Studies on the middle phase microemulsion of alkyl polyglucoside

The middle phase microemulsions of alkyl polyglucosides (APG) C8G1.46, C10G1.46, C12G1.46, C8/10G1.31 and C12/14G1.43 have been studied with the alcohol concentration scanning phase diagram. The results show that in the quaternary system of APG/alcohol/alkane/water, the increase in the alcohol concentration causes a series of phase inversion Winsor I (2) → III(3) →II( 2 ). The order of the alcohol width and the minimum alcohol concentration needed to form middle phase microemulsion is: C8G1.46>C8/10G1.31>C10G1.46>C12G1.46>C12/14G1.43. Along with the increase in APG concentrations, the minimum alcohol concentrations increase, but that for unit APG, the concentrations decrease. The alcohol width increases first and then decreases, but that for per gram of APG decreases monotonously. The longer the alcohol hydrocarbon chain, the smaller both the alcohol width and the minimum alcohol concentration to form middle phase microemulsion, but the larger the solubilizing power. With the increase in NaCl concentrations, the minimum alcohol concentration decreases, but the alcohol width is nearly unchanged. This may be explained by “salting-out” effect. The effect of alkanes is different from that of NaCl concentrations; the minimum alcohol concentration is nearly the same, but the alcohol width increases as the alkane hydrocarbon chain length increases.