Physicochemical Studies on Mixed Surfactant Microemulsion Systems III. Phase behaviours of Microemulsions derived from a Nonionic Surfactant (Brij-56) and the influence of Ionic Surfactants, Cosurfactants, Oil, Temperature and Additives

摘要

Phase behaviour of a single surfactant, polyoxyethylene (10) cetyl ether (Brij-56)/ 1-butanol/ n-heptane/water microemulsion sstem is presented in two dimensions by plotting weight percent of the surfactant (Brij-56) against the weight percent of cosurfactant (1-butanol). Phase characteristics have been noted with varying a (ratio of oil/ oil+water) (w/w) at 30 deg C. A typical WI -- > WIV-- > WII transition with increase in 1-butanol weight percent at high Brij-56 content (w/w). and a WI -- > Will -- > WII transition at low Brij-56 content (w/w) have been observed. The effect of adding ionic surfactants, sodium dodecyl benzene sulfonate (SDBS), sodium dodecyl sulfate (SDS), sulfosuccinic acid bis[2-ethylhexyl] ester, sodium salt (AOT), didodecyldimehyl ammonium bromide (DDAB), cetyltrimethyl ammonium bromide (CTAB) on the phase behaviour of this system has been investigated. No three phase microemulsion formation (Will) has been observed. Formation of a three phase (fish head) has been observed in presence of another nonionic surfactant polyoxyethylene (2) cetyl ether(Brij-52). The effect of type of oils (cyclohexane, isobutyl benzene, isopropyl myristate), oil content (a), temperature, cosurfactants (1-propanol, 1-pentanol, 1-hexanol and butyl lactate) and additives (sodium sulfate, Na,SO, and sodium cholate, NaC) on the phase behaviour of single (Brij-56/l-butanol/ n-heptane/water) and mixed (Brij-56/SDBS/l-bu-tanol/n-heptane/water) surfactant systems has been investigated with the help of fish-tail diagram. Effect of additives (urea and Na_2SO_4) on the phase behaviour of single and mixed surfactant systems at fixed surfactant concentration and a has also been studied at different temperatures. An attempt has been made to explain these results in the light of hydrophilic- lipophilic balance and the mutual solubility of the componests. The structural aspects have been investigated with the help of conductivity and viscosity measurements.