Emulsion polymerization involves polymerization in a heterogeneous system consisting of an aqueous phase and a dispersed oil phase. The initiator, initially located in the aqueous phase, diffuses into the oily phase where growth and termination occur. These systems exhibit characteristically high reaction rates and a high degree of polymerization. The product is comprised of collidal polymer paticles in a stable suspension, often referred to as latex, dispersed in the aqueous phase. Some products such as synthetic rubbers, molding plastics and trade resins must be recovered from the latex before final formulation and use. Other products such as surface coatings and adhesives can utilize the polymeric materials in latex form. The general thrust of this work is to develop a deeper and more fundamental understanding of the complex phenomena comprising emulsion polymerization. Four projects are planned: 1. Copolymerization studies in a reactor system comprising a tubular prereactor followed by a series of two continuous stirred tank reactors (CSTRs). The focus of the work is measurement of reaction rate, particle size distibution, composition of the copolymer formed in each reactor, and molecular weights. The work will involve studies of grafting reaction kinetics, morphology of the latex particles from copolymerization reactions and the use of functional monomers that are water soluble. 2. Determination of the distribution of free radicals in latex particles. The focus of the work is on utilizing the concept of a nonuniform radical distribution to model grafting reactions aimed at studying the development of particle morphology. 3. Studying particle concentration and size distribution which influences rheology and, in many cases, application performance. The work will include studies of particle number control for semi-batch systems. 4. Use of functional monomers with carboxyl groups to help stabilize particles and improve application performance. The work should elucidate, for example, the compositional parameters that characterize the polymer molecules which are formed in the aqueous and oily phases. The results should assist in the developments of new products and processes in which grafting reactions, particle characteristics, and polymer molecular composition variables are important.
