AQUEOUS AND NONAQUEOUS MICROEMULSIONS WITH HIGH-MOLECULAR-WEIGHT ALKANES

This study extends the existing phenomenological thermodynamic model of aqueous microemulsions to nonaqueous microemulsions and examines the phase patterns when the melting temperature of the alkane oil is in the range of other liquid-liquid transition temperatures. The liquid paraffins studied are the alkane oils of greater than 17 carbons and are solid at room temperature. Water, water and ethylene glycol (4 : 1 by wt.), propylene glycol and water (4 : 1 by wt.), and propylene glycol are the four non-oleic components examined. Homogeneous polyoxyethylene nonionic surfactants and the commercial surfactants of the Brij series, Neodol series, and the LP series were used. Small-angle x-ray scattering gives evidence for the presence of microstructures in these solutions and, thus, these systems are true microemulsions at temperatures above the melting point of the alkane. Systematic paths to move from aqueous to nonaqueous microemulsions are outlined. These results are utilized in optimizing the performance requirements of an inkjet printing application.