The isolation of pure olefins and paraffins from their mixtures is a complex and energy-demanding process due to their nearly identical physical characteristics, which pose significant challenges for their separation. Membrane-based methods provide a more sustainable and energy-efficient solution, offering high selectivity and lower operational costs than conventional, energy-intensive methods such as cryogenic distillation. The present study explores the dispersion of the aqueous-media synthesized zeolitic imidazolate frameworks (ZIF-8, ZIF-67, and ZIF-8-67) into a Tröger's base polymer of intrinsic microporosity (PIM-EA(Me2)-TB) to form mixed matrix membranes (MMMs), which are investigated for the efficient separation of C3H6/C3H8, as well as other light gases. At 20 wt % ZIF loading, the MMMs demonstrate a significant performance enhancement when compared to the neat membrane. The incorporation of ZIFs increases the ideal selectivity for propene/propane separation, with ZIF-67 achieving the highest value (17). Notably, the ZIF-8-67-based MMM shows a comparable C3H6/C3H8 selectivity to that of the ZIF-67-based MMMs, but with the smallest reduction in propene permeability, from about 4000 to 2000 Barrer, among all formulations. The ZIF/PIM-EA(Me2)-TB MMMs, particularly the bimetallic-containing one, showed a promising propene/propane selective performance and surpassed the 2020 C3H6/C3H8 upper bound by hitting 15. These findings suggest that ZIF/PIM-EA(Me2)-TB MMMs provide an effective approach for challenging gas separations and offer a promising solution for industrial applications in gas purification and separation processes. A good fit of the C3H6 and C3H8 permeation data with the modified Maxwell model suggests matrix rigidification, which translates into antiplasticization for these highly soluble gases.

In this work, we report a series of Matrimid (R) 9725 based mixed matrix membranes (MMMs) containing 10 wt% and 20 wt% of highly microporous hypercrosslinked triptycene PIMs (HCP-PIMs) fillers. The latter were used either in their pristine hydrocarbon form, or functionalized with nitro, amino, or sulfonic groups. Single gas timelag measurements show that the combination of the lowly permeable polymeric matrix and the highly porous fillers leads to an enhancement of gas selectivity (up to 29 % for CO2/CH4) and, depending on the filler, to an up to twofold increased permeability for CO2. The selectivity increase seems influenced by the nature of the functional groups, while the permeability by the filler's high surface areas. Specifically, an enhancement of the permeability is observed across all MMMs, with the best results achieved with the hydrocarbon and the nitro functionalized HPC fillers (PIM-Trip-H and PIM-Trip-NO2), which show an up to twofold increment of the permeability compared to the pure Matrimid, accompanied by a further improvement of the selectivity for gas pairs such as CO2/CH4 and O2/N2. Thermal studies show that permeability increases upon heating for all MMMs, while the selectivity decreases for gas pairs involving condensable gases such as CO2. For instance, from 25 degrees C to 45 degrees C the permeability of CH4 increases up to about 300 % and that of CO2 only between 25 % and 50 %. Finally, the entropic and energetic contributions to diffusion selectivity are analyzed, providing insight into the varying influences of diffusivity and selectivity for different gases.

The development of high-performance polymeric membranes is critical for advancing energy-efficient CO2 separation technologies. While machine learning (ML) has emerged as a powerful tool for predicting gas permeability and accelerating polymer discovery, most existing approaches rely on limited experimental descriptors and act as black boxes, offering little physical insight or reliability assessment. Here, we use ML as a molecular microscope to construct a physically informed and interpretable framework for predicting gas-transport properties in polymeric membranes for CO2 capture. By integrating structural fingerprints, physicochemical descriptors, and operational variables such as temperature and pressure, the framework moves beyond the typical black-box paradigm toward physically interpretable structure-property relationships. The approach combines data imputation through Multiple Imputation by Chained Equations (MICE), regression modeling with ensemble algorithms, and rigorous applicability-domain analysis to ensure predictive reliability. Feature-importance and explainability analyses reveal the molecular signatures that control gas transport—rigid, branched, and moderately polar architectures that balance free volume and solubility. This interpretive capability transforms ML into an analytical tool for rational polymer design, bridging predictive accuracy with chemical understanding and providing quantitative guidance for the next generation of CO2-selective membranes.

