Basic Alkylamine Functionalized PAF-1 Hybrid Membrane with High Compatibility for Superior CO2 Separation from Flue Gas

Functionalized porous aromatic frameworks (PAFs) are excellent candidate materials for hybrid membrane fabrication. However, tailoring PAFs for membrane CO₂ separation with desirable performance is still a challenge. Here, facile fabrication of functional hybrid alkylamine-modified PAF-1 containing membranes with high compatibility for efficient CO₂/N₂ separation is reported. The methylamino groups are installed on PAF-1 resulting in PAF-1-CH₂NH₂ that has a high surface area of over 1400 m² g^–1 and unique CO₂ adsorption with CO₂/N₂ thermodynamic selectivity of over 1000. Amidation reaction is developed for PAF-1-CH₂NH₂ cross linking with cPIM-1 (carboxylic polymer of intrinsic microporosity), giving a homogenous compatible membrane of PAF-1-CH₂NH₂—cPIM-1 with outstanding CO₂ permeability (≈10790 Barrer) and high CO₂/N₂ permselectivity (≈43). This membrane outperforms the counterparts derived from parent PAF-1 and phenylamine PAF-1 and possesses superior performance to other relevant membranes for CO₂/N₂ separation. Such a membrane can selectively and stably separate CO₂ from N₂ in a simulated flue gas mixture, demonstrating its huge potential in carbon capture.     

Investigation of the Reaction Kinetics of Poly(butylene terephthalate) and Epoxide Chain Extender

Polyesters, such as poly (butylene terephthalate) (PBT), owe a rather low melt strength, which is considered as not beneficial for foaming. To overcome this issue, a typical attempt is the incorporation of chemical modifications—so-called chain extenders (CE)—in the reactive extrusion process. In this study, the reaction kinetic variables are investigated depending on the material and process parameters. For this purpose, different series of experiments are performed with varying PBT with different molecular weights and the commonly used CE, Joncryl ADR4468, on a micro compounder. The screw force is recorded and analyzed using an Avrami and an Arrhenius plot. First, the amount of CE is systematically varied. To study the course of the reaction in more detail, the reaction is stopped in a series of measurements (10, 30, 60, and 90 s after complete filling). Gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FT-IR), and Raman spectra are recorded. In the second series, the effect of processing temperatures between 250 and 270 °C is investigated, and finally, in the third series, the average molecular weight of PBT is varied. It could be shown that the activation energy seems to be dependent on the initial molecular weight; lower molecular weights result in lower activation energy.