Micellar and solubilizing behaviour of Pluronic L-64 in water

The temperature effect in aqueous solutions of a polyoxyethylene—polyoxypropylene—poloxyethylene (POE—POP—POE) block copolymer, Pluronic L-64 in water, was examined by means of viscosity, sedimentation, scattering and sound velocity measurements. Micelle formation in L-64 was strongly dependent on concentration and temperature. An increase in temperature shifted the micelle formation markedly to lower concentration; the micelle grew large particularly at temperatures near the cloud point. The viscosity data were analyzed to estimate various parameters, including the hydrated micellar volume, hydration number, hydrodynamic radius, etc. An increase in diazepam solubility in L-64 micelles with increasing concentration and temperature was observed.