Thermodynamic mechanism of structural evolution for polyacrylonitrile membranes prepared via non-solvent induced phase separation

doi:10.1016/j.cjche.2025.06.039

Chinese Journal of Chemical Engineering ›› 2025, Vol. 88 ›› Issue (12): 239-255.DOI: 10.1016/j.cjche.2025.06.039

Thermodynamic mechanism of structural evolution for polyacrylonitrile membranes prepared via non-solvent induced phase separation

Chunqi Wang^1,2,3, Zhongyu Fu^1,2,3, Wei Liu^1,2,3, Shuang Liu^1,2,3, Shiling Jia^1,2,3, Qingxin Meng^1,2,3, Huixuan Zhang^1,2,3

1. School of Chemical Engineering, Changchun University of Technology, Changchun 130012, China;
2. Engineering Research Center of Synthetic Resin and Special Fiber, Ministry of Education, Changchun University of Technology, Changchun 130012, China;
3. Carbon Fiber Industry Innovation Center of Jilin Province, Changchun University of Technology, Changchun 130012, China

Received:2025-03-02 Revised:2025-05-08 Accepted:2025-06-11 Online:2025-11-08 Published:2026-02-09
Contact: Zhongyu Fu,E-mail:fuzhongyu@ccut.edu.cn;Huixuan Zhang,E-mail:zhanghx@ccut.edu.cn
Supported by:
We would like to express our great thanks to Jilin Province National Development and Reform Commission(2024C019-1); Changbaishan Laboratory Science and Technology Innovation Project (CBS2025004, CBS2025004-01); Jilin Province Carbon Fiber Industry Innovation Center (2022C002) for the financial support.

Thermodynamic mechanism of structural evolution for polyacrylonitrile membranes prepared via non-solvent induced phase separation

Chunqi Wang^1,2,3, Zhongyu Fu^1,2,3, Wei Liu^1,2,3, Shuang Liu^1,2,3, Shiling Jia^1,2,3, Qingxin Meng^1,2,3, Huixuan Zhang^1,2,3

1. School of Chemical Engineering, Changchun University of Technology, Changchun 130012, China;
2. Engineering Research Center of Synthetic Resin and Special Fiber, Ministry of Education, Changchun University of Technology, Changchun 130012, China;
3. Carbon Fiber Industry Innovation Center of Jilin Province, Changchun University of Technology, Changchun 130012, China

通讯作者: Zhongyu Fu,E-mail:fuzhongyu@ccut.edu.cn;Huixuan Zhang,E-mail:zhanghx@ccut.edu.cn
基金资助:
We would like to express our great thanks to Jilin Province National Development and Reform Commission(2024C019-1); Changbaishan Laboratory Science and Technology Innovation Project (CBS2025004, CBS2025004-01); Jilin Province Carbon Fiber Industry Innovation Center (2022C002) for the financial support.

Abstract

Abstract: Non-solvent induced phase separation (NIPS) is one of the most used methods for the preparation of PAN membranes. Predicting the pattern of change in membrane structures remains a key issue. A binodal line procedure about PAN/solvent/non-solvent was established for it by Flory-Huggins theory. Calculation of non-solvent-polymer interaction parameter (χ₁₃) by the osmotic pressure method combined with the Rudin model and the equilibrium dissolution method. Solvent-polymer interaction parameter (χ₂₃) by viscosity method. Then, the solvent-nonsolvent interaction parameter (g₁₂) equation is obtained by combining the modified Flory-Huggins free energy. Finally, the accuracy of the model was verified by cloud points experiments and membrane structures. It was found that when mixed non-solvents were used, the binodal line moved to 100% of the added component. Changes in membrane structure coincide with changes in phase diagrams when changing solvent and non-solvent species and temperature. Based on the combination of experiment and theory we obtained the maximum water flux of membranes was increased to 2217.47 L·m^-2·h^-1·bar^-1 with the addition of additives PEG and SiO₂ with DMF/PAN/H₂O system. The average permeate flux over 0.75 h reached 387.12 L·m^-2·h^-1·bar^-1 (1 bar = 0.1 MPa) with 82% flux recovery. The hexadecane oil-in-water emulsion have confirmed that the membranes showed prominently high retention rate achieved 99% for oil.

Key words: Polyacrylonitrile membrane, Phase separation, Thermodynamic

摘要： Non-solvent induced phase separation (NIPS) is one of the most used methods for the preparation of PAN membranes. Predicting the pattern of change in membrane structures remains a key issue. A binodal line procedure about PAN/solvent/non-solvent was established for it by Flory-Huggins theory. Calculation of non-solvent-polymer interaction parameter (χ₁₃) by the osmotic pressure method combined with the Rudin model and the equilibrium dissolution method. Solvent-polymer interaction parameter (χ₂₃) by viscosity method. Then, the solvent-nonsolvent interaction parameter (g₁₂) equation is obtained by combining the modified Flory-Huggins free energy. Finally, the accuracy of the model was verified by cloud points experiments and membrane structures. It was found that when mixed non-solvents were used, the binodal line moved to 100% of the added component. Changes in membrane structure coincide with changes in phase diagrams when changing solvent and non-solvent species and temperature. Based on the combination of experiment and theory we obtained the maximum water flux of membranes was increased to 2217.47 L·m^-2·h^-1·bar^-1 with the addition of additives PEG and SiO₂ with DMF/PAN/H₂O system. The average permeate flux over 0.75 h reached 387.12 L·m^-2·h^-1·bar^-1 (1 bar = 0.1 MPa) with 82% flux recovery. The hexadecane oil-in-water emulsion have confirmed that the membranes showed prominently high retention rate achieved 99% for oil.

关键词: Polyacrylonitrile membrane, Phase separation, Thermodynamic

Chunqi Wang, Zhongyu Fu, Wei Liu, Shuang Liu, Shiling Jia, Qingxin Meng, Huixuan Zhang. Thermodynamic mechanism of structural evolution for polyacrylonitrile membranes prepared via non-solvent induced phase separation[J]. Chinese Journal of Chemical Engineering, 2025, 88(12): 239-255.

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Thermodynamic mechanism of structural evolution for polyacrylonitrile membranes prepared via non-solvent induced phase separation

Thermodynamic mechanism of structural evolution for polyacrylonitrile membranes prepared via non-solvent induced phase separation

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