Nonaqueous dispersions characterization

The description of a colloid should include particle size, mobility, charge and their distributions, charge/mass ratio, electrical conductivity of the media, concentration and mobility of ionic species, the extent of a double layer, particle-particle and particle-substrate interaction forces and complete interfacial analysis. The application of classical characterization methods to nonaqueous colloids is limited and, for this reason, the techniques best suited to these systems will be reviewed. Characteristic results obtained with nonaqueous dispersions will be summarized. Physical aspects, such as space charge effects and electrohydrodynamics, will receive special attention while the relationships between chemical and physical properties will not be addressed. An application of nonaqueous colloids, the electrophoretic development of latent images, will also be discussed. 

B. Characterization of the Stability of Nonaqueous Dispersions by Calorimetric and Adsorption Measurements... 

Electrochemical methods are in general free from the difficulties associated with the current industry testing methods and present an opportunity for a relatively quick, simple, and inexpensive approach, free of temperature limitations and sample preparation issues. Electrochemistry has been previously employed to inspect lubricant condition over the life of engine oils [6, 7]. For example, electrochemical impedance spectroscopy (EIS) has been used for characterization of both engine oils [8] and nonaqueous colloidal dispersions [9]. 

Valentin C., Munoz M.C., Alarcdn J. Synthesis and characterization of vanadium-containing ZrSi04 solid solutions from gels. J. Sol-Gel Sci. Technol. 1999 15 221-230 Van Helden A.K., Jansen J.W., Vrij A. Preparation and characterization of spherical monodisperse silica dispersions in nonaqueous solvents. J. Colloid Interf. Sci. 1981 81 354-368 Woodhead J.L. Sol-gel processes to ceramic particles using inorganic precursors. J. Mater. Educ. 1984 6 887-925... 

Ionic liquid microemulsions have both the advantages of ionic liquids and microemulsion, which can overcome the inability of ionic liquids to dissolve a number of chemicals including some hydrophilic substances and then broaden the utilization of ionic liquids. Some papers reported that ionic liquid could substitute water to form nonaqueous ionic liquid microemulsion and exist as nanosized polar domains dispersed in cyclohexane with the aid of surfactant (Li et al., 2007). Gao, et al. prepared and characterized TX-IOO/H2O/I-butyl-3-methylimidazolium hexafluorophosphate (bmimPFs) microemulsion using different techniques. Their research results showed that water domains existed in the water-in-bmimPFa microemulsion, which could dissolve salts (Gao et al., 2005). 

---