Study of complex micellar systems by static and dynamic light scattering

The static and dynamic light scattering (DLS) methods were applied to study the thermodynamic properties and disperse structure of water+surfactant+solubilizer systems. It is supposed that such systems possess a micellar structure that can be used to develop new effective forms of veterinary drugs. For preparation of drugs (antibiotics) in micellar form, water solutions of the surfactant Cremafor-EL (CR) with the co-solvent dimethylacetamide (DMA) were used. To evaluate the stability of micellar solutions, we measured the light scattering intensity at 90 degrees as a function of temperature (20-80degrees Q in a water+CR+DNM system. The size distribution of micelles was determined by DLS measurements followed by DynaLS software processing. As thermodynamic characteristics of solutions, the so-called cloud point temperatures (CPT) and absolute instability temperatures (AIT) were used. Specifically, the CPT was determined as the intersection point of two linear fittings for scattering intensity vs temperature plots. AIT was determined using the inverse light scattering intensity data plotted vs temperature and then extrapolated to zero. The micelle-size distributions were measured for three types of surfactants (CF, Tween-80, and Tween-20), as well as for water+CR+DNIA systems.