Advanced Polymer Materials for Membrane Separation

Dear Colleagues,

Membrane technology has been widely applied in solutions to many issues that humans are currently facing regarding energy resources, water resources, the environment, health, et al. Polymers, as significant raw materials, play a key role in membrane separation processes, in which high-efficiency separation with low energy consumption is desirable. In the field of Advanced Polymer Materials for Membrane Separation, researchers are exploring various innovative approaches to enhance membrane performance, particularly in applications such as gas separation, water treatment, organic solvent separation, and ion exchange/transport in fuel cells and lithium–sulfur batteries. Here is a summary of some key points:

1. Two-Dimensional Polymer Nanosheets: Since the discovery of single-layer graphene in 2004, two-dimensional inorganic nanosheets have been considered ideal membrane materials due to their ultrathin atomic thickness and fascinating physicochemical properties. However, the non-porous nature of these inorganic nanosheets has limited their potential for higher flux. Recently, two-dimensional polymer nanosheets, originating from the regular and periodic covalent connection of building units in a 2D plane, have emerged as promising candidates for preparing ultrafast and highly selective membranes. Their inherent tunable and ordered pore structure, their lightweight characteristics, and high specific surface area make them attractive for membrane separation applications.
2. Mixed Matrix Membranes (MMMs): By hybridizing mechanically robust polymer matrices with molecularly selective inorganic fillers, such as Metal–Organic Frameworks (MOFs), MMMs can improve the separation efficiency of pure polymer membranes. MOFs demonstrate great potential due to their tunable characteristics, but challenges remain, including filler–matrix incompatibility, particle agglomeration, insufficient operational stability, and limited scalability.
3. Polymer Metal–Organic Framework (polyMOF) Nanoparticles: Recently, polyMOFs, consisting of amorphous and linear polymer ligands coordinated with metal ions, have gained attention as a unique class of hybrid materials that combine the features of both polymers and MOFs. These materials have shown excellent potential for tailoring the physicochemical properties of existing MOFs for efficient CO₂ separation.
4. Organic Solvent Separation Membranes: There is a growing interest in membrane-based organic solvent separation, and membranes that exhibit high permeance, high selectivity, and long-term stability against solvents are sought after. Significant progress has been made by integrating established polymeric membranes with emerging materials such as porous polymers, MOFs, and two-dimensional (2D) materials. However, most current polymers remain challenging in regards to the balance between resistance and process, key characteristics which activate advanced polymer materials to fabricate high-performance membranes for solvent separation.
5. Porous Organic Polymers (POPs): POPs are an emerging class of porous materials constructed from lightweight elements like H, B, C, N, O, and Si. The microporosity of these materials provides rigid pore architectures and opportunities for pore engineering. POPs are thermally and chemically more stable than organic–inorganic hybrid porous materials and have demonstrated promising potential in various applications due to their permanent porosity and ease of functionalization.

These research advancements indicate that advanced polymer materials have broad application prospects in membrane separation technology, especially in improving separation efficiency, reducing energy consumption, and minimizing environmental impact. With continuous advancements in material science and manufacturing technologies, it is anticipated that more innovative membrane materials will be developed to meet industrial and environmental separation needs in the future.

Dr. Zhisheng Fu
Dr. Chuanjie Fang
Guest Editors

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• polymer
• membrane separation technology
• energy conservation
• water resource
• environment protection
• human health
• gas separation
• water treatment
• organic solvent separation
• ion exchange/transport
• two-dimensional polymer nanosheets
• mixed matrix membranes
• polymer metal–organic framework nanoparticles
• organic solvent separation membranes
• porous organic polymers