Hydrogen-bonded organic frameworks in solution enables continuous and high-crystalline membranes

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Engineering

Background:

• Hydrogen-Bonded Organic Frameworks (HOFs) are emerging porous materials with limited research on their solution behavior.
• Understanding the solution state of HOFs is crucial for developing new fabrication methods.

Purpose of the Study:

• To investigate the solution state of HOFs.
• To explore the fabrication of continuous HOF membranes from solution.
• To evaluate the gas separation performance of these membranes.

Main Methods:

• Dispersing HOFs in solvents and characterizing the resulting solutions using Cryo-electron microscopy, 3D electron diffraction, 1D and 2D-Nuclear Magnetic Resonance (NMR), and zeta potential analysis.
• Fabricating continuous HOF membranes via a solution-casting approach.
• Testing the gas separation performance of HOF membranes for C3H6/C3H8 mixtures.

Main Results:

• HOFs fragment into small particles in solvents while retaining their assemblies.
• HOF-based colloidal solutions exhibit distinct intermolecular interactions and aggregation behavior compared to isolated molecular solutions.
• Continuous HOF membranes with high crystallinity and porosity were successfully fabricated.
• HOF-BTB@AAO membranes demonstrated high C3H6 permeance and excellent C3H6/C3H8 separation performance (SF=14).

Conclusions:

• HOFs possess unique solution processability, enabling the fabrication of continuous membranes.
• These HOF membranes offer a green, low-cost, and efficient technology for gas separation.
• Potential applications include petroleum cracking and purification processes.