CONVECTIVE DIFFUSION FROM A DISSOLVING POLYMERIC PARTICLE

A comprehensive mathematical model for describing the process of dissolution of a spherical polymeric particle in a convective field is developed. It includes the process of glass transition, reptation of macromolecules, disengagement of these molecules from the gel-liquid interface, and diffusion in the boundary layer surrounding the gel-liquid interface. Different controlling regimes for the dissolution process are identified and quantitatively delineated in this moving boundary problem. Analytical solutions for the estimation of dissolution time for various limiting cases are presented. Key predictions from the model are verified by comparison with preliminary experimental data. A novel feature of a particle-size-independent dissolution of polymeric particles below a critical size brought out by the model is verified experimentally. The findings have pragmatic implications in diverse areas, such as polymerization, drag reduction, and microlithography.