Swelling of Polymer-Oligomer Particles

A quantitative study of the swelling capacity of polymer-oligomer particles, and the rate of transport of slightly water soluble compound 1, e.g. chlorobenzene, from bulk phase to the particles has been carried out. A much higher swelling capacity was attained when compound 1 was subdivided (before it was added to the swelling experiments) than when it was added as a bulk at the same experimental conditions. It is shown that the increased swelling capacity when compound 1 is subdivided may lead to a much higher value of the equilibrium swelling with compound 1. In previous studies and at the beginning of this work, one was not sufficiently aware of the importance of the kinetics of swelling where the rate is much faster when compound 1 is ·subdivided, such that it depends on the number and radius of the particles Nprp while when compound 1 is added as a bulk phase, the rate dependend on the number and radius of droplets, Nara· It was possible to swell polymer-oligomer particles of ~ 2.5μm with v/v rates of polymer to oligomer of 2:1 up to 40 μm in a relatively short time when compound 1 was subdivided. When compound 1 was added as a bulk, the size reached with the same polymer-oligomer particles was ~ 16μm. The dependence of the rate and swelling capacity on such factors as the type and amount of oligomer used and the nature of emulsifier, was found to agree well with theoretical considerations. The speed of stirrer was also found to be an important factor affecting the rate of transport of compound 1 to the particles. Bidisperse emulsions were made by competitive swelling, and. the radii of _two kinds of particles agree experimentally well with theoretical calculations. Diffusion of coinpound 1 from polymeroligomer particles swollen with compound 1 to polymer-oligomer particles was very fast. The compound 1 is distributed on a large number of particles with a very high total surface