2010 TRI/PRINCETON CONFERENCE 253 that modifi cation of nanoparticles with hexylamine enhanced the extraction of linalyl acetate due to hydrophobic interactions (Figure 1a). Release of fragrances in aqueous medium from these modifi ed and unmodifi ed PAA nano- particles were tested at various pH values. In the case of modifi ed as well as unmodifi ed nanoparticles, release of the attribute was more pronounced in the neutral and alkaline pH range than in the acidic range due to better swelling of nanoparticles (Figure 1b). Similarly, the performance of poly(acrylamide) nanoparticles in extraction and release of vanillin fl avor was also studied (4). Similar to the cosmetic attributes, nanoparticles can also be very effective for controlled delivery of other hydrocarbon actives including drugs. The potential of the polyacryl- amide (PAM) nanogels to scavenge amitriptyline, an antidepressant, from aqueous dis- persion was found to be marked (Figure 2). Nanogel particles modifi ed with hexyl and carboxylic acid groups showed enhanced binding to the drug due to ionic exchange com- bined with hydrophobic interactions. Similar studies can be undertaken for applications in cosmetic technology by using actives such a fragrance molecules. HYBRID POLYMERS Hybrid polymers with both hydrophilic and hydrophobic characteristics when dissolved in a solvent can form coiled structures in such a way that the functional groups that are compatible with the solvent protrude outwards and those that are incompatible are Figure 1. (a) Extraction of linalyl acetate by poly(acrylic acid) and hexylamine modifi ed poly(acrylic acid) nanoparticles. (b) Release of linalyl acetate by poly(acrylic acid) nanoparticles and hexylamine modifi ed poly(acrylic acid) nanoparticles as the function of pH of the dispersion medium.

JOURNAL OF COSMETIC SCIENCE 254 packed to form nanodomains, which are either hydrophilic or hydrophobic depending on the nature of the solvent. Ability of the hydrophobically modifi ed hydrophilic polymers to from oleophilic nanodomains can be utilized for the encapsulation and release of or- ganic sensory attributes (16). The potential use of hybrid polymers for formulation of cosmetic products is illustrated in Figure 3. It shows that in polar solvents the hybrid polymers can form hydrophobic domains, where hydrophobic attributes can be incorporated and released as desired. Hybrid silicones are also useful in cosmetic industry not only due to their selective hydro- phobic/oleophobic character but also due to their structure they can be used as agents to Figure 3. Use of a hybrid polymer for encapsulation of cosmetic attributes. Figure 2. Drug binding ability of PAM and modifi ed PAM as a function of residual drug concentration.