Study on Surface Activity and Critical Aggregation Concentration of Sucrose Esters Containing Different Isomers of Mono-, Di- and Polyesters

Abstract We have studied the surface properties of a series of synthesized sucrose esters with different hydrophobic chain lengths (C12–C18). The critical aggregation concentration (CAC) values for sucrose stearates and palmitates primarily decrease and then increase, but the surface tension (γCAC) values all increase with decreasing the proportion of monoesters. However, in the case of sucrose laurates, the CAC values decrease with the decrease in the proportion of monoesters. Except for sucrose stearate, the CAC values for other sucrose esters decrease but the the γCAC values increase with the increase of the tail length when the proportion of monoesters is remained unchangeable. In order to further interpret the observation, the lowest-energy conformations generated by MM2 for sucrose mono-, di- and triester are given. In comparison with monoester, the molecular dimensions of diester and triester are more bulky and the structures are more three-dimensional. The sucrose esters containing lower proportion of monoesters can produce higher cross-sectional area per molecule than the monoester, and therefore have higher surface tension.