NONIONIC POLYMERS AND SURFACTANTS - SOME ANOMALIES IN TEMPERATURE-DEPENDENCE AND IN INTERACTIONS WITH IONIC SURFACTANTS

Nonionic polymers and surfactants in aqueous systems show in a large number of properties unusual or 'anomalous' temperature dependences which are briefly reviewed. It is also reported that these solutes in the presence of ionic amphiphilic cosolutes show anomalous effects such as a strong synergistic ionic surfactant-electrolyte effect in the phase behaviour and the formation of stiff gels at higher temperature. With the aim of understanding the effect of ethylene oxidecontaining and related systems in general, including homogeneous solutions, microheterogeneous self-assembled solutions and macroscopic interfaces, a general discussion of possible interactions is presented. Different observations suggest that in all these systems, the solute or interface becomes less hydrophilic at higher temperature, which is in agreement with recent quantumchemical calculations. The effects of conformational equilibria on phase diagrams is considered and in particular it is shown that complex phase equilibria of nonionic polymer-ionic surfactant systems can be rationalized by a simple model. © 1990.