ORGANOFUNCTIONALIZED SILICONE RESINS niques (34). Hair body may also be increased through alterations in fiber fiber inter- actions. This is most commonly accomplished by the use of polymeric setting lotions, gels, and hair sprays that form rigid joints between contacting fibers. The existence of such joints limits subsequent fiber displacement, increasing the resiliency and structural integrity of the set mass of hair (29). Incorporating conditioning agents into these fixative formulations in attempts to protect the hair usually decreases the efficacy of the volume-enhancing composition. In general, products that provide appreciable conditioning benefits to the hair, such as silicone fluids and quaternary ammonium compounds, do not impart improved body or hair volume (29-30,35). This was found to be the case with the commercial conditioning compositions. The moisturizing formulation, which decreased combing work by 85%, resulted in a reduction in tress volume of 15.4% as compared to the control. The commercial volume-enhancing product was found to provide an increase in hair volume as compared to the moisturizing version (by over 8%) however, the hair treated with this formulation was characterized by a decrease in tress volume of 7% as compared to the shampooed control, as shown in Figure 4. This was not unexpected, based on the reduction in interfiber friction observed with this formulation in the combing studies. The correlation of combing force reduction with corresponding decrease in tress diam- eter was indeed observed with the ester- and polyether-modified silicone resins as well. The results obtained with the alkyl-modified siloxysilicates, on the other hand, were rather surprising and did not fit this trend. It was anticipated that as the alkyl chain 25 20 15 10 5 0 -5 -10 -15 -20 .,:: o { Figure 4. Changes in maximum tress diameter, or hair volume, for hair treated with conditioning formu- lations comprising various siloxysilicate resins • compared to commercially available moisturizing and body-enh•cing conditioning products.

12 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS length increased, the conditioning ability would improve and the tress volume would decrease. In fact, there was no significant difference in combing forces between any of the compounds evaluated, while the resins modified with longer-chain olefin groups pro- vided a volumizing effect to the tresses, effectively improving hair body. It can be seen in Figure 4 that the conditioner base control composition produced a decrease in maximum tress diameter (MTD) of approximately 12%. This percentage reduction in tress diameter is typical for known conditioning agents such as dimethi- cone, amodimethicone, or quats (30,35). The unmodified siloxysilicate resin and the Clo alkyl-modified resin produced comparable reductions in MTD of approximately 10% each, as did the ester-functional material. The composition containing the polyether- modified resin performed slightly better, with a reduction in tress volume of approxi- mately 5%. The C16_18 and C2o_24 materials, on the other hand, were found to increase hair volume by approximately 8% and 21%, respectively. Since most agents that in- crease hair volume (such as organic resins, polymers, or proteins) also increase combing forces, it was noteworthy that the longer-chain alkyl-modified siloxysilicate resins pro- vided an increase in tress diameter while actually reducing combing forces by up to 44% as compared to the shampooed control. In subjective evaluations, panelists rated these tresses as feeling softer and being more manageable than the controls, manageability being defined as the ease of arranging hair in place and its temporary ability to stay in place (36). Thomson eta/. reported on a different type of silicone resin, cationic silsesquioxane or "T" resins, which they found to also increase hair volume (35). These compounds were prepared by hydrolysis of ethylenediamine trialkoxy silane that rendered the resulting silsesquioxane resins water-soluble. The alkylsilanes were found to provide improve- ments in body/volume and manageability for dry hair however, the results of panel tests indicated detrimental to at best equivalent performance in combing, tangling, feel, and weight of both wet and dry hair treated with these compounds. The alkyl-modified siloxysilicate resins of the current investigation were unique in that they resulted in significant increases in tress volume (up to 21% for the C20_24-modified material) while also providing a reduction in combing forces and imparting a soft feel to the hair. The dependence on volume increase with increasing alkyl chain length is noteworthy, and the trend is expected to continue with the C24_26 and C3o + materials. In order to evaluate this theory, a new conditioning formulation is under development that will support incorporation of these particular resins. Also planned is synthesis of comparable resins holding the alkyl chain length constant while varying the degree of substitution, and subsequent combing and volume measurements utilizing these compounds. SET RETENTION The results of the curl retention study are presented in Figure 5. It can be seen that under the test conditions the water-set control maintained approximately 50% of its original curl after 24 hr. The alkyl-modified resins were not efficacious in this application, with the Clo and C16_18-treated tresses each losing approximately 60% of their curl. The C2o_24-treated tress performed slightly worse, with a 76% reduction in curl during the same time period. The tresses treated with the ester functional resin were found to be comparable to the alkyl-modified resins, with approximately 65% of the curl lost over