Interactions between methanol/toluene binary mixtures and an organic solvent nanofiltration PIM-1 membrane

In this work, a molecular scale study of the interactions between a polymer with intrinsic microporosity (PIM-1) membrane and toluene, methanol and their mixtures was performed by means of molecular dynamics simulations. From the radial distribution functions we highlight specific interactions between the hydroxyl group of methanol and the aromatic ring of toluene as well as with the PIM-1 membrane. Moreover, the presence of nitrogen atoms on the PIM-1 backbone makes it possible the formation of hydrogen bonds like interaction (close contact of 2.5 angstrom) between the methanol molecules and the PIM1 membrane, thus leading to interfacial anchoring of methanol at the polymer surface and moving toluene molecules away from the surface. However some toluene molecules are located around 3.5 angstrom due to p-stacking interaction between the aromatic rings of the PIM-1 membrane and those of the confined TOL molecules. At short range, the confined methanol molecules interact with each other like their bulk-phase counterparts whereas long range correlations highlight a existence of confined methanol aggregates. The specific interactions between toluene, methanol and the PIM-1 membrane result in a linear increase of the membrane swelling with the mole fraction of toluene in the binary mixtures. (c) 2022 Elsevier B.V. All rights reserved.

Automated summary

A molecular dynamics simulation was used to study the interactions between a polymer membrane and toluene, methanol, and their mixtures. The results showed specific interactions between methanol and the polymer membrane, as well as between toluene and the polymer membrane. These interactions resulted in membrane swelling.