Composite Colloidal Particles Produced by Carbon Dioxide Assisted Microencapsulation

University Of Rochester, Rochester NY

Investigators

Abstract

Microencapsulation is the process of embedding an additive in a colloidal particle. This technology is widely used to provide extended release of entrapped compounds such as drugs or fragrances. However, microencapsulation may be used to produce composite particles with controlled optical, chemical, or physical properties for a wealth of applications. Current microencapsulation technology typically requires organic solvents that are difficult to remove from the polymer. Residual solvent is especially undesirable for food and drug applications where the maximum allowable concentration is very low. We propose to study the transport of additives into colloidal polymer particles dispersed in an emulsion of liquid or supercritical carbon dioxide and water in an effort to reduce or eliminate the need for organic solvents. At elevated pressures, carbon dioxide swells and plasticizes the polymer particles, facilitating mass transport. Surfactants are used to stabilize the emulsion of CO2 and water. The surfactants also adsorb on the surface of the particles to enhance colloidal stability. After depressurization, the polymer particles return to their original size and shape, entrapping the additive. The adsorbed surfactant remains on the surface and thus offers a route to controlling the surface chemistry of the particles. Biodegradable and biocompatible polymer colloids will be impregnated with drugs, chromophores, and luminescent nanoparticles with the aid of CO2, water, and non-toxic surfactants. In addition, we propose to couple CO2 processing with traditional microencapsulation techniques to lower residual solvent content and sterilize polymer particles. The proposed research will provide a flexible, biologically and environmentally friendly route to the production of composite particles used as devices for drug delivery, tracers and indicators for drug discovery and genomics, and other composite colloidal particles useful for catalysis, coatings, and optical materials. To broaden the impact of the proposed research, a computer based instructional module on microencapsulation technology will be developed and incorporated into the course 'Interfacial Engineering' at the University of Rochester with the assistance of a commercial educational software vendor. The software vendor has expressed interest in incorporating the module into their existing software for broader distribution. Undergraduate and graduate students from diverse backgrounds will be recruited to work on the project through existing programs at the University of Rochester.