]. Soc. Co.wnet. Che•n., 22, 83-94 (Feb. 4, 1971) Photochemical Reactions in Presence of Surfactants and Macromolecules H. B. KOSTENBAUDER, Ph.D., M. J. JAWAD, M.S., PO-LAI SUNG, B.S., and G. A. DIGENIS, Ph.D.* Presented May 26-27, 1970, New York City Synopsis--The rates of PHOTOCHEMICAL REACTIONS involving many coloring agents and DRUGS can be markedly influenced by the presence of POLYMERS and micellar SUR- FACTANTS. Such interactions may lead to either increased or decreased stability of the light-absorbing compound or they may introduce new reaction pathways. Such modification of light stability may arise from the presence of reactive functions in the MACROMOLE- CULES, through complexation with macromolecules, or through photoinduced binding of excited-state DYE or drug species to macromolecules. Examples are presented to illustrate the involvement of dyes and drugs in photoreduction, photooxidation, coupled oxidation- reduction, photodimerization, and in triplet-triplet energy transfer reactions, and the manner in which surfactants and macromolecules present in cosmetic formulations might alter such reactions. INTRODUCTION It is not intended that this presentation be an all-inclusive survey of work accomplished in this field, but that it be a selective utilization ot5 appropriate examples to illustrate the potential influence o15 macromole- cules and surfactants on photochemical reactions. A review o15 the basic concepts o15 photochemistry appeared in this Journal relatively recently (1) and familiarity with these concepts is assumed. The complexity of photochemical reactions and the relatively small volume of published work with respect to photochemical reactions in * College of Pharmacy, University of Kentucky, Lexington, Ky. 40506. 83

84 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS presence o[ macromolecules and surfactants makes it difficult to predict what effects might be encountered in a particular system however, a con- sideration o[ reactions which have been studied permits illustration o[ some of the effects which might be encountered. EXPERIMENTAL Procedures for photochemical studies are essentially those described in previous work (2). The visible light source employed was unfiltered light from a 300-watt tungsten lamp mounted in a slide projector the ultraviolet source employed in the menadione study was a Pen Ray mer- cury lamp • emitting radiation of primarily 253.7 nm. Dyes were com- mercial materials used without further purification. Suroeactants were commercial materials except for the sodium decyl suloeate which was syn- thesized and purified as previously described (3). All malachite green studies were conducted in 0.1M acetate buffer at pH 5.0, indigo carmine studies were performed in 0.05M phosphate buffer at pH 7.4, and mena- dione and Clomacran studies were conducted in distilled water. Spectra were recorded on a Cary 15 spectrophotometer and photobleaching was determined by loss of absorbance at the appropriate wavelength maxi- mum. Methods employed for determination of ground state binding of dyes or drugs to surface active agents were the equilibrium dialysis (4-6) and solubility methods (4) described previously. RESULTS AND DISCUSSION Photoreduction Macromolecules such as polymers and miceliar surfactants may in- crease, retard, or have no effect on the rate of photoreduction of dyes. Alteration in rate of photoreduction usually involves a binding or com- plexing interaction of the dye with the macromolecule. Oster and coworkers have provided a wealth of data on the enhance- ment of photoreduction of dyes by polymers such as polyvinylpyrrolidone (PVP) and polymethacrylic acid (PMA). A number of triphenylmethane dyes such as Crystal Violet, Ethyl Violet, malachite green, pararosaniline, basic fuchsin, and Victoria Blue 4R are not photoreduced in the presence of a mild reducing agent such as ascorbic acid in aqueous solution, but when PMA is added to the dye-ascorbic acid solution photoreduction of Arthur H. Thomas, Philadclphia, Pa.