICI code
0927-7757(20010930)190:1-2<61:TLFFPC>2.0.ZU;2-7
Abstract
The thickness of thin liquid films, formed from solutions of a polyoxyethyl ene-polyoxypropylene-block copolymer (Lutrol F127 or poloxamer 407) on a su bstrate of fused quartz was measured using the microinterferometric method. The polymer adsorption at the air/liquid interface was studied by surface tension measurements in the absence and presence of 0.15 M NaCl. CMC and th e thickness of the adsorption layers were determined from the surface tensi on data. The polymer adsorption at the SiO2/aqueous solution interface was studied using a spectrophotometric method, based on the colored polymer-iod ine complex, The conformation of the adsorbed molecules at both interfaces was determined as being a 'brush'. The influence of the electrolyte concent ration on the thickness of the thin liquid films was investigated. It was f ound that, for NaCl concentration higher than 10(-2) M, the film thickness remained constant. A conclusion was made that 10(-2) M NaCl was the electro lyte concentration, above which the electrostatic disjoining pressure was f ully suppressed and film stability might be explained by the influence of t he steric component of the disjoining pressure. (C) 2001 Elsevier Science B .V. All rights reserved.