Kinetics and Mechanism of Stable Free Radical Miniemulsion Polymerization (SFRMP) and Application to the Preparation of Nanostructured Latex Particles

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Most polymeric materials with special properties have narrow molecular weight distributions (MWDs). In this project the PIs will use a novel free radical initiator system with nitroxide stable radicals that will promote the synthesis of polymers with narrow MWDs. Initial attempts to use this initiator system in emulsion polymerizations were unsuccessful, and problems were traced to large monomer droplets. To overcome these problems, a miniemulsion polymerization technique was developed. Monomer is first dispersed in the form of submicron droplets where nucleation and polymerization occur. Polystyrene latexes with relatively high solids content and with particle sizes of 100 nm were successfully prepared, and narrow MWDs were obtained. An understanding of the kinetics and mechanism of this unique emulsion polymerization process is one of the primary goals of this project. New avenues for the synthesis of latex particles with a variety of covalently bonded functional groups (e. g., carboxyl, amino, epoxy) at the particle surface will be explored. The PIs will also take advantage of the "living" character of polymer chains in an investigation of the preparation of multi-layered colloidal particles with desired surface structures/properties by sequential monomer addition steps. The properties of these materials will be measured and are expected to differ substantially from those being made by conventional polymerization processes.