Phase behaviour of oppositely charged polymer/surfactant mixtures
University Chemical Laboratory -
Lensfield Road, Cambridge, CB2 1EW, UK
2 Unilever R&D Port Sunlight - Bebington, Wirral, CH63 3JW, UK
Accepted: 2 September 2003
We demonstrate that many of the features of associative phase separation seen experimentally for oppositely charged polymer/surfactant mixtures can be recovered with a Poisson-Boltzmann cell model for macroion solutions, extended to incorporate a polyelectrolyte component. Whilst the phase transition is driven by entropy and electrostatic effects, we find that the extent of phase separation is sensitive to excluded-volume effects and to the short-range polymer-micelle interaction. Our model also makes predictions for trends in the critical aggregation concentration which are in reasonable agreement with experiment.
PACS: 64.75.+g – Solubility, segregation, and mixing; phase separation / 82.70.Uv – Surfactants, micellar solutions, vesicles, lamellae, amphiphilic systems (hydrophilic and hydrophobic interactions) / 82.35.Rs – Polyelectrolytes
© EDP Sciences, 2003