]. Soc. Cosmet. Chem., 27, 543-553 (November 1976) Sorption of A Cationic Polymer by Stratum Corneum JOSEPH A. FAUCHER, Ph.D. and E. DESMOND GODDARD, Ph.D.* Presented, in part, May 30, 1975, SCC Seminar, St. Louis, Mo. Synopsis: A study was made of the SORPTION of a CATIONIC CELLULOSE POLY- MER from aqueous solutions by several types of MAMMALIAN STRATUM CORNEUM. The effects of surfactants and other additives were investigated, as well as were the in- fluence of concentration and molecular weight of the polymer. Considerably more ma- terial is sotbed than can be accounted for by postulating monolayer coverage of the sub- strate. The data were found to be explained better by a mechanism of diffusion of the polymer into the outer layers of the stratum corncure than by multilayer absorption. INTRODUCTION It has been known for some time that cationic surfactants and polymers are quickly bound to the skin and tenaciously held. However, data previously available in the literature (1-3) are only qualitative, and give litfie insight into the mechanism of adsorption. Some preliminary kinetic observations from this laboratory have been reported earlier (4) they dealt with the sorption by *Union Carbide Corp., Tarrytown Technical Center, Tarrytown, N.Y. 10591. 543

544 JOURNAL OF THE SOCIETY' OF COSMETIC CHEMISTS mammalian stratum corneum of Polymer JR,* a cationic cellulose ether de- rivative. The present work is a more detailed investigation of the sorption of this polymer, including the influence of other additives. EXPERIMENTAL Samples of stratum corncure were obtained by careful removal of the outer layer of several types of mammalian skin as follows. 1. Fetal Pigskin* was obtained frozen. Upon warming of the whole skin, the stratum corneum layer could be readily peeled off in large pieces by hand. Sixteen mm disks were punched out with a cork-borer. A typical desk was 18 gm thick and weighed 2.8 mg, corresponding to a density of 0.8. 2. Human st'ratum comeurn was obtained in the form of small irregular pieces stripped from the legs and arms of a subject who had been sunburned in the summer time. A typical piece, weighing 1.7 mg, had the form of a rectangle 6 by 9 mm. The thickness was about 25 /xm, corresponding to a density of 1.24. 3. Neonatal rat stratum corneum: live young rats were obtained.* They were not more than i to 2 days old. The animals were sacrificed by being placed in an atmosphere of COsfor several hours after death the whole skin was removed by a surgical scalpel. The skin was placed in a desiccator jar and exposed to ammonia vapor for about I to 3 h. Following this, the skins were put in water and the epidermal layer was gently separated from the dermis. The epidermis so obtained was floated on the surface of a pan of water. After an hour, the membrane was removed by bringing up a metal screen under it. The membrane was placed top down on a wet paper towel and the screen removed. At this point the "Malpighian layer" could be gently scraped off, leaving the desired stratum corneum on the towel. The paper and stratum corneum were placed again in water until separation occurred. The stratum corneum layer was recovered by a small Teflon•** screen and air dried. A typical piece of stratum corneum was about 25/xm thick and 5 x 6 cm in area. It weighed about 20 mg, corresponding to a density of 0.7. The surf,actants used in this study were as follows: Tergitol• 15-S-9' the 9 mol ethoxylate of a secondary Ctl to C• alcohol sodium lauryl sulfate,õ Bar- quat MB-50 -//Myristyldimethylbenzylammonium chloride. *Union Carbide Corp., New York, N.Y. '•Pel-Freez Biologicals, Inc., Rogers, Arkansas. :i:Marland Breeding Farms, West Milford, N.J. **E. I. du Pont de Nemours & Co., Wilmington, Del. õBDH Chemicals Ltd., Poole, England. //Lonza, Inc., 22-10 Route 208, Fair Lawn, N.J. 07410.