A review of the rheology of the lamellar phase in surfactant systems

The rheology of the liquid crystal lamellar phase has been studied in a wide range of systems including non-ionic, anionic and cationic surfactants and block co-polymers. This review summarises the main advances in this area over the past twenty years and includes examples of the rheo-optical techniques, which help to elucidate the changes in microstructural conformation taking place in the lamellar phase during shear. Particular emphasis is given to the microstructural change of the lamellar phase from sheet-like bilayers to dispersed multilamellar vesicles (droplets). Examples of this transition are provided for both surfactant and block co-polymer systems. The review highlights similarities in the rheological signatures of the transition for different systems and also summarises the variation in behaviour of the lamellar phase at different surfactant concentrations and on the addition of salt. (C) 2002 Elsevier Science B.V. All rights reserved.