80 JOURNAL OF COSMETIC SCIENCE demonstrate that as the ratio of anionic to cationic monomer in the polyampholyte is increased, a larger area of "clear • polymer-surfactant-pH combinations exist. Implications for substrate interactions With the isoelectric point of hair being reported at pH 3.4 - 4.5 I• and the 'surface" pH of skin being reported to range between pH 4 - 614, a complex deposition mechanism can be postulated. Formulations containing polyampholytes and anionic surfactants can be made at near neutral pH (pH of 6-7) which are aesthetically desirable. As the formulation is applied to the substrate of choice the actions of dilution and/or contact with an acidic surface can lead to the formation of an insoluble polyampholyte-anionic surfactant complex which enhances deposition onto the substrate surface. Thus providing a method for "targeting" deposition. Conclusions The complex forming behavior of ampholytic polymers with anionic surfactants was studied and contrasted with cationic polymers. The ability to form clear solutions with ampholytic polymers was found to be a function of polymer composition, the molar cationic charge to anionic surfactant ratio and solution pH. Cationic polymer solutions with anionic surfactants formed clear solutions relatively independent of pH. A mechanism is postulated wherein the variable pH characteristic of polyampholyte-anionic surfactant complexes can be used to target deposition of polymers onto substrates. Figure 1: Claseic Callonlc Polymer - ArtIonic Surflctant Phase Diagram ARImllC Surfactant (lOg Scale) Figure 2: Polyampholyte Net Charge as a Function of pH 6. 5 References: 1) J. Faucher and E. Goddard, J. of Colloid & Interface $ci., 55 313-318 (1976) 2) A. Sykes and P. Hammes, Drug & Cosmetic Industry, 2 (1980) 3) S. Chen and C. Vaughan, US Patent 5,609,862 (1997) 4) J. Boothe, L. Morse and W. Klein, US Patent 4,764,365 (1994) 5) D. Cohen, E. Hitchcock and S. Pohl, US Patent 5,393,305 (1995) 6) G. Matz, A. Melby, S. Chen and C. Vaughan, EP 522,756 (1993) 7) T. Dhaliwal, US Patent 5,591,425 (1997) 8) A. Darkwa and A. Villanueva, US Patent 5,679,327 (1997) 9) C. Dubief and D. Cauwet, US Patent 5,650,383 (1997) 10) Hollenberg and Matzik, DE 4421031 (1995) 11) E. Goddard and R. Harman, J. Am. Oil Chem. Soc., 54 561 (1977) 12) 13) 14) Monomer Key: AA: Acrylic Acid Am: Acrylamide MA: Methyl Acrylate DMDAAC: Dimethyl Diallyl Ammonium Chloride MAPTAC: Methacrylamidopropyl Trimethyl Ammonium Chloride E. Goddard, J. Faucher, R. Scott and M. Turney, J. Soc. Cosmetic Chem., 26 539 (1975) C. Robbins, Chemical and Physical Behavior of Human Hair 2 • ed., Springer-Verlag, NY (1988) G. Yosipovitch and H. Maibach, Cosmetics & Toiletries, 111 101 (1996)

PREPRINTS OF THE 1998 ANNUAL SCIENTIFIC MEETING 81 PH EFFECT ON THE PHASE BEHAVIOR OF DODECYLTRIMETHYLAMMONIUM BROMIDE AND POLYVINYLAMINE SOLUTIONS Stacey V. Maggio and Robert Y. Lochhead University of Southern Mississippi, Hattiesburg, MS 39406 Introduction Polymer - surfactant interactions play an important role in industrial fields such as pharmaceuticals, cosmetics, food preparations, and detergents. This wide array of applications has sparked an interest in the fundamental research of polymer-surfactant interactions. Although there has been much work conducted in this area, there is still a need for fundamental research to gain a better understanding of these interactions. The overall goal of the proposed research is to study a model system by tailoring the charge density and hydrophobic content ratio of a cationic polyelectrolyte, polyvinylamine, in order to induce unique liquid crystalline phase behavior resulting from the interactions with a cationic surfactant, dodecyltrimethylammonium bromide. The ability to control the counterbalance between attractive and repulsive forces may allow for the precise control of desired phase behavior, which could offer significant advantages in the industrial applications of polymer-surfactant pairs. Experimental Polyvinylamine was synthesized by acid hydrolysis of free radically polymerized N-vinylformamide. Following the synthesis, phase diagrams were constructed by preparing samples of varying polymer and surfactant concentrations. After an equilibrium period the samples were observed using polarizing light microscopy to check for birefringence. Surface tension measurements were made using the Wilhemy Plate method on a Kruss K12 Tensiometer equipped with a Dosimat. Results and Discussion Phase diagrams were constructed to observe if hydrophobic interactions between the unmodified PVAm and the DTAB resulted in any unique phase behavior. Figure I shows the binary phase diagram for DTAB and PVAm at pH 5. As observed in the data, for DTAB alone the hexagonal phase does not appear until a surfactant concentration of 50 wt%. However, in the presence of PVAm the hexagonal phase appears at a surfactant concentration of 20 wt% with 40 wt% PVAm, which is much lower than in the surfactant alone. The binary phase diagram for DTAB and PVAm at pH 7 is shown in Figure 2. At pH 7, just as at pH 5, the hexagonal phase for DTAB alone shows up near 50 wt%, while in the presence of DTAB it appears at 20 wt% DTAB with only 30 wt% PVAm. At the increased pH the hexagonal phase is appearing at the same lower surfactant concentration, but with less polymer concentration. At pH 10 the hexagonal phase for DTAB alone also shows up near 50 wt%, while in the presence of PVAm the hexagonal phase appears at 10 wt%DTAB with 30 wt% PVAm. At even higher pH the hexagonal phase appears at even lower surfactant concentrations. For comparison with the pH5 and 7 systems, the hexagonal phase at 20 wt% DTAB at pH I0 show up with only 20 wt% PVAm, which is even lower in polymer concentration. DTAB and P•y(vi•lamine) Binary Phase Diagram ß pH5 4O "1 'H 'H I - IIO•al• 30 "1 "1 'H ,i ,i ,H&I ß 1 ,I "1 "1 q ,14,14,14 . Figure I DTAB a•l P•y(vinylaml•e) Binary Phase Diagram •40 q q I. ISOtrOl• . 30 1 '1 '1 ,,i • ,,i *N&i *N _ , . , _ . . . . . . , o m • •o ,,o •o Weight Percent DTAB Figure 2