96 JOURNAL OF COSMETIC SCIENCE Table II Cloud Points of 1% w Solutions Designation % EO Cloud point (øC) MD*M 74 58 MD*DM 67 57 MD2*/D2M 76 58 MD3*DsM 74 58 MD3*D7M 75 58 MD4*DsM 75 57 the silicone portion of the molecule. Dr. Vick concluded, "A statistical analysis of the cloud point data suggests that fully 98.7% of the data variability is accounted for by the length of the ethylene oxide chains." Our materials vary in molecular weight but not in the amount of polyoxyethylene group. SOLUBILITY The solubility of the DMC materials was measured in polar and non-polar solvents (Table III). The solubility was defined as: soluble (S), clear homogeneous phase dis- persed (D), translucent or cloudy but homogeneous phase insoluble (I), not homoge- neous. All products were soluble in water. As mentioned above in the cloud point discussions, the solubility is related to the amount of polyoxyethylene group. This behavior is similar to that found in ethoxylated alcohols. The average amount of poly- oxyethylene group for all the products studied was similar, about 74%, which makes them soluble in water. All products also showed good solubility in methanol, ethanol, i-propanol, and propylene glycol. Products with higher molecular weight dispersed best in non-polar oils. The larger molecular weight, or longer hydrophobe, seems to contribute to the enhanced nonpolar media solubilization. The large-molecular-weight products will be preferred when for- mulating using an oil base. SURFACE TENSION AND CRITICAL MICELLE CONCENTRATION We also studied cmc (critical micelie concentration) and the surface tension ($) at cmc. Table III Solubility in Various Solvents at 24øC (1% w/5% w) Designation MD*M MD2*D2M MD3*D7M Methanol Soluble/Soluble Soluble/Soluble Soluble/Soluble Ethanol Soluble/Soluble Soluble/Soluble Soluble/Soluble i-Propanol Soluble/Soluble Soluble/Soluble Soluble/Soluble Propylene glycol Soluble/Soluble Soluble/Soluble Soluble/Soluble Water Soluble/Soluble Soluble/Soluble Soluble/Soluble Mineral oil Insoluble/Insoluble Dispersible/Dispersible Dispersible/Dispersible Mineral spirits Insoluble/Insoluble Dispersible/Dispersible Dispersible/Dispersible Silicone oil, 350 cps Insoluble/Insoluble Insoluble/Insoluble Dispersible/Dispersible

DIMETHICONE COPOLYOL 97 The data shows that the lower limit for surface tension for compounds of this type is 20 dynes/cm 2 (Table IV). This compares with typical values and is known to be caused by the low surface energy of the methyl groups in the flexible silicon backbone (1,6). The lack of significant differences in cmc is not very surprising since the hydrophobe- lipophile content is balanced by EMW considerations. The results can also be implied by the cloud point results, which do not vary much either. SPREADING Spreading area was studied relative to water on polyethylene films. Siloxane surfactants are well known for their wetting and spreading properties. These properties make them ideal for use in textiles, coatings, and agricultural adjuvants. For example, spreading and wetting properties are directly related to flow in coatings, spread-out areas in cosmetics formulations, and leaf coverage in pesticide formulations. Silicones typically spread better than conventional organic and fiuorocarbon surfactants. We measured the spreading properties for the various DMCs prepared. Our results, shown in Figure 1, indicate that the isomers studied spread slightly better than water. An optimum was observed at MD2*D2M , clearly outperforming the NP-9EO control. However, none of the samples can be considered superspreaders that, for example, would give a relative value of over 40. These materials are too hydrophilic, as shown by their high cloud point, and thus do not contain the needed subphases (or aggregates) that provide the necessary surfactant concentration gradient, and diffusion rate, in the droplet spreading front that drives the spreading. Literature states that the larger the molecule the slower the spread of the droplet front, and thus the slower the spreading (7-9). This is probably related to monomer size hindrance (molar volume) on packing at the sub- strate surface, possibly higher intrinsic viscosity. FOAMING The degree of polymerization seems to have an effect on foam height (Figure 2). Lower- molecular-weight material showed higher initial (flash) foam. However, the foam sta- bility was similar for both lower and higher molecular weight. EMULSIFICATION The results shown above for solubilization indicate that the lower-molecular-weight products will make good emulsifiers in an aqueous-based emulsion. This was found to Table IV Surface Tension and CMC 8 at CMC Designation CMC (mg/L) (dynes/cm 2) MD*DM 3 20 MD2*D2M 4 19 MD3*DsM 6 23 MD3*D7M 5 21 MD4*DsM 14 21