| Nanoscale polymer latexes can be conveniently produced with microemulsion polymerization. These latexes are potentially useful for the coating of microporous materials or in biological applications where the high surface area to volume ratio give desirable diffusive or adhesive properties. However, commercial use of the microemulsion polymerization process has been limited because the final latex is typically dilute in polymer and the final polymer morphology is difficult to control. In this dissertation, these two limitations are overcome by using a multiple addition polymerization process to produce high concentration polymer latexes, and by using a controlled living radical polymerization method to control the polymer chain molecular weight and polydispersity.; In the multiple addition polymerization monomer is added semicontinuously during the polymerization of a microemulsion to produce a final latex solution higher in polymer content using the same amount of initial surfactant. The mechanisms of this process are investigated using an analysis of the polymerization kinetics. The results show, that in the case of n-hexyl methacrylate polymerization, radicals initiated prior to a given monomer addition do not polymerize the added monomer, but instead the added monomer forms new particles. The end result is a polymer dispersion with properties similar to those of an ordinary microemulsion polymerization but with a lower surfactant to polymer ratio.; In controlled living radical polymerization an additive is used to control chain architecture and molecular weight during free radical polymerization. A number of different controlled living radical polymerization techniques have been developed, but one of the more versatile techniques is that of reversible addition fragmentation transfer polymerization (RAFT). In this dissertation, RAFT was used in the microemulsion polymerization of n-hexyl methacrylate to form a polymer of low polydispersity and controlled molecular weight. Kinetic measurements combined with molecular weight analysis confirm that the polymerization proceeded by a controlled living mechanism. Subsequent analysis of the polymerization mechanism through modeling demonstrates the limitations of this approach. |
