Highly plasticization-resistant Tröger’s base polymer–MOF mixed-matrix membranes for stable gas separation

• Published in: Separation and purification technology 2025-04, Vol.356, p.129854, Article 129854
• Main Authors: Lee, Jieun, Jeon, Seungbae, Ji An, Eun, Gwon Kim, Hyung, Hui Jo, Jin, Han, Nara, Park, Sungmin, Seok Chi, Won
• Format: Article
• Language: English
• Subjects: Gas separation; Metal–organic framework; Mixed-matrix membrane; Plasticization; Tröger’s base polymer
• ISSN: 1383-5866
• DOI: 10.1016/j.seppur.2024.129854

[Display omitted] •Tröger’s base (TB) polymer was synthesized using an electrophilic aromatic substitution.•Metal-organic framework (MOF) nanoparticles were incorporated into the TB polymer matrix, forming mixed-matrix membranes (MMMs).•TB-MOF MMMs show a significant improvement in H2 and CO2 gas permeabilities.•TB-MOF MMMs exhibit no plasticization pressure point up to 750 psi.•Hydrogen bonding between Tröger’s base and MOF increases polymer chain rigidity. The plasticization phenomenon, characterized by polymer chain swelling when exposed to highly soluble gas at high feed pressure, has been a major problem for polymer membranes. To address this, we prepared Tröger’s base (TB) polymer-based metal–organic framework (MOF) mixed-matrix membranes (MMMs), which are highly plasticization-resistant membranes. Three different highly porous MOF nanoparticles (ZIF-8, UiO-66-NH2, and MIL-101(Cr)) were prepared in small particle sizes. The corresponding MMMs were formed with a 30 wt% MOF loading to study the effects of MOF species, particle size, chemical functionality, and MOF–polymer interfacial interaction on gas-transport properties and plasticization behavior. The TB polymer-based MOF MMMs exhibited significantly higher H2 and CO2 permeabilities (fourfold to eightfold) than the TB polymer membrane owing to the porous nature and high gas adsorption capacity of the MOF. Additionally, the TB-based MOF MMMs, particularly the UiO-66-NH2 MMM, displayed exceptional CO2 plasticization resistance. This is attributed to the interfacial interaction of the strong hydrogen bonding between the amine group of the TB polymer and the amino group of UiO-66-NH2, as confirmed by small-angle X-ray scattering characterization. This TB polymer-based MOF MMM approach provides a feasible and effective route for enhancing gas-transport properties and CO2 plasticization resistance to achieve energy-efficient and stable gas separation.