Simulation of phase separation process in polymeric membranes

The MUFFIN engine (a mean-field method based on Flory-Huggins free energy) was used to simulate the structural formation process of polymer membranes by the nonsolvent-induced phase separation (NIPS) process. Diffusion of solvent and nonsolvent and phase separation behavior were visualized, providing design guidelines for controlling porous membrane structures.

Use Cases Highlights

Evaluation of the NIPS (nonsolvent-induced phase separation) process using mean-field methods
Visualization at nanoscale that is difficult to observe experimentally

Evaluation of the NIPS (nonsolvent-induced phase separation) process using the mean-field method

Time evolution of the NIPS process in a 2D model is shown. A nonsolvent is placed in the upper half, and a polymer/solvent/nonsolvent mixture membrane in the lower half. Over time, the nonsolvent penetrates the membrane, and phase separation progresses as the solvent diffuses.

Time evolution of phase separation in a polymer membrane considering the NIPS process (2D model)

Visualization at the nanoscale that is difficult to observe experimentally

The results of a phase separation simulation using a three-dimensional model are shown. To simulate polymer vitrification, a concentration-dependent mobility was introduced, reproducing structures close to real materials such as the formation of holes on the membrane surface.

Concentration dependence of motion of each component and time evolution of the NIPS process considering polymer vitrification (3D model)

Reference

[1] Simulation of Solvent Evaporation Using DPD
[2] Slurry Coating Process [Courtesy of Toyota Motor Corporation]
[3] https://octa.jp/jp/components/muffin/
[4] Soft Matter,13, 3013, (2017)
[5] J. Membrane Sci., 599, 117826, (2020)
[6] https://unit.aist.go.jp/cd-fmat/ja/c-dmd/ja/freport/contents/fr220118_3-07.pdf
[7] ACS Macro Lett., 9, 1617-1624, (2020)
[8] J. Membrane Sci., 619, 118779, (2021)
[9] J. Chem. Phys., 154, 104903, (2021)
[10] ACS Appl. Mater. Interfaces, (2023) https://doi.org/10.1021/acsami.3c03126

Details of analysis