340 JOURNAL OF COSMETIC SCIENCE Figure 2. Photomicrograph of a 1% suspension ofdimethicone and 0.5% titanium dioxide in a 1% aqueous solution of the polyquaternium-24/amylose complex (magnified 75x). Table III Prototype Skin Lotion Formulation Employing Polyquaternium-24/Amylose Complex a Dimethicone (Amerchol) 5.00% PQ-24/amylose complex b 91.50% Hydroxylated milk glycerides (Amerchol) 2.00% Glycerin (Mallinckrodt) 0.50% Methyl gluceth-10 (Amerchol) 0.50% Titanium dioxide (Aldrich) 0.50% Preservative c q.s. • Procedure: Disperse micronized titanium dioxide into previously prepared pQ-24/amylose complex at room temperature, followed by dispersion of the dimethicone oil into the complex. Add molten hydroxylated milk glycerides (previously melted in a 45øC oven prior to use). Stir 15 minutes, add glycerin and methyl gluceth-10, and stir for an additional 15 minutes. Add preservative and stir for one hour. b Complex comprises approximately 0.9% Quatrisoft and 0.2% amylose. c DMDM hydantoin at 0.40% or diazolidinyl urea at 1%.

POLYQUATERNIUM-24/AMYLOSE COMPLEX 341 6OOO 5000 4000 3000 2000 1000 Viscosity Vs. Week •:i:!'i."!' '!'!" i :'• •:'•'!•:" •...•.i!:'..., ! ! •'•-i • • • i • • •i"i•.i'i .• - '-• •': 0 I 2 4 5 6 Week •Room Temp. Oven Figure 3. Stability of individual formulations preserved with DMDM hydantoin at room temperature and 45øC. 6OO0 •. 5000 •' 4000 ,_zj, 3000 8 2000 lOOO Viscosity Vs. Week JILl 0 I 2 4 5 6 Week Room Temp Oven Figure 4. Stability of individual formulations preserved with diazolidinyl urea at room temperature and 45øC. more pronounced in the oven-accelerated samples. However, none of the samples showed any indications of creaming, and in fact, after this initial drop, the viscosity stabilized. We attribute the initial viscosity drop to a possible rearrangement of the polyquater- nium-24/amylose complex brought on by the temperature of the oven. Once the for- mulations stabilized to their environmental temperatures, they remained stable for the extent of the test. CONCLUSIONS Although the use of traditional emulsifiers brings many attributes to the science of cosmetic chemistry, one cannot overlook potential detrimental effects and possible ir- ritancy upon application. In this paper, the idea of surfactant-free formulations has been presented using a unique complex formed by non-covalent crosslinking of a hydropho- bically modified, water-soluble cationic cellulose ether, polyquaternium-24, with amy-