REDUCING FACIAL WRINKLE SIZE USING POLYMERS 133 Here, we will show that the two polymers studied cause shrinkage in cosmetic fi lms, leading to a consumer-perceivable reduction in size of features such as pores and wrinkles on the underlying skin substrate. MATERIALS AND METHODS PRODUCT FORMULATIONS We used model emulsion formulations with 5 w% hydrogenated polyisobutene (Luvitol Lite BASF Corporation, Florham Park, NJ) as the oil phase and 1 w% of a phenoxyethanol/ethyl- hexylglycerin preservative (Euxyl PE 9010 Schülke & Mayr GmbH, Fairfi eld, NJ) (Table I). The pH was adjusted with sodium hydroxide (AMRESCO LLC, Solon, OH). The polymers used were an acrylate/methacrylamide copolymer (“AMC”, Luviset One BASF Corporation), PVP (Luviskol K90 BASF Corporation) and carbomer (Rheocare C Plus BASF Corporation). For the PVP and placebo formulations, carbomer was predispersed in water and neutral- ized before all other ingredients were added, after which the product was homogenized using a Silverson homogenizer. For the other formulations, all ingredients were combined and homogenized until uniform. GLASS TRANSITION TEMPERATURE MEASUREMENTS To obtain solid polymer samples, 5% neutralized polymer solutions were prepared and 10 g of the solution dried in an aluminum pan with a diameter of approximately 3 cm. The conditioning of the resulting polymer fi lms at different humidities (50%, 75%, and 90% relative humidity (RH)) was carried out with the open aluminum differential scanning calorimeter (DSC) pans in three different desiccators. The desired RH in the desiccators was adjusted using different salt solutions: calcium nitrate for 50% RH, sodium chloride for 75% RH, and barium chloride for 90% RH. The samples were conditioned until a constant weight of the aluminum pans was reached. The difference in weight (start vs. equilibrium state) was analyzed to obtain the water uptake of the polymer fi lms. In the next step, the pans were closed and the glass transition was investigated using a TA Instruments Q2000 differential scanning calorimeter (TA Instruments, New Castle, DL). Tg was determined as the midpoint temperature, where half of the specifi c heat increment occurred. Table I Model Emulsio n Formulations Product # 4% AMC 2% AMC PVP Placebo Deionized water 89.7 w% 91.7 91.9 93.4 Hydrogenated polyisobutene 5.0 5.0 5.0 5.0 Phenoxyethanol/ethylhexylglycerin mixture 1.0 1.0 1.0 1.0 Acrylate/methacrylamide copolymer (AMC) 4.0 2.0 PVP 1.5 Carbomer 0.5 0.5 Sodium hydroxide 0.3 0.3 0.1 0.1

JOURNAL OF COSMETIC SCIENCE 134 CLINICAL STUDY PROTOCOL Thirty two healthy female subjects were recruited for this study. They were 35–65 years old, were graded with a score of 2–4 on the Skin Aging Atlas (16) for crow’s feet wrinkles, and considered themselves to have a loss of elasticity in the skin. The study started on July 20, 2015 and concluded on July 24, 2015. All subjects executed an Informed Con- sent Form before the study started. The principles of Good Clinical Practice, as defi ned by the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use, were followed except for the requirement that investigational products should be manufactured, handled, and stored in accordance with applicable Good Manufacturing Practice, which is not a requirement for cosmetic products. The study protocol was reviewed and approved by our Institutional Review Board on June 18, 2015. There were no adverse events encountered and no protocol amendments or deviations took place. About 0.4 g of each test product was applied evenly to the left or right side of the face in a randomized manner. The test was double blind and subjects served as their own refer- ence. Four test products were applied over the 2 day duration of the study. For 3 days before the study, subjects cleansed the face twice a day with PURPOSE® Gentle Cleansing Wash (Valeant Consumer Products, Montreal, Canada). On study days, subjects acclimated for 20 min, after which facial images were recorded and skin mechanical measurements were taken. Two test products were applied in a split-face fashion after the baseline measure- ments, after which additional images and mechanical measurements were taken. MECHANICAL MEASUREMENTS The mechanical properties of skin were assessed using a Ballistometer (Dia-stron, Broomall, PA) and a Cutometer® SEM 575 (Courage & Khazaka, Cologne, Germany). The Ballis- tometer determines skin elasticity by monitoring the bouncing of a stylus on the skin surface. The Cutometer measures the deformation of skin produced by suction for a brief time period (17). Although the elasticity measurement principle is different, the two instruments often show the same trends. The Cutometer generates a range of mechanical properties that relate to skin elasticity, deformation under stress, and recovery. We have focused on the R0 and R3 parameters, which relate to the maximum amplitude of deformation of the skin initially and after three cycles of deformation and recovery, respectively, indicating skin fi rmness after repeated deformation (18). In both cases, lower values of the parameters indicate less viscous de- formation and therefore fi rmer, more elastic skin. The Ballistometer measures the coeffi cient of restitution (CoR), which is based on the stylus bounce height relative to the starting height, a measure of the skin elasticity. Higher values indicate the skin is more elastic and fi rmer (19). Hence, if skin becomes fi rmer over the course of the study, we expect R0 and R3 to decline and the CoR to increase. Cutometer measurements were taken on the left and right cheekbones with four curves recorded on each area for each subject and an average calculated. Ballistometer data were obtained on the left and right temples, with three measurements taken at each location and an average calculated.