Fuente: Journal of applied polymer Lugar: RESEARCH ARTICLE The IL@TpDT composite was synthesized by impregnating TpDT-COF with ionic liquid (IL). IL modification enhanced CO2 affinity and reduced pore size, improving CO2 adsorption selectivity. The porous structure further boosted gas adsorption and diffusion, simultaneously increasing permeability and selectivity to overcome the trade-off effect. This method strengthens nanomaterial-polyimide interfacial interactions for practical gas separation.

ABSTRACT
In this work, a novel fluorinated diamine monomer, 3-methoxy-4-fluoro-4,4′-diaminotriphenylamine (FMBDA), was synthesized through molecular design. And then copolymerized with 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and 4,4′-oxydianiline (ODA) to prepare fluorinated polyimide (FPI). Subsequently, the covalent organic framework (TpDT) was modified with the imidazolium ionic liquid [Emim][Tf2N] (IL) via solution impregnation, and the resulting IL@TpDT was doped into FPI to prepare IL@TpDT/FPI mixed matrix membranes (MMMs) with varying mass fractions. The obtained MMMs exhibited excellent thermal properties (T
g > 295°C, T
10% > 528°C), commendable mechanical properties (tensile strength > 81.08 MPa), and outstanding hydrophobic properties (contact angle > 86.90°). IL modification endows TpDT with improved CO2 affinity and a smaller pore size, thereby enhancing the membrane material CO2 adsorption selectivity. Simultaneously, the porous structure of the nanocomposite boosts gas adsorption and diffusion, further improving gas separation performance. At an IL@TpDT loading of 3 wt%, CO2 and O2 permeability increased by 222% and 123%, respectively, compared to the FPI matrix membrane. The CO2/N2 and O2/N2 separation factors rose to 27.27 and 4.81, respectively.