SYNTHETIC HAIR CONDITIONING POLYMERS 21 chromatography. The following conditions were used: (i) column: TSKgel Alpha-M (7.8 mm × 30 cm, 13μ) (Tosoh Biosciences, King of Prussia, PA), ii) mobile phase: 0.5 M CH3COOH + 0.1 M NaNO3 in deionized water, (iii) fl ow rate: 0.55 mL/min temperature: 25°C detector: refrac- tive index, and (iv) sample concen tration: 1 mg/mL in the mobile phase. SHAMPOO FORMULATIONS C ationic polymers synth esized in this work were used in the preparation of shampoo for- mulations. The composition of the standard test shampoo formulation is shown in Table II. Shampoo samples were pr epared both on bench scale and on 6 mL scale using the ScPPR. A typical bench scale procedure is outlined as follows: (i) add surfactant base to tared jar with stirrer (ii) slowly add polymer solution with stirring stir at high speed until well mixed (~30 min) (iii) add 10 wt% citri c acid solution to formulation, stir for 10 min (iv) add DMDMH 55. Mix thoroughly for 10 min and (v) stir for 45 min , fi rst applying heat (water bath, 60°C), and then allow temperature to decline to 23°C (vi) add water to a total of 100 wt%, stir for 15 min and (vii) check pH (shou ld be ~5.5). In a typical 6-mL scale procedure conducted on the ScPPR, eight dried (in vacuo) poly- mers were placed into eight vials. Water was added into each vial to give a set of eight 2.0 wt% polymer dispersions that were stirred fi rst at ambient temperature for 30 min, and then at 65°C for 30 min. The desired outcome was complete dissolution of the polymers and formation of clear polymer solutions. A master batch of surfactants was prepared from SLES-2 (73.7 wt%) and cocoamphocarboxyglycinate, disodium salt (8.4 wt%) in water (17.9 wt%). This masterbatch mixture was stirred at ambient temperature for 30 min to give a clear surfactant solution. Aliquots (4.13 g each) of this surfactant solu- tion were placed into each of the eight ScPPR glass inserts, and either water control (0.75 mL no polymer) or one of the 2% polymer solutions (0.75 g) prepared earlier was added into the inserts. These eight mixtures were capped, heated to 65°C, and stirred at 1,400 rpm for 20 min. The mixtures were cooled, citric acid was then added to each solution, and the resulting mixtures were stirred at ambient temperature at 1,400 rpm for 10 min. The temperature set point was then reduced to 15°C, and the mixtures were stirred at 1,400 RPM for 15 min. DMDMH 55 preservative was then added into each insert, and the mixtures were stirred at 1,400 RPM for 2 min. The inserts with the resulting formu- lations were then removed from the ScPPR and sealed. Table II Composition of a Standard Shampoo Formulation Ingredient Active (wt%) Amount (wt%) Polymer 2 15.00a SLES-2b 25.7% active, as received 60.78 Cocoamphocarboxyglycinate, disodium saltc 38.5% active, as received 6.92 Citric acid 10 2.2 DMDMH 55 – 0.4 Water – 14.7 Total 100 a 0.30 wt% polymer solids in fi nal formulation. b Primary anionic surfactant. c Amphoteric surfactant.

JOURNAL OF COSMETIC SCIENCE 22 WET COMBING WORK The objecti ve wet combabilit y was measured by pulling a small comb through a wet hair tress and using a tensile tester to measure total combing work done (force exerted vs. displacement) (34,35). Hair tresses (mass ~5 g) were prewashed fi rst to remove any contamination and ensure tress uniformity, then washed with a shampoo base (0.5 g) without conditioning polymer, and rinsed at constant temperature followed by measurement of wet combing work (control). The same tress was subsequently washed again with the shampoo containing the conditioning polymer candidate, rinsed, and the wet combing work measured again. The wet hair tresses were attached to a multichannel parallel tensile tester, referred to here as the automated tensile tester. A small plastic comb was pulled through each hair tress at a pull- ing speed of 40 mm/min over a path length of 160 mm, and the force required to comb the hair was reported versus comb displacement. Conditioning effi cacy is expressed as the work (N-mm) required to comb the hair tress as determined by the area below the force (mea- sured in N) versus displacement curve and reported as the automated wet combing work. SUBJECTIVE WET FEEL A subjec tive and comparative rating of the wet feel of the tresses after shampooing was used in the evaluation of many polymer libraries. Hair tresses were rated on a scale of 0 through 5, with 0 being the best feel and fi ve being the worst. SILICONE DEPOSITION Silicone -containing shampoo formulations were prepared using the same procedure as described for shampoo formulations without silicone, except that the polymer level was reduced to 0.25 wt%, and two additional components were included in the formulation: ethylene glycol distearate and silicone emulsion DC 1664 (50% active), each at 2.0 wt% in the formulation. The amount of silicone deposited on the hair after treatment with silicone-containing shampoo formulations was then determined (3) the hair tress (~5 g) was washed with a silicone-containing shampoo formulation (0.5 g) and rinsed at con- stant temperature. The hair was then extracted with a 1:1 (v/v) mixture of methyl butyl ketone and toluene. Atomic absorption spectroscopy was used to measure the silicone content, which is reported as the mass of silicone (μg) / mass of hair (g). RESULTS AND DISCUSSION METHOD VALIDATION Before scre ening candidate po lymers, it was necessary to validate the automated tensile tester method for determining wet combing work for each conditioning polymer candi- date and to determine whether this method gives results comparable to standard bench- top methods, including a correct ranking of conditioning performances for known conditioning polymers. The following set of commercial polymers, with the following previously determined ranking of conditioning effi ciencies from highest to lowest (based on least to most work on combing as well as extensive historical panel testing), was used: