Suspension Polymerization of Hydrophilic Monomers

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The PI proposes to study hydrophilic (water swellable) microparticle production by suspension polymerization. Such polymer particles have many practical uses including: (1) in chromatographic separations of small or large molecular weight solutes; (2) as ion-exchange resins; (3) as filling materials in packed bed reactors; (4) as releasing agents for antifouling paints in marine science; (5) as carriers for enzyme immobilization; (6) as releasing agents for drugs in pharamaceuticals; and (7) as catalysts in reaction engineering. Structural and geometric characteristics of the microparticles affect their usability in all cases. In suspension polymerization, reaction takes place in an organic monomer phase which is suspended in an inorganic phase; usually water. The product solid polymer precipitates out and contains small amounts (10%) of unreacted monomer. The desired products have controlled: particle size distribution, shape, pore size distribution, molecular weight distribution and molecular weight between crosslinks. In this research the PI plans to do kinetic modelling of batch suspension polymerizations of hydrophilic monomers. Specifically, the work will include the following activities: i. development of the kinetic models applicable to the copolymerization/crosslinking reaction of a hydrophilic monomer with a crosslinking agent, both before and after the gelation point and until vitrification; ii. determination of the molecular weight distribution of the product before the gelation point as a function of the kinetic constants of the reactions and the feed ratio of the monomers; iii. development of the models for reaction engineering in suspension polymerization in batch reactors; iv. determination of the critical parameters that affect the particle size distribution in this type of suspension polymerizations; v. conduct experiments of suspension polymerizations with 2- hydroxyethyl methacrylate (HEMA) and ethylene glycol dimethacrylate (EGDMA) as a crosslinking agent and determination on- or off-line of the particle and molecular weight distributions; and vi. comparison of the predictions of the system equations with experimental results for EGDMA/HEMA batch suspension polymerizations.