376 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS IFSCC CONGRESS TO BE HELD SEPTEMBER 20-25, 1970 The Spanish Society of Cosmetic Chemists will host the Sixth Con- gress of the International Federation of Societies of Cosmetic Chemists on September 20-25, 1970, in Barcelona, Spain. Original unpublished papers concerning the following areas of cosmetic technology are now being solicited: 1. Color in cosmetics 2. Physical-chemical aspects of cosmetics 3. Biochemistry and dermatology 4. Practical science of cosmetics 5. Cosmetic regulations standardization of raw materials An International Jury will select the recipient of the $1000 IFSCC Award which will be •ven for the most meritorious paper presented at the Congress. To be eligible for this Award, papers must be submitted before March 20, 1970. Further information concerning manuscript requirements is available from: Sociedad Espanola de Quimicos Cosmeticos Calle Mallorca, 279 Barcelona (9) Espana

J. Soc. Cosmet. Cbem., 21, 377-391 (May 27, 1970) Stabilization of Aerosol Emulsions and Foams PAUL A. SANDERS, Ph.D.* Presented September 8-9, 1969, Seminar., St. Louis, Mo. Synopsis--It is proposed that the INTERFACIAL REGION around PROPELLANT droplets in AEROSOL EMULSIONS stabilized with MOLECULAR COMPLEXES is polymo~ lecular and consists of alternating layers of oriented water molecules and bimolecular layers of the molecular complex. The molecular complex has a LIQUID CRYSTAL STRUC- TURE and, since it is almost insoluble in either the propellant or aqueous phase, concen- trates at the interface and stabilizes the emulsion by forming essentially a solid interfacial fihn in somewhat the same way as finely divided iuorgauic solids. This hypothesis is based upon the evidence that molecular complexes have liquid crystal structures in aqueous sys- tems and that almost all aerosol emulsions and FOAMS are stabilized by substances which are practically insoluble in both the aqueous and propellant phases. INTRODUCTION The formation of molecular complexes between ionized surfac- rants and long-chain alcohols or acids has been postulated for many years (1) but it was the work of Schulman and his coworkers that provided the real .stimulus in this field. Schulman and Rideal (2) reported in 1937 that when a monomolecular film of cetyl alcohol or cholesterol was spread over an aqueous solution of sodium cetyl sulfate, the cetyl sulfate molecules penetrated the surface film of alcohol and formed a complex with the alcohol. The existence of the complex was suggested by the fact that the mixed film of cetyl sulfate and alcohol was more resistant to disruption by pressure than the film from either component alone. * Freon Products Laboratory, E. I. du Pont de Nemours & Co., Inc., Wilmington, Del. 19898. 377