Mechanism of oil-in-water emulsification using a water-soluble amphiphilic polymer and lipophilic surfactant

A new O/W (oil-in-water) emulsification system was developed using the amphiphilic polymer HHM-HEC (hydrophobically-hydrophilically modified hydroxyethyl cellulose) and a lipophilic surfactant. HHM-HEC was used as a thickener and polymeric surfactant, and the addition of small quantities of various types of nonionic lipophilic surfactant (hydrophilic-lipophilic balance < 5) decreased the droplet size of several types of oil due to a lowering of the tension at the water/oil interface. The oil droplets were held by the strong network structure of the aqueous HHM-HEC solution, preserving the O/W phase without inversion. These stable O/W emulsions were prepared without the addition of hydrophilic surfactants and thus show improved water repellency. (c) 2006 Elsevier Inc. All rights reserved.