Reological properties of the reverse mesophases of the Pluronic L64 p xylene – water system

The behaviour of reverse micellar solution and reverse hexagonal and lamellar liquid crystal phases in pluronic L64/water/p-xylene ternary system was investigated by rheological techniques. Samples with an increasing water content along the amphiphilic copolymer-lean side of the ternary phase diagram were analysed at dif- ferent temperatures and a different behaviour was evidenced by both dynamic and steady tests for each con- sidered phase, depending on the morphology of structure (micellar, lamellar, hexagonal phases). It was observed that the reverse micelles size increases with increasing water concentration and decreases with increasing tem- perature, without any phase transition. On the contrary the normal micelles become anisometric on tempera- ture, showing a transition to a liquid crystalline phase. The observed mechanical spectra of the liquid crystalline phases are typical of hexagonal and lamellar phases according to the literature [1, 2]. A phase transition with temperature was found for both liquid crystalline phase (lamellar and hexagonal) by rheological tests and was confirmed by ocular inspection.