PHASE-BEHAVIOR OF POLYMER-SURFACTANT SYSTEMS IN RELATION TO POLYMER-POLYMER AND SURFACTANT-SURFACTANT MIXTURES

• Type: Article in International Scientific Journal
• Date: 1993

Authors

LINDMAN, B (Author) Other; KHAN, A (Author) Other; MARQUES, E (Author) FCUP; MIGUEL, MD (Author) Other; PICULELL, L (Author) Other; THALBERG, K (Author) Other

Journal

Title: Pure and Applied Chemistry

Vol. 65

Pages: 953-958

ISSN: 0033-4545

Publisher: Walter De Gruyter

Indexing

ISI Web of Knowledge - 35 Citations

Scopus - 35 Citations

Scientific classification

FOS: Natural sciences > Chemical sciences

Other information

Authenticus ID: P-001-N4S

DOI: 10.1351/pac199365050953

Abstract (EN): Novel phase diagrams of systems of water and two cosolutes of colloidal size, either macromolecules or surfactant micelles, are presented. For a mixture of two oppositely charged surfactants, a complex phase diagram is obtained with several liquid crystalline phases and equilibrium vesicles. There is a strong tendency for two surfactants to mix and form a range of structures governed by geometrical packing and electrostatic interactions. In recent years, surfactant self-assembly in the presence of different polymers has attracted a great interest, both from fundamental and applied aspects. Attractive or repulsive interactions are observed depending on the system. For the former case, dilute solutions may be analysed in terms of a binding of the surfactant to the polymer or a depression of the critical micelle concentration of the surfactant by the polymer. An important feature of these solutions is thus that the surfactant molecules, also when interacting intimately with a polymer, give micellar-type structures. The phase behavior of polymer-surfactant systems has only recently attracted greater attention but has been shown most significant for the understanding of the interactions involved. Different types of phase separation phenomena are encountered including segregative and associative types. For systems of a polyelectrolyte and an oppositely charged surfactant, an associative interaction is observed leading to phase separation into one solution concentrated in both polymer and surfactant and one very dilute solution. In the presence of an electrolyte, phase separation may be eliminated and, at higher concentrations, a polymer incompatibility type of phase separation may result. It is found fruitful to analyse the phase diagrams of polymer-surfactant systems with those of polymer-polymer and surfactant-surfactant mixtures as a basis. Analogies and differences are discussed and it is found that polymer-surfactant systems show basic similarities to polymer-polymer systems, while surfactant mixtures are different, which is due to the exchange of surfactant molecules between micelles and the formation of mixed micelles and other aggregates. Surfactant mixtures are, therefore, not displaying a segregative type of phase separation.

Language: English

Type (Professor's evaluation): Scientific