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Layer-by-layer Synthesis and Transfer of Freestanding Conjugated Microporous Polymer Nanomembranes
Published on: December 15, 2015
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Microporous Polymer Membranes: Molecular Stents Enhanced Solvent-Accessibility for Organic Solvent Transport
Shuang Guo1, Chuanjie Fang1, Jiaqi Li1
1MOE Key Laboratory of Macromolecular Synthesis and Functionalization, MOE Engineering Research Center of Membrane and Water Treatment Technology, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou, 310027, China.
Summary
Researchers developed a new microporous polyimide (PI-TB-NDI) membrane for organic solvent nanofiltration. Introducing ortho-methyl groups enlarged pores, significantly boosting ethanol permeability while maintaining selectivity.
Area of Science:
- Polymer Science
- Materials Chemistry
- Chemical Engineering
Background:
- Microporous polymer membranes are crucial for organic solvent separations.
- High solvent permeability is often limited by sub-0.4 nm pores from tight molecular packing.
- Achieving high permeability without sacrificing selectivity remains a challenge.
Purpose of the Study:
- To synthesize a novel microporous polyimide (PI-TB-NDI) for organic solvent nanofiltration.
- To enhance solvent accessibility and permeability by controlling pore size distribution.
- To develop a design strategy for tailored free volume in membranes.
Main Methods:
- Synthesis of a polyimide incorporating naphthalenediimide (NDI) and Tröger's base (TB) units.
- Introduction of ortho-methyl groups onto the TB unit to create steric hindrance.
- Fabrication and performance evaluation of the resulting polymer membranes for nanofiltration.
Main Results:
- The synthesized PI-TB-NDI polymer exhibited high intrinsic free volume.
- Ortho-methyl group introduction enlarged sub-0.4 nm pores to 0.6-0.7 nm, creating solvent-accessible sub-nanochannels.
- Ethanol permeability increased 2-8 times compared to state-of-the-art membranes with similar selectivity.
Conclusions:
- The ortho-methyl group strategy effectively suppresses detrimental tight packing while maintaining molecular interactions.
- The developed membranes offer superior solvent permeability for organic solvent nanofiltration.
- This work provides a new design approach for advanced microporous membranes without post-treatments.
