THE LIFE TIME OF A DISSOLVING POLYMERIC PARTICLE

The life time of a dissolving polymeric particle in a hydrodynamic field is predicted by building up a model that includes the phenomenon of reptation of the macromolecules, disengagement of these molecules from the gel-liquid interface and also diffusion in the boundary layer surrounding the gel-liquid interface. The model predictions have been verified through some preliminary experiments. A striking experimental observation is that below a critical particle size, the dissolution time does not depend on the particle dimension, a finding that is in sharp contrast to the dissolution of ordinary low molecular weight systems. The minimum time for dissolution in the particle size independent region is shown to satisfy the prediction emanating from scaling theories. The implications of the findings in engineering practice have been discussed.