CONVECTIVE DIFFUSION FROM A DISSOLVING POLYMERIC PARTICLE

A comprehensive mathematical model for describing the process of disso lution of a spherical polymeric particle in a convective field is deve loped. It includes the process of glass transition, reptation of macro molecules, disengagement of these molecules from the gel-liquid interf ace, and diffusion in the boundary layer surrounding the gel-liquid in terface. Different controlling regimes for the dissolution process are identified and quantitatively delineated in this moving boundary prob lem. Analytical solutions for the estimation of dissolution time for v arious limiting cases are presented. Key predictions from the model ar e verified by comparison with preliminary experimental data. A novel f eature of a particle-size-independent dissolution of polymeric particl es below a critical size brought out by the model is verified experime ntally. The findings have pragmatic implications in diverse areas, suc h as polymerization, drag reduction, and microlithography.