A stable polymeric chain configuration producing high performance PEBAX-1657 membranes for CO2 separation

Green synthesis of sulfonated cellulose/polyether block amide/polyethylene glycol diacrylate (SC/PEBAX/PEGDA) composite membrane by gamma radiation and sulfonation techniques for battery application

Sulfonated cellulose (SC) was successfully prepared through a two-step process of gamma radiation and subsequently sulfonation with potassium metabisulfite of microcrystalline cellulose extracted from sugarcane bagasse. The effect of gamma radiation dose on cellulose showed an increment of oxidation degree, which was evidenced by the intensity ratio of I1718 (carbonyl)/ I2892 (aliphatic) from FTIR analysis. The obtained SC was introduced into polyether block amide/polyethylene glycol diacrylate (PEBAX/PEGDA) polymer matrix as a reinforcement and hydrophilic filler for improving electrolyte affinity and thermal stability of its composite membrane. The increase of SC in PEBAX/PEGDA composite membranes resulted in enhancement of hydrophilicity, electrolyte uptake, and thermal stability compared to pristine composite membranes. However, the excess SC content in the composite membrane exhibited the low physical properties, caused by negligible dispersion on the surface membrane. With the optimum 2.0 wt% SC in PEBAX/PEGDA, the porosity, contact angle and electrolyte uptake capacity was found to be 64.0 %, 12.8° and 37.5 %, respectively. 2.0 wt% SC/PEBAX/PEGDA showed the outstanding thermal stability with negligible shrinkage <10 % at 150 °C whereas pristine PEBAX/PEGDA showed the shrinkage of 29 %. The obtained SC/PEBAX/PEGDA composite membrane is considered as a potential candidate to replace the commercial polyolefin-based separator in lithium-ion batteries.

A Review of the Recent Progress in the Development of Nanocomposites Based on Poly(ether-block-amide) Copolymers as Membranes for CO2 Separation

An inspiring challenge for membrane scientists is to exceed the current materials' performance while keeping the intrinsic processability of the polymers. Nanocomposites, as mixed-matrix membranes, represent a practicable response to this strongly felt need, since they combine the superior properties of inorganic fillers with the easy handling of the polymers. In the global strategy of containing the greenhouse effect by pursuing a model of sustainable growth, separations involving CO2 are some of the most pressing topics due to their implications in flue gas emission and natural gas upgrading. For this purpose, Pebax copolymers are being actively studied by virtue of a macromolecular structure that comprises specific groups that are capable of interacting with CO2, facilitating its transport with respect to other gas species. Interestingly, these copolymers show a high versatility in the incorporation of nanofillers, as proved by the large number of papers describing nanocomposite membranes based on Pebax for the separation of CO2. Since the field is advancing fast, this review will focus on the most recent progress (from the last 5 years), in order to provide the most up-to-date overview in this area. The most recent approaches for developing Pebax-based mixed-matrix membranes will be discussed, evidencing the most promising filler materials and analyzing the key-factors and the main aspects that are relevant in terms of achieving the best effectiveness of these multifaceted membranes for the development of innovative devices.

The assessment of honeycomb structure UiO-66 and amino functionalized UiO-66 metal-organic frameworks to modify the morphology and performance of Pebax®1657-based gas separation membranes for CO2 capture applications

A new type of honeycomb structured UiO-66 metal-organic frameworks (MOF) was synthesized and amino functionalized followed by employing them to prepare mixed matrix membranes (MMM). The influences of dimethylformamide (DMF) and H₂O/ethanol (70/30 wt.%) blend were firstly investigated on morphology, structure, and CO₂/CH₄ separation efficiency of Pebax®1657 membranes. Based on the transmission electron microscopy (TEM) analysis, the synthesized MOF has 15 nm in diameter. DMF led to the formation of a more crystalline (based on X-ray diffraction (XRD) analysis) and more porous structure. Higher CO₂ permeability and CO₂/CH₄ selectivity were observed as DMF was employed to fabricate neat membranes. Scanning electron microscopy (SEM) exhibited MOF agglomeration as the UiO-66 was used while the nanoparticle dispersion was enhanced when UiO-66-NH₂ was exploited. Fourier transform infrared spectroscopy (FTIR) confirmed the successful MOF incorporation into the MMMs. Ultimately, the gas separation experiments showed that CO₂ permeability was enhanced compared to the neat membrane by 44.7% and 49.4% as 10 wt.% UiO-66 and UiO-66-NH₂ were used, respectively. Moreover, the Pebax®1657-UiO-66-NH₂ MMMs exhibited 71.7% and 34.5% improvement in selectivity of CO₂/N₂ and CO₂/CH₄, respectively, owing to enhancing CO₂-OH interactions while the CO₂/O₂ was declined by 8.8%.

Enhancing Gas Permeation Properties of Pebax® 1657 Membranes via Polysorbate Nonionic Surfactants Doping

Composite membranes were prepared by co-casting, incorporating two nonionic surfactants in a poly(ether-block-amide), Pebax® 1657 up to 50 wt %. These polysorbate nonionic surfactants contain many ethylene oxide units and are very CO2-philic agents; thereby, they can be exploited as membrane additives for gas separation involving carbon oxide. Dynamic light scattering analysis proved a higher stability of additionated Pebax® 1657 solutions with respect to those containing only the copolymer. Scanning electron microscopy showed a regular membrane morphology without pores or defects for all investigated samples. If on the one hand the addition of the additive has depressed the mechanical properties, on the other, it has positively influenced the gas transport properties of Pebax® 1657 films. CO2 permeability increased up to two or three times after the incorporation of 50 wt % additive in copolymer matrix, while the selectivity was not significantly affected. The effect of temperature on permanent gas transport properties was studied in the range of 15-55 °C.