Shape-Selective Molecular Separations Enabled by Rigid and Interconnected Confinements Engineered in Conjugated...

Area of Science:

• Materials Science
• Chemical Engineering
• Polymer Chemistry

Background:

• Separating molecules with similar sizes but different shapes is a significant challenge in chemistry and materials science.
• Existing separation technologies often struggle with high-precision molecular discrimination based on subtle structural differences.

Purpose of the Study:

• To develop advanced conjugated microporous polymer (CMP) membranes for efficient shape-based molecular separation.
• To investigate the relationship between membrane structure, pore characteristics, and separation performance.

Main Methods:

• Preparation of CMP membranes using diffusion-modulated electropolymerization for precise control over pore network.
• Tuning carbazole-based backbones to adjust pore size, connectivity, and confinement properties.
• Characterization of membrane structure and evaluation of separation performance for various molecular systems.

Main Results:

• CMP membranes with narrowly distributed network pores were successfully synthesized, preventing defects and aggregate pores.
• High separation factors (up to 134) were achieved for molecules with linear vs. bulky shapes (≈1000 g mol⁻¹).
• Demonstrated all-liquid phase separation of linear/branched alkane isomers (<100 g mol⁻¹) with high hexane enrichment (63.35 mole%) and superior permeance.

Conclusions:

• Diffusion-modulated electropolymerization offers precise control over CMP membrane fabrication for tailored separation.
• The rigid, interconnected pore structure effectively enforces molecular shape selectivity.
• These CMP membranes represent a significant advancement in high-performance molecular separation, particularly for challenging isomer separations.