Diffusion Process during Drying to Cause the Skin Formation in Polymer Solutions

Abstract

We discuss the diffusion process of polymers in polymer solution undergoing evaporation of the solvent at the free surface, and obtain a diffusion-type equation with a moving boundary condition in one dimension. Taking into account the effect of gelation (or solidification) of the solution, we carry out numerical simulations of the one-dimensional model. Based on the numerical results, we present a detailed description of the condition related to the “skin” formation due to the surface gelation. Furthermore, we also show that the drying dynamics of polymer solutions is strongly related to a gelation, which causes a great increase of diffusion coefficient of polymers.