In this work, we report a series of hyper-cross-linked sulfonated polymers, structurally related to PIMs, as highly efficient and versatile catalysts for biodiesel production. By tuning monomer composition to increase aromatic content, we generate porous polymers with tailored surface areas and porosity, which are thoroughly characterized and assessed for CO2/N2 separation. These catalysts promote both Fischer esterification of free fatty acids and transesterification of triglyceride oils derived from the same fatty acids, achieving over 95% conversion to fatty acid methyl esters (FAME) in 24 h or less under diverse conditions. Remarkably, by using a variety of oils, high activity is maintained even with reduced catalyst and methanol loadings, demonstrating intrinsic efficiency and robustness. The polymers prove to be fully scalable and recyclable, retaining performance over multiple cycles and efficiently converting waste cooking sunflower oil with comparable yields to pure edible oils. This work establishes a direct structure-property-performance relationship, linking polymer architecture and porosity to catalytic activity, and provides a versatile, sustainable platform for next-generation porous catalysts in biodiesel production and broader chemical transformations.

This study discloses the role of framework topology and pore chemical environment in governing CO 2 adsorption, dynamics and transport properties in the fumarate-based Zr-MOFs, MOF-801 and MIP-203, and in their PIM-1 based mixed matrix membranes.

Polyimides (PIs) are a significant class of high-performance polymers due to their exceptional thermal, mechanical, and chemical stability. Their combination with polymers of intrinsic microporosity (PIMs) provides access to materials with structural robustness coupled with permanent microporosity. Progress in this area is frequently constrained by the limited availability of difficult-to-prepare and structurally complex dianhydrides. Building on our recent work on [2.2]-paracyclophane (PCP)-based PIMs for gas sorption, we report a series of PCP-polyimide PIMs synthesized from PCP-derived dianhydrides and amino-PCP monomers. The preparation of these dianhydrides enabled a systematic investigation of the monomer structure and connectivity. Two polymer families were obtained: PCP-PIs incorporating pseudo-para and pseudo-meta-PCP units and an ethanoanthracene analogue and a corresponding series of 4,4'-(hexafluoroisopropylidene)-diphthalic anhydride (6FDA)-based PCP polymers. Gas sorption measurements show very good CO2/N2 separation performance with the highest selectivity observed for the meta-PCP-ethanoanthracene system (PCP-PI4, ∼40). Polymers derived entirely from PCP-based dianhydride and bisaniline units in a pseudo-meta configuration also display a capability for strong separation of gases (CO2/N2 = 32.5), underscoring the role of monomer design in tuning the separation properties. Extensive structural and morphological characterizations were performed using multinuclear solid-state NMR, Fourier-transform infrared spectroscopy (FT-IR), wide-angle X-ray diffraction (WAXD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX), while the thermal stability was determined by thermogravimetric analysis (TGA).

Previously, it has been reported that amine-PIM-1, a polymer of intrinsic microporosity obtained by reduction of nitrile groups of PIM-1 to primary amine groups, shows enhanced CO2 selectivity during mixed gas permeation studies with respect to single gas measurements for gas pairs involving CO2. This distinct and potentially useful behaviour was ascribed to the affinity of CO2 for the polymer amine groups. Here, we demonstrate that enhanced selectivity originates from both CO2 physisorption and chemisorption. A combination of 13C and 15N solid-state NMR spectroscopic analyses of a CO2-loaded amine-PIM-1 membrane allowed the identification and quantitative determination of both chemisorbed and physisorbed species and the characterization of polymer-CO2 interactions. Experiments with 13C isotopically enriched CO2 unequivocally demonstrated the conversion of 20% of the NH2 groups into carbamic acids at 298 K and a CO2 pressure of 1 bar. Chemisorption was supported by the strong heat of CO2 adsorption for amine-PIM-1 that was estimated as 50 kJ mol-1. Molecular dynamics simulations with models based on the experimentally determined polymer structure gave a detailed description of intra- and interchain hydrogen bond interactions in amine-PIM-1 after chemisorption, as well as of the effect of chemisorption on polymer porosity and physisorption.

In light of the importance of designing less energy-intensive and cleaner technologies for olefin purification, the current work aims to systematically enhance the separation of a challenging pair of olefin/paraffin gases, namely propene/propane. To achieve this goal, various blended membranes are fabricated by mixing cellulose acetate (CA), a carbohydrate-based biopolymer, with three different aprotic ionic liquids (ILs) including [BMIM]+[BF4]-, [BMIM]+[OTf]-, and [BMIM]+[Tf2N]-, which are used as additives, with a plasticizer effect, at concentrations in the range of 10-30%. Extensive physicochemical characterization of these membranes by DSC and TGA (thermal properties), Tensile tests (mechanical properties), X-ray diffraction and SEM (structural properties) show that ILs are well-dispersed within the polymeric matrix owing to the interactions between the ILs and CA functional groups. The incorporation of ILs leads to enhanced gas transport properties of the blended membranes compared to the neat one, generally improving their permeability. In particular, the blended membrane, incorporated with 30 % of [BMIM]+[Tf2N]-, increased the C3H6 permeability by 35 times and the C3H6/C3H8 selectivity by nearly two times compared to the neat CA membrane. These results suggest that ionic liquid-doped cellulose acetate membranes are potential candidates for efficiently separating the propene/propane gas pair.

