1992 Volume 65 Issue 4 Pages 212-219
The effects of salinity and pH on the phase behavior, particle size, and ζ-potential of microemulsions with dimyristoylphosphatidylcholine (DMPC) were investigated. The addition of 1-propanol into DMPC/water/n-alkane systems resulted in the formation of an O/W-type microemulsion. The particle size of the microemulsion was independent of the concentration of n-alkane, but was decreased with increasing alkyl chain length of the n-alkane, the concentration of 1-propanol, and the salinity. The maximum additive concentration of n-alkane was considerably decreased at the regions above pH=7. The surface charge density of microemulsion changed from positive to negative with increasing pH, and became zero at pH=3.2. The particle size of the DMPC microemulsion was at its maximum in the isoelectric region (pH=3-7). It was found that the properties of the microemulsions are dependent extensively on both salinity and pH.
