Cloud point and formation of microemulsions in sucrose dodecanoate systems

The cloud temperature of aqueous sucrose dodecanoate solution (L-1695+L-595) and the effect of adding inorganic salts on the clouding phenomena were investigated as a function of the weight ratio of the hydrophilic moiety to the whole surfactant, WH/WS. The cloud temperature drastically increases with a small increase in WH/WS. It means that the solubility of sucrose dodecanoate in water is not largely influenced by the temperature but is highly dependent on WH/WS. In the presence of inorganic salts like NaCl and NaSCN, the cloud point is shifted towards higher or lower WH/WS depending on the salting-out or salting-in effect. As well as the clouding phenomenon, the HLB temperatures in water/sucrose dodecanoates (L-1695+L-595)/oil systems are less sensitive on temperature but on WH/WS. In a pseudo ternary phase diagram in the water/sucrose dodecanoates/hexadecane system at 25 °C, a microemulsion-region was determined at a fixed L-1695/L-595 ratio. The solubilization capacity of oil in microemulsions increases with the decrease in WH/WS or the surfactant layer curvature.