JOURNAL OF COSMETIC SCIENCE 44 preserved using sodium benzoate at a pH 5. These formulations exhibited outstanding mildness, foaming, and clarity and also demonstrated thickening at low pH values (Fig- ure 2) that could contribute to product viscosity. Additionally, by employing 100% bio- based PGEs instead of highly ethoxylated sorbitan esters, the renewable carbon content in the formulations was increased dramatically. CATIONIC ETHERS OF PG AND PGEs AS NOVEL CONDITIONING AGENTS FOR SKIN AND HAIR Both PG and PGEs may be substituted with quaternary ammonium groups via reaction with 2,3-epoxypropylalkyldimethylammonium chloride or 3-chloro-2-hydroxypropylal- kyldimethylammonium chloride reagents in aqueous media to yield cationic hydroxypropyl PG ethers (6). The cationic groups may be either hydrophilic or hydrophobic in nature, e.g., trimethylammonium versus C12–C18 alkyldimethylammonium, and combinations of cationic groups may also be employed. Cationic amphiphilic molecules demonstrating surface activity can be achieved by either modifying PG with long chain alkyl (e.g., lauryl Table I Low pH, Mild Cleansing Formulations Based on High HLB PGEs Ingredient (INCI name) Example 2 (wt% active) Example 7 (wt% active) Polyglyceryl-10 oleate 3.60 3.60 Polyglyceryl-10 laurate 1.00 1.00 Coco-betaine 5.63 – Sodium lauroamphohydroxypropylsulfonate – 5.63 Sodium cocoyl glutamate 4.05 – Sodium methyl 2-sulfolaurate (and) disodium 2-sulfolaurate – 4.05 Sodium benzoate 0.5 0.5 Sodium chloride 4.00 – Citric acid Q.S. to pH 4.5 Q.S. to pH 4.9 Water Q.S. to 100 wt% Q.S. to 100 wt% Figure 2. Zero-shear viscosity as a function of pH for the formulations in Table I. pH adjusted via addition of concentrated citric acid solution.

NEW COSMETIC INGREDIENTS FROM POLYGLYCEROL 45 or stearyl) quaternary ammonium groups or by modifying PGEs with trimethylam- monium groups. The properties of cationic PG and PGE derivatives can be tuned by controlling multiple synthetic variables, i.e., PG degree of polymerization (DP), PGE acyl chain length, PGE degree of acyl substitution, degree of cationic substitution, and the ratio of hydrophilic/amphiphilic cationic groups, enabling the synthesis of ingredi- ents with performance targeted to specifi c applications. Figure 3 shows schematic exam- ples of the design fl exibility afforded by this chemistry. Cationic amphiphilic PGs are particularly well suited for application as ethoxylate-free alternatives to substantive humectants such as lauryl methyl gluceth-10 hydroxypropyl- trimonium chloride (7). The nonionic, hydrophilic character of PG provides similar humectancy, mildness, and formulation compatibility analogous to that of PEG, whereas the cationic quaternary ammonium groups enable substantivity to keratinaceous substrates, i.e., hair and skin, and provide antistatic benefi ts on hair. Cationic amphiphilic PG deriva- tives demonstrate good foaming behavior due to their surface activity and do not negatively impact foam performance in surfactant-based cleansers. These compounds have also shown potential to act as micellar thickeners in surfactant systems, although the viscosity building ability is highly dependent on the exact molecular structure of the derivative (6). MICELLAR THICKENERS DERIVED FROM PG-MODIFIED METHYL GLUCOSIDE OR SORBITAN DIESTERS Although most PG is derived via condensation polymerization of glycerol, PG may also be prepared via base-catalyzed ring-opening polymerization of GC initiated by any substrate bearing an alcohol group (2,8). In contrast to the postpolymerization reactions where functional groups are “reacted to” PG, this addition polymerization route enables PG chains to be “grown from” a variety of hydroxyl functional starting materials. In an effort to synthesize PG-based alternatives to highly ethoxylated micellar thickeners, e.g., PEG-120 methyl glucose dioleate and PEG-150 distearate, GC polymerization ini- tiated by hydrophobic diesters, such as methyl glucose dioleate (MGD) or sorbitan diole- ate, was used to prepare a series of polyglyceryl polyol esters for evaluation as thickeners for surfactant systems, as illustrated by the example in Figure 4. GC and acetylated GC were also copolymerized from MGD in an effort to limit branching in the PG chains by blocking some of the hydroxyl groups where PG branching can occur. Figure 3. Schematic representation depicting synthetic design fl exibility of cationic amphiphilic PG derivatives. LD: laurdimoniumhydroxypropyl TM: hydroxypropyltrimonium PG-10: polyglycerin-10 PG-10-1-O: polyglyceryl-10 oleate.