SYNTHETIC HAIR CONDITIONING POLYMERS 25 were prepared from all 96 polymers in DOE-1. Hair tresses were treated with these sham- poo formulations and evaluated by the automated wet combing method. Corresponding wet combing work values are listed in Table III. For reference, hair tresses treated with control shampoo formulations containing PQ-67 typically showed wet combing work values of 1,500 N-mm ± 50 N-mm. For several poly- mers from this DOE, low wet combing work values were measured, suggesting very effec- tive conditioning performance. If the force required for combing was too high, hair breakage occurred as noted for many of the polymers containing QMA (Table III). Most of the positive samples (low wet combing work) observed in the library occurred where the polymers were prepared with APTAC. All APTAC-containing reaction mixtures prepared with 5.0 or more wt% BA were turbid (except sample A1), suggesting that BA is not a favorable non- polar monomer for hair conditioning applications at these levels of incorporation since clear shampoo formulations were preferred. All APTAC-containing polymers that showed wet combing work values less than 1,900 N-mm had been prepared with DMAEMA or without the amine monomer polymers prepared with APTAC and DMAEA showed higher wet combing work values. This result suggests that DMAEMA as a comonomer in addition to APTAC generally enables greater conditioning effi ciency than polymers prepared with APTAC and DMAEA, although both monomers have similar amine moieties. In DOE-2, four polymer libraries were prepared using the same monomers and composi- tions as those in DOE-1, except LMA replaced BA as the hydrophobic monomer. Sham- poo formulations were prepared with polymers from DOE-2, and hair tresses were treated with these shampoo formulations and evaluated by the automated wet combing method. For several polymers from DOE-2, low wet combing work values were measured, sug- gesting very effective conditioning performance of these polymers. Similar to the result from the DOE-1, most of the higher-performing polymers were observed where polymers were prepared with APTAC. Among nine APTAC-containing polymers that enabled Scheme 2. Outline of the experimental path to the identifi cation of high-performance conditioning polymer candidates.

JOURNAL OF COSMETIC SCIENCE 26 good combability (wet combing work 2,000 N-mm), four polymers contained LMA as the hydrophobic monomer. However, reaction mixtures for these four LMA-containing polymers were turbid, suggesting a low likelihood of obtaining clear shampoo formulations. Similar to the results from DOE-1, DOE-2 did not identify any polymers prepared with a hydrophobic monomer that would satisfy both application targets: a clear shampoo formulation and good combability. Surprisingly, the presence of hydrophobic comonomer in synthetic cationic polymers in the ranges explored in this study did not appear to show distinct benefi ts for hair care applications, and, therefore, nonpolar monomers were elim- inated from further study. Two libraries were prepared for DOE-3. In the fi rst library, APTAC was selected as the only quat monomer, and only DMAEMA and AAm were used as additional co- monomers. Five high-performing polymers from this library enabled good combabil- ity (wet combing work 2,000 N-mm), with four exhibiting excellent subjective wet feel. In the second DOE-3 library, polymers were again synthesized with APTAC as the quat monomer, with DMAAm and AAm. Many polymers from this library en- abled good combability (wet combing work 2,000 N-mm), and, for almost all of them, an excellent subjective wet feel score (0 or 1). However, most shampoo formu- lations prepared with these polymers were cloudy or hazy, and, in many of them, particles or oily droplets were observed. Only one polymer gave a clear to slightly hazy shampoo formulation, with excellent combability (wet combing work value 671 N-mm) Table III Example Polymer Compositions and Wet-Combing Work for DOE-1 with BA as the Nonpolar Monomer Sample Quat amount DMAEA amount DMAEMA amount AAm amount BA amount Wet combing work APTAC Wet combing work QMA A1 0.95 0 0 0 0.05 2,918 2,482 A2 0.65 0.07 0 0.23 0.05 2,489 Breaka A3 0.95 0.05 0 0 0 7,729 Break A4 0.731 0.244 0 0 0.025 2,020 2,506 A5 0.7 0 0.3 0 0 1,678 3,143 A6 0.65 0.07 0 0.23 0.05 3,558 4,084 A7 0.86 0 0.09 0 0.05 3,925 Break A8 0.7 0 0 0.3 0 1,867 2,824 B1 0.95 0 0 0.025 0.025 3,989 Break B2 0.65 0 0.05 0.3 0 3,709 Break B3 0.65 0 0 0.3 0.05 2,738 Break B4 0.675 0 0.15 0.15 0.025 2,298 Break B5 0.86 0 0 0.09 0.05 1,802 Break B6 0.875 0 0 0.125 0 1,620 Break B7 0.65 0 0.24 0.06 0.05 1,780 2,571 B8 0.742 0 0.129 0.129 0 1,445 Break C1 0.7 0 0 0.25 0.05 3,112 3,553 C2 0.65 0.15 0 0.15 0.05 1,993 3,013 C3 0.65 0.3 0 0 0.05 2,753 Break C4 0.731 0 0 0.244 0.025 3,614 Break C5 0.75 0 0.05 0.2 0 1,613 Break C6 0.65 0.3 0 0.05 0 2029 Break C7 0.65 0 0.15 0.2 0 1,458 Break C8 0.65 0 0.2 0.15 0 1,317 Break a Hair pulled to the point of breaking.