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J. Cosmet. Sci., 49, 335-342 (September/October 1998) Surfactant-free formulations employing a synergistic complex between a hydrophobically modified, cationic cellulose ether and amylose PETER N. KONISH and JAMES V. GRUBER, Amerchol Corporation, 136 Talmadge Road, Edison, NJ, 08818-4051. Accepted for publication August 31, 1998. Synopsis This paper describes the preliminary development of a non-traditional emulsifier system, with character- istics similar to a standard oil-in-water emulsion system, employing a unique polysaccharide/polysaccharide complex formed by non-covalent crosslinking of a hydrophobically modified, water-soluble cationic cellu- lose ether (Quatrisoft © Polymer LM-200, polyquaternium-24) with amylose, a component of normal potato starch. Six oil-in-water emulsions were prepared with different emollients or pigments, and their stability was monitored by lack of separation over a period of six weeks at room temperature. A prototype skin lotion was also prepared, and monitored for stability over a six-week time period at both room temperature and 45øC via a Brookfield viscometer. INTRODUCTION The most common, commercially useful emulsions are typically oil-in-water (1,2). The oily discontinuous phase in personal care applications is typically some type of emollient or conditioner, of which many are well known (3). For typical, unadulterated water, stable suspensions are generally impossible for any extended period of time. An emulsion formed from oil and water will usually coalesce quickly back to two layers unless the droplets of oil are very small, as occurs, for example, in microemulsions (4). Even in the case of microemulsions, the desire for the oil and water to separate will typically cause separation over time. In order for water to be useful as a continuous phase, its gross molecular structure must be altered so as to improve its ability to suspend the oily phase. Classically, the water structure is altered by addition of molecules that possess both hydrophilic (water-loving) and hydrophobic (water-avoiding) components, i.e., surfactants (5). Surfactants used in personal care products can also have profound physiological effects on the proteins and lipids that comprise human skin and hair (6-9). The body generally responds quickly to Peter N. Konish's present address is Mane USA, 60 Demarest Drive, Wayne, NJ 07470. 335