Development of<i> In Situ</i> Cooling Natural Rubber Film

Abstract

Natural rubber latex (NRL) with the deproteinized process was interesting for cosmetic and transdermal drug delivery systems because of its notable characteristics. The purpose of this study was to develop in situ cooling films from deproteinized natural rubber latex (DNRL). Menthol, camphor, and volatile oils were added into DNRL emulsions for cooling effect and pain relief. The pH, rheological properties, particle size, and zeta potential of emulsions were examined. Then, the time of film-formation, morphology, and mechanical properties of the cooling NRL films were evaluated. The resultant emulsions revealed that their pH was about 5.7 - 6.3. The viscosity was in the range of 1000 – 3000 cps and indicated the pseudoplastic flow. The increasing amount of olive oil reduced the particle size and increased the negatively zeta potential of those emulsions. The film formation time of specimens was about 4.5 - 6.5 mins. The cooling films demonstrated smoothness and homogeneity. The presence of olive oil increased the softness of films. The increasing of oil volume increased the elasticity; however, it decreased the ductility of the films. This in situ cooling DNRL film was also effective forward for the development of a transdermal drug delivery system.