Rigorous Models for Vapor Diffusion in Polymers with Immobilization and Chemical Potential Gradients

• DOI: 10.1021/acs.jpcb.4c03888
• Publication Date: 2024-09-13T07:06:06Z
• Authors: Brandon L. Foley; Sylvie Aubry; Maxwell Murialdo; Elizabeth A. Glascoe
• Keywords: Capillary condensation

Two key phenomena─immobilization and concentration-dependent mixing free energies─simultaneously alter the sorption thermodynamics diffusion of vapors in materials. This interrelation is leveraged to fit a unified model simultaneously capturing both dynamics equilibrium isotherms. transport incorporates quasi-equilibrated immobilization reactions considers Fick's law rigorously terms chemical potential gradients rather than concentration gradients. Five material case studies are discussed with varying characteristics, including fillers that provide sites for surface sorption, pores capillary condensation, apparent clustering or pooling at high vapor concentrations. Each study illustrates intrinsic diffusivity constant, while effective changes predictably because changing energies mixing.