Molecular dynamics study of competing hydrogen bonding interactions in multicomponent diffusion in polyurethanes

Mark J. Varady, Craig K. Knox, Jerry B. Cabalo, Stefan A. Bringuier, Thomas P. Pearl, Robert H. Lambeth, Brent A. Mantooth

Index: 10.1016/j.polymer.2018.02.039

Full Text: HTML

Abstract

Understanding multicomponent diffusion in polymers on the molecular-scale could lead to optimization of many practical processes. One important example is the removal of a toxic chemical (penetrant) from polyurethanes, which serve as the binder in many coatings technologies. This work is an equilibrium molecular dynamics (MD) study to characterize the molecular-scale hydrogen bonding (H-bonding) interactions in ternary penetrant, solvent, and polyurethane systems, and how these H-bonds influence the corresponding diffusivities. Homomorphic series of penetrant and solvent species in which molecular size and shape are kept constant while varying polarity or number of H-bonding sites are used to study the influence of hydrogen bond probability and strength on diffusivity. It is found that H-bonding between all species in the ternary mixture as well as penetrant-solvent collisions play a role in determining penetrant diffusivity. The findings provide insight into solvent selection criteria to increase the diffusivity of H-bonding penetrants that are absorbed in polyurethanes for extraction and decontamination applications.