JOURNAL OF COSMETIC SCIENCE 18 they are present (surfactant type and charge, surfactant blend ratio and concentration, salt levels, dilution levels and rate of dilution, wash water hardness, etc.) (4–8). They function via phase separation, or coacervation, during dilution on rinsing, depositing the cationic polymer on the negatively charged keratin (9). These polymers also have a role as deposition aids for insoluble benefi t agents such as silicone polymers (10,11), where the factors as outlined earlier also are important to their function (2,12). Two naturally derived cationic polymers used extensively in the conditioning market today include cationic hydroxyethyl cellulose [UCARE™ polymers Polyquaternium (PQ-10)] (13) and cationic guar (guar hydroxypropyltrimonium chloride). The per- formance and mechanism of action of the conditioning polymers have been reviewed (see, for example, references 14–17). Ma ny synthetic cationic conditioning polymers have also been made via free-radical polymerization from vinyl monomers including acrylates and acrylamides (18–29). Examples of commercially used synthetic cationic conditioning polymers are shown in Table I. The cationic (“quat”) monomers used include [(3-acrylamidopropyl)]-trimeth- ylammonium chloride (APTAC), diallyldimethylammonium chloride (DADMAC), 2-(N,N,N-trimethylammonium)ethyl methacrylate chloride (QMA), and 2-(N,N,N-tri- methylammonium)ethyl acrylate chloride (AETAC). So me of the high-performing naturally derived conditioning polymers such as PQ-10 are expensive to produce [cationic guar, another naturally derived polymer, is low in cost but suffers from deposition build-up issues (30)]. Evaluation of several experi- mental and commercial cationic polymers has identifi ed several issues with some wholly synthetic conditioning polymers including hazy shampoo formulations, the need for antioxidants as stabilizers, and substantial silicone build-up on the hair (3). It was a goal of this preliminary work to identify synthetic polymer compositions that exhibit the conditioning performance of a hydrophobically modifi ed cationic hydroxyethyl cellulose polymer, SOFTCAT™ SL-5 (PQ-67) (13), which in our hands provides both good deposition and comb properties (both greater than PQ-10) (31), at low costs typical of synthetic polymers. To that end, this preliminary study fo- cused on the generation of a broad range of polymer compositions and their rapid initial screening for conditioning performance against a single clear shampoo base. Combinatorial methods have previously been applied to the determination of conditioning Table I Examples of Commercial Conditioning Polymers Quat monomera Polymer (supplier) AAmb Quat/AAmc QMA PQ-11 (BASF) VPd Unknown APTAC Acrylamidopropyltrimonium chloride / acrylamide copolymer (Ciba) Yes ~40/60 DADMAC PQ-6 (Nalco) No 100/0 DADMAC PQ-7 (Nalco) Yes 70/30 DADMAC PQ-6 (Ciba) No 100/0 a QMA: 2-(N,N,N-trimethylammonium)ethyl methacrylate, chloride APTAC: (3-acrylamido)propyl- trimethylammonium chloride, DADMAC: diallyldimethylammonium chloride. b AAm: acrylamide. c Estimated wt/wt. d VP: 1-vinyl-2-pyrrolidinone (used instead of AAm).

SYNTHETIC HAIR CONDITIONING POLYMERS 19 polymer phase behavior and shampoo formulation (32,33). In this initial study, ex- perimental design methods enabled by high throughput combinatorial methods were used in a broad polymer design, synthesis, and focused screening effort that led to the identifi cation of synthetic cationic conditioning polymer candidates that show con- ditioning performance (combability, silicone deposition, wet feel, etc.) similar to or greater than that of PQ-67 in limited and preliminary performance screens. Further work will be needed to understand polymer performance in a wider range of formula- tions and treatment conditions. EXP ERIMENTAL METHODS MAT ERIALS APT AC, AETAC, DADMAC, QMA, 2-(dimethylamino)ethyl acrylate (DMAEA), 2-(dimethylamino)ethyl methacrylate (DMAEMA), acrylamide (AAm), N,N-dimethyl- acrylamide (DMAAm), butyl acrylate (BA), methyl methacrylate (MMA), lauryl acrylate (LA), lauryl methacrylate (LMA), stearyl methacrylate (SMA), tert-butyl hydroperoxide (TBHP), sodium 1-hydroxymethanesulfonate (sodium formaldehyde sulfoxylate, SFS), and citric acid were purchased from Sigma-Aldrich (St. Louis, MO) (see Figure 1 for the structures of the monomers). Surfactants sodium laureth-2 sul- fate (SLES-2 primary anionic surfactant) and disodium cocoamphocarboxyglycinate (amphoteric surfactant) were purchased from Cognis (Cincinnati, OH). Dimethylol- dimethylhydantoin (DMDMH 55 preservative broad-spectrum bactericide) was obtained from Lonza (South Plainfi eld, NJ). Hair care polymers CELLOSIZE™ QP 100MH, UCARE™ JR-400 (PQ-10), UCARE™ LR-30M (PQ-10), UCARE™ JR-30M (PQ-10), and SOFTCAT™ SL-5 (PQ-67) were obtained from the Dow Chemical Company (Midland, MI). Cationic guar was obtained from Rhodia (Houston, TX). The silicone emulsion DC 1664 was purchased from Dow Corning (Midland, MI). Hair tresses (8 h bleached hair) were purchased from International Hair Importers and Products (White Plains, NY). Figure 1. Chemical structures of vinyl monomers used in this study.