Redox-switchable Polymers of Intrinsic Microporosity (PIMs) are a promising yet underexplored class of materials. Here, we introduce pi-extended dihydrophenazine-based PIMs for gas separation. The tert-butyl substituted Phen-PIM-1 stands out as a rare example of a redox-active switchable polymer with a high surface area (BET >600 m(2) g(-1)) and excellent balance of porosity, pore size, and gas selectivity. Phen-PIM-1 is soluble in N-methyl pyrrolidone (NMP), enabling membrane fabrication, while the methyl-substituted Phen-PIM-2 is insoluble, highlighting the role of bulky tert-butyl groups (tBu) in solubility and film formation. Gas separation studies, performed on powder (IAST), demonstrate outstanding performance, with CO2/N-2 selectivity up to 49. As a membrane material, Phen-PIM-1 shows competitive separation within the Robeson upper bound for several commercially important gas pairs, proving its potential for carbon capture and molecular sieving. Furthermore, these materials exhibit efficient and reversible redox switching upon chemical stimuli, leading to marked differences in properties and enhanced selectivity. This study establishes dihydrophenazine-based PIMs as a versatile platform for developing tunable, high-performance membranes for energy and environmental applications.

Heterogeneous catalysis is significantly enhanced by the use of highly porous polymers with specific functionalities, such as basic groups, which accelerate reaction rates. Polymers of intrinsic microporosity (PIMs) provide a unique platform for catalytic reactions owing to their high surface areas and customizable pore structures. We herein report a series of Troger's base polymers (TB-PIMs) with enhanced basicity, achieved through the incorporation of nitrogen-containing groups into their repeat units, such as triazine and triphenylamine. These polymers offer a perfect balance between the pore "swellability", which allows the use of substrates of various dimensions, and the basicity of their repeat units, which facilitates the use of reactants with diverse acidity. The catalytic activity is evaluated through the Knoevenagel condensation of benzaldehydes and various methylene species, conducted in the presence of ethanol as a green solvent and using a 1:1 ratio of the two reagents. The results highlight a significant improvement, with reactions reaching completion using just a 1% molar ratio of catalysts and achieving a 3-fold enhancement over previous results with 4-tert-butyl-benzaldehyde. Computational modeling confirms that the enhanced basicity of the repeat units is attributable to the polymer design. Additionally, preliminary studies are undertaken to assess the kinetics of the catalyzed condensation reaction.

This study shows the multistep synthesis of a series of Troger's base polymers of intrinsic microporosity (TB-PIMs) based on a hexaphenylbenzene (HPB) core, with a focus on evaluating their thermal stability, porosity, and CO2 capture performance. Both ladder and linear structures were prepared, designed to feature tunable nitrogen content and porosity. Our findings demonstrate that polymers with higher nitrogen content, such as tetra-TB-HPB, exhibit superior CO2 affinity and selectivity, attributed to enhanced interactions with CO2 and optimized micropore sizes. Linear TB-polymers 1 and 2 are also made for comparison and show competitive performance in carbon capture, suggesting that cost-effective, simpler-to-synthesize materials can achieve efficient gas separation. The study reveals that increased porosity significantly enhances CO2 capacity and selectivity, particularly in networked TB-HPB-PIMs with high surface areas and narrow micropores, achieving values up to 544 m2 g-1, CO2 uptake of 2.00 mmol g-1, and CO2/N2 selectivity of 45.6. The thermal properties of these materials, assessed via thermogravimetric analysis (TGA), show that TB-HPB-PIMs maintain robust thermal stability in nitrogen atmosphere, with tetra- and hexa-TB-HPBs leading the series. However, in oxidative environments, denser polymers such as TB-HPB and linear TB-polymer 1 demonstrate higher performance, likely due to restricted air diffusion. Overall, our findings highlight the critical need to balance porosity and thermal stability in TB-HPB-PIMs for applications in gas separation, carbon capture, and the potential for these polymers as flame retardant materials. Tetra-TB-HPB stands out as the most promising material for CO2 capture and thermal stability under inert conditions, while denser polymers like TB-HPB offer superior performance in oxidative environments.

