J. soc. cos. CHEM. 15, 473-483 (1964) SOME USES AND APPLICATIONS OF POLYGLYCEROL ESTERS IN COSMETIC AND PHARMACEUTICAL PREPARATIONS By V. K. B^B^¾AN, B.S., T. G. KAufMaN, B.S., H. L•.•Mx•, B.S. and R. J. T•aczuK, M.S.* Presented November 6, 1963, New York Chapter ABSTR&GT Polyl•lycerol esters as a class of emulsifiers having a wide range of hydrophilic-lipophilic characteristics have been prepared and charac- terized. Their properties and characteristics are discussed and com- pared with those of other groups and classes of emulsifiers. Applications and uses of the polyl•lycerol esters are discussed, with particular emphasis on their use as emulsifiers. It is shown that some esters are especially suitable for use and give the most stable W/O emul- sions with certain oils. In addition, the results of microbiological tests are given, indicating that hydrophilic polyl•lycerol esters do not interfere with the bacteriostatic action of G-11. INTRODUCTION The large number of emulsifiers that is currently available to the cosmetic and pharmaceutical industries is generally divided into four classes: anionic, nonionic, cationic and amphoteric. Typical examples of anionic emulsifiers are materials such as soaps, sodium lauryl isethionate, sulfated oils, etc. Anionic surfactants have the advantages of being use- ful in small concentrations however, they are sensitive to the presence of other ions, acids and cationic emulsifiers (1). In addition, their internal use is limited. Typical examples of nonionic emulsifiers are materials such as poly- ethylene glycol esters, sorbitan and polyoxyethylene sorbitan esters, ethoxylated fatty alcohols, alkanolamides, etc. Nonionic emulsifiers de- * Drew Chemical Corp., Boonton, N.J. 473

474 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS pend chiefly upon ether linkages and hydroxyl groups to create their hy- drophilic action. Since they do not ionize, they are claimed to be the least irritating of emulsifiers (1). However, nonionics and especially those that are ethoxylated have been reported by many authors to inac- tivate preservatives (2-7). The most frequently encountered cationic emulsifiers are quaternary ammonium compounds such as stearyl dimethyl benzyl ammonium chloride. Cationic emulsifiers are generally stable only at neutral and acid pH's, are considered to be the most irritating class of surfactants, and are not allowed for internal use (8). In addition, there are relatively few cationic edible and W/O emulsifiers available. Thus, there is a definite need for a new class of emulsifiers which is edible, covers a wide range of hydrophilic-lipophilic properties and is nonethoxy- late& This has become particularly important with the establishment of stringent controls on food, drug and cosmetic ingredients and additives. THE POLYGLYCEROL ESTERS Although polyglycerol esters have been known for over thirty years, very little has been written and even less use has been made of their unique physical and chemical properties. The major reason for this neglect is, perhaps, the difficulties of preparing materials with reproducible results (9). In recent years, suitable methods have been developed, and patents for the preparation and analysis of the polyglycerols and polyglycerol esters are now pending (10). The status of the polyglycerol esters can be summed up as follows: 1. Polyglycerol esters are prepared from glycerine, fats and oils and fatty acids. 2. Functionality can be built into the structure as desired, ranging from complete oil solubility to complete water solubility. 3. Tailor-made emulsifiers from polyglycerols can be made to suit or fit the needs of the cosmetic and pharmaceutical industries. 4. A process has been developed in our laboratories which yields products of good color, odor and flavor. 5. They are readily available, and the cost is within reason. 6. The human body is able to utilize the polyglycerol derivatives just like the common fats and oils (12). 7. No accumulation or toxic effect could be found in the usage of poly- glycerol esters even when used as the sole source of fat. As products that could achieve low or high molecular weight, solid or liquid consistency, water or oil solubility in the complete absence of toxicity, these polyglycerol esters became a welcome addition to the line of ac- ceptable emulsifiers once the F.D.A. gave the necessary clearance to their use.