Design of Binary Polymeric Coatings for Minimizing the Residual Solvent, Part I: Experimentation

Abstract

Several binary polymeric coatings of poly(styrene)–tetrahydrofuran have been dried under quiescent drying conditions. Coatings are made using four different solutions of polymer having 5.01, 9.75, 10.06, and 15.14 wt% poly(styrene) initially. Experiments were performed for several different thicknesses for each polymer solution. Residual solvent remaining was lowest in the thicker coating. Results show that the thicker coating should be applied once rather than layer by layer to minimize the remaining residual solvent. The next layer is applied after complete drying of the previous layer. This practice should continue until the desired thickness is obtained. For instance, coatings of initial thickness 1010 µ m and final thickness 61 µm have residual solvent which is lower than the residual solvent in dried coatings of nearly the same final thicknesses using the layer-by-layer technique.