Porphyrin-based porous materials are of growing interest as heterogeneous catalysts especially for reactions that are of importance to sustainability. Here we demonstrate that porous molecular crystals can be prepared by the simple co-crystallisation of tetraphenylporphyrin (TPP) with octa(2’,6’-di- iso -propylphenoxy)phthalocyanine or some of its metal complexes [(dipPhO) 8 PcM; M=H 2 , Al−OH, Ti=O, Mn−Cl, Fe−Cl, Co, Ni, Cu, Zn, Ga−Cl, Ag, In−Cl or Au−Cl]. This process is facilitated by the efficient formation of the supramolecular heterodimer between TPP and (dipPhO) 8 PcM, which is driven by the complementary shape and symmetry of the two macrocycles. The (dipPhO) 8 PcM component directs the crystal structure of the heterodimers to form Phthalocyanine Nanoporous Crystals (PNCs) of similar structure to those formed by (dipPhO) 8 PcM alone. The incorporation of TPP appears to partially stabilise the PNCs towards the removal of included solvent and for cocrystals containing (dipPhO) 8 PcCo stability can be enhanced further by the insitu addition of 4,4-bipyridyl to act as a “molecular wall tie”. These stabilised PNC/TPP cocrystals have a Brunauer–Emmett–Teller surface area ( SA BET ) of 454 m 2  g −1 and a micropore volume ( V mp ) of 0.22 mL g −1 . The reactivity of both macrocycles within the PNC/TPP co-crystals is demonstrated by insitu metal insertion.

Redox flow batteries (RFBs) based on aqueous organic electrolytes are a promising technology for safe and cost-effective large-scale electrical energy storage. Membrane separators are a key component in RFBs, allowing fast conduction of charge-carrier ions but minimizing the cross-over of redox-active species. Here, we report the molecular engineering of amidoxime-functionalized Polymers of Intrinsic Microporosity (AO-PIMs) by tuning their polymer chain topology and pore architecture to optimize membrane ion transport functions. AO-PIM membranes are integrated with three emerging aqueous organic flow battery chemistries, and the synergetic integration of ion-selective membranes with molecular engineered organic molecules in neutral-pH electrolytes leads to significantly enhanced cycling stability.

In this paper we tackle the challenge of gaining control of the photophysical properties of PAHs through a site-specific N-doping within the structural aromatic framework.

Redox flow batteries using aqueous organic-based electrolytes are promising candidates for developing cost-effective grid-scale energy storage devices. However, a significant drawback of these batteries is the cross-mixing of active species through the membrane, which causes battery performance degradation. To overcome this issue, here we report size-selective ion-exchange membranes prepared by sulfonation of a spirobifluorene-based microporous polymer and demonstrate their efficient ion sieving functions in flow batteries. The spirobifluorene unit allows control over the degree of sulfonation to optimize the transport of cations, whilst the microporous structure inhibits the crossover of organic molecules via molecular sieving. Furthermore, the enhanced membrane selectivity mitigates the crossover-induced capacity decay whilst maintaining good ionic conductivity for aqueous electrolyte solution at pH 9, where the redox-active organic molecules show long-term stability. We also prove the boosting effect of the membranes on the energy efficiency and peak power density of the aqueous redox flow battery, which shows stable operation for about 120 h (i.e., 2100 charge-discharge cycles at 100 mA cm −2 ) in a laboratory-scale cell.

The rapid advancement of membrane gas separation processes has spurred the development of new and more efficient membrane materials, including polymers of intrinsic microporosity. The full exploitation of such materials requires thorough understanding of their transport properties, which in turn necessitates the use of powerful and reliable characterization methods. Most methods focus on the permeability, diffusivity and solubility of single gases or only the permeability of mixed gases, while studies reporting the diffusion and solubility of gas mixtures are extremely rare. In this paper we report the use of a mass-spectrometric residual gas analyser to follow the transient phase of mixed gas transport through a benzotriptycene-based ultrapermeable polymer of intrinsic microporosity (PIM-DTFM-BTrip) and a polydimethylsiloxane (PDMS) membrane for comparison, via the continuous online analysis of the permeate. Computational analysis of the entire permeation curve allows the calculation of the mixed gas diffusion coefficients for all individual gases present in the mixture and the identification of non-Fickian diffusion or other anomalous behaviour. The mixed gas transport parameters were analysed by three different approaches (integral, differential and pulse signal), and compared with the results of the ‘classical’ time lag method for single gases. PDMS shows very similar results in all cases, while the transport in the PIM gives different results depending on the specific method and instrument used. This comparative study provides deep insight into the strengths and limitations of the different instruments and data elaboration methods to characterize the transport in rubbery and high free volume glassy membranes with fundamentally different properties and will be of help in the development of novel membrane materials.

