The role of halogens in polychlorotrifluoroethylene (PCTFE) in membrane gas separations

Tunable Gas Permeation Behavior through Robust, Freestanding Self-Assembled Metal Nanoparticle Membranes

Membrane-based gas separation offers a promising alternative route to energy-intensive industrial gas separation processes. Conventional microporous membranes often exhibit low gas selectivities for gases with similar kinetic diameters, primarily due to large pore sizes and reliance on Knudsen selectivity. In this study, we present self-assembled gold nanoparticle (Au NP) membranes that enable molecular gas separation within the kinetic diameter range of small gases such as H2, CO2, and O2. By grafting silane molecules of varying sizes onto NP ligands, the gas selectivity of these membranes becomes tunable. This strategy achieves remarkably high gas selectivities of 192 and 35 for H2/CO2 and CO2/O2 gas pairs. Moreover, the Au NP membrane demonstrates a mixed gas selectivity of up to 30 for H2/CO2 even at room temperature, establishing its potential as a novel class of gas separation membranes with high and tunable selectivity.

Extending The Calendar Life of Fiber Lithium-Ion Batteries to 200 Days with Ultra-High Barrier Polymer Tubes

Scalable fiber lithium-ion batteries (FLIBs) have garnered significant attention due to huge potential applications in wearable technology. However, their widespread applications have been limited by inadequate cycle and calendar life, primarily due to the high permeability of the encapsulation layer to water vapor in ambient air. To address this challenge, an ultra-high barrier composite tube is developed by blending polytrifluorochloroethylene (PCTFE) with organically modified montmorillonite (OMMT) for the continuous packaging of FLIBs. Due to the high crystallinity (≈40.21%) and small free volume (103.443 Å3), the PCTFE tube exhibited a low water vapor transmission rate (WVTR) of 0.123 mg day-1 pkg-1. Furthermore, through the melt extrusion, OMMT with its plate-like morphology are fully exfoliated and dispersed within the PCTFE matrix. This created more complex pathways for water, increasing the diffusion path length and thereby reducing WVTR to 0.006 mg day-1 pkg-1. This innovation enabled an ultra-long calendar life of 200 days and cycle life of 870 cycles for FLIBs, with over 80% capacity retention in ambient air. Additionally, 2%OMMT-PCTFE-FLIBs exhibited excellent flexibility, retaining an impressive 85.31% capacity after 10 000 bending cycles. This research presents a simple yet effective approach to enhance the lifetime and practicality of FLIBs through building a high-performance polymer-based encapsulation layer.

Antibacterial Properties of Plasma-Activated Perfluorinated Substrates with Silver Nanoclusters Deposition

This article is focused on the evaluation of surface properties of polytetrafluoroethylene (PTFE) nanotextile and a tetrafluoroethylene-perfluoro(alkoxy vinyl ether) (PFA) film and their surface activation with argon plasma treatment followed with silver nanoclusters deposition. Samples were subjected to plasma modification for a different time exposure, silver deposition for different time periods, or their combination. As an alternative approach, the foils were coated with poly-L-lactic acid (PLLA) and silver. The following methods were used to study the surface properties of the polymers: goniometry, atomic force microscopy, and X-ray photoelectron microscopy. By combining the aforementioned methods for material surface modification, substrates with antibacterial properties eliminating the growth of Gram-positive and Gram-negative bacteria were prepared. Studies of antimicrobial activity showed that PTFE plasma-modified samples coated with PLLA and deposited with a thin layer of Ag had a strong antimicrobial effect, which was also observed for the PFA material against the bacterial strain of S. aureus. Significant antibacterial effect against S. aureus, Proteus sp. and E. coli has been demonstrated on PTFE nanotextile plasma-treated for 240 s, coated with PLLA, and subsequently sputtered with thin Ag layer.

Functionalized KIT-6/Polysulfone Mixed Matrix Membranes for Enhanced CO2/CH4 Gas Separation

The development of mixed matrix membranes (MMMs) for effective gas separation has been gaining popularity in recent years. The current study aimed at the fabrication of MMMs incorporated with various loadings (0–4 wt%) of functionalized KIT-6 (NH₂KIT-6) [KIT: Korea Advanced Institute of Science and Technology] for enhanced gas permeation and separation performance. NH₂KIT-6 was characterized by field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), and N₂ adsorption–desorption analysis. The fabricated membranes were subjected to FESEM and FTIR analyses. The effect of NH₂KIT-6 loading on the CO₂ permeability and ideal CO₂/CH₄ selectivity of the fabricated membranes were investigated in gas permeation and separation studies. The successfulness of (3-Aminopropyl) triethoxysilane (APTES) functionalization on KIT-6 was confirmed by FTIR analysis. As observed from FESEM images, MMMs with no voids in the matrix were successfully fabricated at a low NH₂KIT-6 loading of 0 to 2 wt%. The CO₂ permeability and ideal CO₂/CH₄ selectivity increased when NH₂KIT-6 loading was increased from 0 to 2 wt%. However, a further increase in NH₂KIT-6 loading beyond 2 wt% led to a drop in ideal CO₂/CH₄ selectivity. In the current study, a significant increase of about 47% in ideal CO₂/CH₄ selectivity was achieved by incorporating optimum 2 wt% NH₂KIT-6 into the MMMs.

Evaluation of the Properties, Gas Permeability, and Selectivity of Mixed Matrix Membrane Based on Polysulfone Polymer Matrix Incorporated with KIT-6 Silica

Mixed matrix membranes (MMMs) separation is a promising technology for gas permeation and separation involving carbon dioxide (CO₂). However, finding a suitable type of filler for the formation of defect-free MMMs with enhancement in gas permeability remains a challenge. Current study focuses on synthesis of KIT-6 silica and followed by the incorporation of KIT-6 silica as filler into polysulfone (PSF) polymer matrix to fabricate MMMs, with filler loadings of 0–8 wt %. The effect of KIT-6 incorporation on the properties of the fabricated MMMs was evaluated via different characterization techniques. The MMMs were investigated for gas permeability and selectivity with pressure difference of 5 bar at 25 °C. KIT-6 with typical rock-like morphology was synthesized. Incorporation of 2 wt % of KIT-6 into PSF matrix produced MMMs with no void. When KIT-6 loadings in the MMMs were increased from 0 to 2 wt %, the CO₂ permeability increased by ~48%, whereas the ideal CO₂/CH₄ selectivity remained almost constant. However, when the KIT-6 loading in PSF polymer matrix was more than 2 wt %, the formation of voids in the MMMs increased the CO₂ permeability but sacrificed the ideal CO₂/CH₄ selectivity. In current study, KIT-6 was found to be potential filler for PSF matrix under controlled KIT-6 loading for gas permeation.

Fluorine in the structure of polymers: influence on the gas separation properties

Results of studies on the separation of gases and vapours using fluorine-containing polymers are integrated and analyzed. Methods for the synthesis of these polymers are considered, including direct gas-phase fluorination, plasma polymerization of fluorine-containing precursors and modification of organic polymers, as well as diverse syntheses of monomers containing C−F and C−CF3 bonds and their subsequent polymerization. Structure – property relationships for these polymers are elucidated and their actual and potential applications as membrane materials are discussed.

The bibliography includes 165 references.