Thermodynamics of Swelling of Polymer, Oligomer and Polymer-Oligomer Particles. Preparation and Application of Monodisperse Polymer Particles.

Abstract

The treatment of the equilibrium distribution in various polymer-monomer or polymer-mixed solvent systems has most often been based upon the classical Flory-Huggins lattice theory and the extension of this theory by Morton to include the interfacial energy. Further developments of these theories have included the swelling of polymer particles with mixtures of different monomers, systems in which the continuous phase (water in the case of aqueous dispersions) is present in the monomer and polymer phases, and the swelling of oligomer and oligomer-polymer particles. Ugelstad et al. have shown experimentally and theoretically that oligomer particles and oligomerpolymer particles in aqueous dispersions are capable of absorbing monomer to an extent that are orders of magnitude higher than for pure polymer particles. This has led to development of emulsion polymerization procedures which allow preparation of highly monosized large particles in the range of 1–50 μm in diameter. Such particles have up to now found industrial application in liquid chromatography. The particles are furthermore used as standards for blood cell counters. Hydrophilic monosized particles prepared by the new methods are utilized in different immunoassays where they have been found to possess advantageous properties. The monodisperse particles have also founded the basis for the preparation of monosized magnetizable microspheres which have been applied for cell separation.