A detailed analysis of the basic transport parameters of two triptycene-based polymers of intrinsic microporosity (PIMs), the ultrapermeable PIM-TMN-Trip and the more selective PIM-BTrip, as a function of temperature from 25°C to 55°C, is reported. For both PIMs, high permeability is based on very high diffusion and solubility coefficients. The contribution of these two factors on the overall permeability is affected by the temperature and depends on the pene-trant dimensions. Energetic parameters of permeability, diffusivity and solubility are calculated using Arrhenius-van’t Hoff equations and compared with those of the archetypal PIM-1 and the ultrapermeable but poorly selective poly(trimethylsilylpropyne) (PTMSP). This considers, for the first time, the role of entropic and energetic selectivities in the diffusion process through highly rigid PIMs. This analysis demonstrates how energetic selectivity dominates the gas transport properties of the highly rigid triptycene PIMs and enhances the strong size-sieving character of these ultrapermeable polymers.

An increasing number of high-performing gas separation membranes is reported almost on a daily basis, yet only a few of them have reached commercialisation while the rest are still considered pure research outcomes. This is often attributable to a rapid change in the performance of these separation systems over a relatively short time. A common approach to address this issue is the development of mixed matrix membranes (MMMs). These hybrid systems typically utilise either crystalline or amorphous additives, so-called fillers, which are incorporated into polymeric membranes at different loadings, with the aim to improve and stabilise the final gas separation performance. After a general introduction to the most relevant models to describe the transport properties in MMMs, this review intends to investigate and discuss the main advantages and disadvantages derived from the inclusion of fillers of different morphologies. Particular emphasis will be given to the study of the compatibility at the interface between the filler and the matrix created by the two different classes of additives, the inorganic and crystalline fillers vs. their organic and amorphous counterparts. It will conclude with a brief summary of the main findings.

Low-temperature electrolysis by using polymer electrolyte membranes (PEM) can play an important role in hydrogen energy transition. This work presents a study on the performance of a proton exchange membrane in the water electrolysis process at room temperature and atmospheric pressure. In the perspective of applications that need a device with small volume and low weight, a miniaturized electrolysis cell with a 36 cm² active area of PEM over a total surface area of 76 cm² of the device was used. H₂ and O₂ production rates, electrical power, energy efficiency, Faradaic efficiency and polarization curves were determined for all experiments. The effects of different parameters such as clamping pressure and materials of the electrodes on polarization phenomena were studied. The PEM used was a catalyst-coated membrane (Ir-Pt-Nafion™ 117 CCM). The maximum H₂ production was about 0.02 g min⁻¹ with a current density of 1.1 A cm⁻² and a current power about 280 W. Clamping pressure and the type of electrode materials strongly influence the activation and ohmic polarization phenomena. High clamping pressure and electrodes in titanium compared to carbon electrodes improve the cell performance, and this results in lower ohmic and activation resistances.

In this work, thin film composite (TFC) membranes were fabricated with the selective layer based on a blend of polyimide Matrimid^®5218 and polymer of intrinsic microporosity (PIM) composed of Tröger’s base, TB, and dimethylethanoanthracene units, PIM-EA(Me₂)-TB. The TFCs were prepared with different ratios of the two polymers and the effect of the PIM content in the blend of the gas transport properties was studied for pure He, H₂, O₂, N₂, CH₄, and CO₂ using the well-known time lag method. The prepared TFC membranes were further characterized by IR spectroscopy and scanning electron microscopy (SEM). The role of the support properties for the TFC membrane preparation was analysed for four different commercial porous supports (Nanostone Water PV 350, Vladipor Fluoroplast 50, Synder PAN 30 kDa, and Sulzer PAN UF). The Sulzer PAN UF support with a relatively small pore size favoured the formation of a defect-free dense layer. All the TFC membranes supported on Sulzer PAN UF presented a synergistic enhancement in CO₂ permeance, and CO₂/CH₄ and CO₂/N₂ ideal selectivity. The permeance increased about two orders of magnitude with respect to neat Matrimid, up to ca. 100 GPU, the ideal CO₂/CH₄ selectivity increased from approximately 10 to 14, and the CO₂/N₂ selectivity from approximately 20 to 26 compared to the thick dense reference membrane of PIM-EA(Me₂)-TB. The TFC membranes exhibited lower CO₂ permeances than expected on the basis of their thickness—most likely due to enhanced aging of thin films and to the low surface porosity of the support membrane, but a higher selectivity for the gas pairs CO₂/N₂, CO₂/CH₄, O₂/N₂, and H₂/N₂.