Effect of nano-silica on gas permeation properties of polyether-based polyurethane membrane in the presence of esterified canola oil diol as a nucleation agent for hard segments

Recent advancements in polyurethane-based membranes for gas separation

Gas separation membranes are critical in a variety of environmental research and industrial applications. These membranes are designed to selectively allow some gases to flow while blocking others, allowing for the separation and purification of gases for a variety of applications. Therefore, the demand for fast and energy-efficient gas separation techniques is of central interest for many chemical and energy production diligences due to the intensified levels of greenhouse and industrial gases. This encourages the researchers to innovate techniques for capturing and separating these gases, including membrane separation techniques. Polymeric membranes play a significant role in gas separations by capturing gases from the fuel combustion process, purifying chemical raw material used for plastic production, and isolating pure and noncombustible gases. Polyurethane-based membrane technology offers an excellent knack for gas separation applications and has also been considered more energy-efficient than conventional phase change separation methodologies. This review article reveals a thorough delineation of the current developments and efforts made for PU membranes. It further explains its uses for the separation of valuable gases such as carbon dioxide (CO2), hydrogen (H2), nitrogen (N2), methane (CH4), or a mixture of gases from a variety of gas spillages. Polyurethane (PU) is an excellent choice of material and a leading candidate for producing gas-separating membranes because of its outstanding chemical chemistry, good mechanical abilities, higher permeability, and variable microstructure. The presence of PU improves several characteristics of gas-separating membranes. Selectivity and separation efficiency of PU-centered membranes are enhanced through modifications such as blending with other polymers, use of nanoparticles (silica, metal oxides, alumina, zeolite), and interpenetrating polymer networks (IPNs) formation. This manuscript critically analyzes the various gas transport methods and selection criteria for the fabrication of PU membranes. It also covers the challenges facing the development of PU-membrane-based separation procedures.

Effect of organic/inorganic nanoparticles on performance of polyurethane nanocomposites for potential wound dressing applications

This study focuses on the evaluation and modification of polyurethane (PU) membranes containing organic and inorganic nanoparticles for potential use as a wound dressing. For the purpose of PU nanocomposite preparation, chitosan (CS) was converted into nanoparticles by the ionic-gelation method to improve its blending capability with the PU matrix. These CS nanoparticles (nano-CS) were obtained as a hydrophilic organic filler with different contents and were utilized along with inorganic titanium dioxide (TiO₂) nanoparticles in the nanocomposite membrane preparation. The membranes were prepared using phase inversion technique and their microstructure was controlled by manipulating the solvent non-solvent exchange rate. Obtained results demonstrate that addition of polymer solvent to nonsolvent induced a microstructure alteration from finger-like to sponge-like, which is more suitable for fluid uptake and consequently more useful for wound dressing applications. Similar results were obtained by introduction of nanoparticles to membranes. Due to the polar nature of nanoparticles and their effects on PU structure, prepared membranes showed 71.5% improve in swelling when compared to neat PU. Moreover, the reinforcement effect of nanoparticles caused an 18.94% increase in ultimate tensile strength in comparison with bare PU film, while elongation at break was not affected considerably. In addition, prepared PU nanocomposite films showed suitable antibacterial activity of 69% against Staphylococcus aureus and did not show any toxicity to human fibroblast cells. Based on these results, simultaneous use of TiO₂ and chitosan nanoparticles can improve both physical and antibacterial properties of PU as an ideal wound dressing.