Realizing Precise Molecular Differentiation in Heterogeneous Polyamide Nanofilms Formed via Multi-Stage Interfacial...

Area of Science:

• Materials Science
• Chemical Engineering
• Separation Science

Background:

• High-flux nanofiltration membranes are crucial for sustainable separations, requiring precise control over pore size, uniformity, and surface charge.
• Conventional thin-film composite membranes face limitations due to structural constraints from single-interface interfacial polymerization.

Purpose of the Study:

• To develop a novel method for fabricating nanofiltration membranes with enhanced molecular differentiation capabilities.
• To overcome the structural limitations of conventional membranes by creating a heterogeneous tri-layer polyamide nanofilm.

Main Methods:

• Employed a surfactant-mediated multi-stage interfacial polymerization process.
• Formed a tri-layer polyamide nanofilm with structural heterogeneity by defining three distinct reaction zones and two sub-interfaces.
• Utilized this method to precisely control nanofilm thickness, crosslinking, and mean pore size.

Main Results:

• The resulting nanofilm composite membranes exhibited high methanol permeance (8.3 Lm⁻²h⁻¹bar⁻¹).
• Demonstrated efficient separation of methanol-rich mixed solvents.
• Achieved precise molecular differentiation between similar-sized molecules (azobenzene and neutral red) with exceptionally high selectivity (>480).
• The selectivity surpasses that of state-of-the-art organic-solvent-nanofiltration (OSN) membranes.

Conclusions:

• The multi-stage interfacial polymerization strategy enables precise control over membrane structure and separation performance.
• The developed tri-layer nanofilm composite membranes offer superior selectivity and permeance for demanding separation applications.
• This approach provides a scalable fabrication strategy for rationally designing application-specific OSN membranes.