An Overview of the Theoretical Models Used to Predict Transport of Small Molecules through Polymer Membranes

The interactions between polymer membranes and organic solvents, gases or vapors, water, and aqueous salt solutions have been extensively studied for almost half a century; nevertheless, complete understanding of the transport mechanism (sorption, diffusion, and permeation) at the molecular level is still far from satisfactory [1–10]. The interest that exists in the study of transport of small molecules through polymer membranes is due to the fact that a number of important practical applications depend wholly or in part on such phenomena. These include protective coatings such as paints and varnishes [11–14], electronic devices and cable materials [15–18], packaging materials for foods and vegetables [19–24], selective barriers for the separation of gaseous and liquid mixtures [25–29], biomedical devices [30–34], etc.