Polymers of intrinsic microporosity (PIMs), such as the archetypal spirobisindane‐based PIM‐1, are among the most promising new materials for making gas separation membranes with high permeance for potential use in high‐throughput applications. Here it is shown that ultrapermeable PIMs can be prepared by fusing rigid and bulky triptycene (Trip) to the spirobisindane (SBI) unit. PIM‐SBI‐Trip and its copolymer with PIM‐1 (PIM‐1/SBI‐Trip) are both ultrapermeable after methanol treatment ( P CO2 > 20 000 Barrer). Old films, although less permeable, are more selective and therefore provide data that are close to the recently redefined Robeson upper bounds for the important CO 2 /CH 4 , CO 2 /N 2 , and O 2 /N 2 gas pairs. Temperature‐dependent permeation measurements and analysis of the entropic and energetic contributions of the gas transport parameters show that the enhanced performance of these polymers is governed by strong size‐sieving character, mainly due to the energetic term of the diffusivity, and related to their high rigidity. Both polymers show a relatively weak pressure‐dependence in mixed gas permeability experiments up to 6 bar, suggesting a potential use for CO 2 capture from flue gas or for the upgrading of biogas.

Building on the MOF approach to prepare porous materials, herein we report the engineering of porous BN-doped materials using tricarboxylic hexaarylborazine ligands, which are laterally decorated with functional groups at the full-carbon 'inner shell'. Whilst an open porous 3D entangled structure could be obtained from the double interpenetration of two identical metal frameworks derived from the methyl substituted borazine, the chlorine-functionalised linker undergoes formation of a porous layered 2D honeycomb structure, as shown by single-crystal X-ray diffraction analysis. In this architecture, the borazine cores are rotated by 60° in alternating layers, thus generating large rhombohedral channels running perpendicular to the planes of the networks. An analogous unsubstituted full-carbon metal framework was synthesised for comparison. The resulting MOF revealed a crystalline 3D entangled porous structure, composed by three mutually interpenetrating networks, hence denser than those obtained from the borazine linkers. Their microporosity and CO2 uptake were investigated, with the porous 3D BN-MOF entangled structure exhibiting a large apparent BET specific surface area (1091 m2  g-1 ) and significant CO2 reversible adsorption (3.31 mmol g-1 ) at 1 bar and 273 K.

A series of nine polymers of intrinsic microporosity (PIMs) derived from different bis-catechol monomers and 2,3,7,8-tetrafluoro-5,5′,10,10′-tetraoxidethianthrene (TOT) were synthesised and tested for their potential use as gas separation membranes.

Owing to their high surface area and superior adsorption properties, spirobifluorene polymers of intrinsic microporosity (PIMs), namely PIM-SBF-Me (methyl) and PIM-SBF-tBu ( tert -butyl), were used for the first time, to our knowledge, for the removal of methylene blue (MB) dye from wastewater. Spirobifluorene PIMs are known to have large surface area (can be up to 1100 m 2 g −1 ) and have been previously used mainly for gas storage applications. Dispersion of the polymers in aqueous solution was challenging owing to their extreme hydrophobic nature leading to poor adsorption efficiency of MB. For this reason, cationic (cetyl-pyridinium chloride), anionic (sodium dodecyl sulfate; SDS) and non-ionic (Brij-35) surfactants were used and tested with the aim of enhancing the dispersion of the hydrophobic polymers in water and hence improving the adsorption efficiencies of the polymers. The effect of surfactant type and concentration were investigated. All surfactants offered a homogeneous dispersion of the polymers in the aqueous dye solution; however, the highest adsorption efficiency was obtained using an anionic surfactant (SDS) and this seems owing to the predominance of electrostatic interaction between its molecules and the positively charges dye molecules. Furthermore, the effect of polymer dosage and initial dye concentration on MB adsorption were also considered. The kinetic data for both polymers were well described by a pseudo-second-order model, while the Langmuir model better simulated the adsorption process of MB dye on PIM-SBF-Me and the Freundlich model was more suitable for PIM-SBF-tBu. Moreover, the maximum adsorption capacities recorded were 84.0 and 101.0 mg g −1 for PIM-SBF-Me and PIM-SBF-tBu, respectively. Reusability of both polymers was tested by performing three adsorption cycles and the results substantiate that both polymers can be effectively re-used with insignificant loss of their adsorption efficiency (%AE). These preliminary results suggested that incorporation of a surfactant to enhance the dispersion of hydrophobic polymers and adsorption of organic contaminants from wastewater is a simple and cost-effective approach that can be adapted for many other environmental applications.