Polysaccharide/Surfactant complexes at the air-water interface – Effect of the charge density on interfacial and foaming behaviors

Abstract : The binding of a cationic surfactant (hexadecyltrimethylammonium bromide, CTAB) to a negatively charged natural polysaccharide (pectin) at air-solution interfaces, was investigated on single interfaces and in foams, versus the linear charge densities of the polysaccharide. Beside classical methods to investigate polymer/surfactant systems, we applied, for the first time concerning these systems, the analogy between the small angle neutron scattering by foams and the neutron reflectivity of films to measure in situ film thicknesses of foams. CTAB/pectin foam films are much thicker than that of the pure surfactant foam film but similar for highly and lowly charged pectin/CTAB systems despite the difference in structure of complexes at interfaces. The improvement of the foam properties of CTAB bound to pectin is shown to be directly related to the formation of pectin-CTAB complexes at the air-water interface. However, in opposition to surface activity, there is no specific behavior for the highly charged pectin: foam properties depend mainly upon the bulk charge concentration, while the interfacial behavior is mainly governed by the charge density of pectin. For the highly charged pectin, specific cooperative effects between neighboring charged sites along the chain are thought to be involved in the higher surface activity of pectin/CTAB complexes. A more general behavior can be obtained at lower charge density either by using a lowly charged pectin or by neutralizing the highly charged pectin in decreasing pH. .
Complete list of metadatas

Cited literature [28 references]  Display  Hide  Download

https://hal.archives-ouvertes.fr/hal-00482587
Contributor : François Boué <>
Submitted on : Monday, May 10, 2010 - 8:05:28 PM
Last modification on : Wednesday, February 19, 2020 - 11:24:05 AM
Long-term archiving on: Thursday, September 16, 2010 - 1:46:51 PM

Files

ropers_reviewed_1.pdf
Files produced by the author(s)

Identifiers

Collections

Citation

Marie-Hélène Ropers, Bruno Novales, François Boué, Monique A.V. Axelos. Polysaccharide/Surfactant complexes at the air-water interface – Effect of the charge density on interfacial and foaming behaviors. Langmuir, American Chemical Society, 2009, 24 (22), pp.12849-12857. ⟨10.1021/la802357m⟩. ⟨hal-00482587⟩

Share

Metrics

Record views

328

Files downloads

381