ABSTRACT
This chapter summarizes the basic principles involved in the preparation of microemulsions and the origin of their thermodynamic stability. It devotes to emulsifier selection for both o/w and w/o microemulsions. The chapter also describes the physical methods that may be applied for characterization of microemulsions. It devotes to the possible enhancement of biological efficacy using microemulsions. The chapter discusses the role of microemulsions in the enhancement of wetting, spreading, and penetration. Solubilization is also another factor that may enhance the penetration and uptake of an insoluble agrochemical. The formulation of microemulsions is an art, since understanding the interactions, at a molecular level, at the oil and water sides of the interface is far from being achieved. However, some rules may be applied for selection of emulsifiers for formulating o/w and w/o microemulsions. Several physical methods may be applied for characterization of microemulsions of which conductivity, light scattering, viscosity, and nuclear magnetic resonance (NMR) are probably the most commonly used.
