Global water scarcity is a threat that can be alleviated through membrane filtration technologies. However, the widespread adoption of membranes faces significant challenges, primarily due to membrane biofouling. This is the reason why membrane modifications have been under increasing investigation to address the fouling issues. Antibacterial membranes, designed to combat biofouling by eliminating microorganisms, offer a promising solution. Within this study, flat sheet ultrafiltration (UF) membranes with integrated photocatalytic zinc oxide (ZnO) nanoparticles were developed, characterized, and assessed through filtration and fouling tests. The antibacterial properties of the membranes were conducted in static tests using Gram-negative bacteria—Escherichia coli—and natural tap water biofilm. The results demonstrated a notable enhancement in membrane surface wettability and fouling resistance. Furthermore, the incorporation of ZnO resulted in substantial photocatalytic antibacterial activity, inactivating over 99.9% of cultivable E. coli. The antibacterial activity persisted even in the absence of light. At the same time, the persistence of natural tap water organisms in biofilms of modified membranes necessitates further in-depth research on complex biofilm interactions with such membranes.

Tailored binder polymers enable high current densities for anion-exchange water electrolysis (AEMWE) for green hydrogen production without the necessity of noble metal catalysts.

State-of-the-art Li batteries suffer from serious safety hazards caused by the reactivity of lithium and the flammable nature of liquid electrolytes. This work develops highly efficient solid-state electrolytes consisting of imidazolium-containing polyionic liquids (PILs) and lithium bis(trifluoromethane sulfonyl)imide (LiTFSI). By employing PIL/LiTFSI electrolyte membranes blended with poly(propylene carbonate) (PPC), we addressed the problem of combining ionic conductivity and mechanical properties in one material. It was found that PPC acts as a mechanically reinforcing component that does not reduce but even enhances the ionic conductivity. While pure PILs are liquids, the tricomponent PPC/PIL/LiTFSI blends are rubber-like materials with a Young’s modulus in the range of 100 MPa. The high mechanical strength of the material enables fabrication of mechanically robust free-standing membranes. The tricomponent PPC/PIL/LiTFSI membranes have an ionic conductivity of 10−6 S·cm−1 at room temperature, exhibiting conductivity that is two orders of magnitude greater than bicomponent PPC/LiTFSI membranes. At 60 °C, the conductivity of PPC/PIL/LiTFSI membranes increases to 10−5 S·cm−1 and further increases to 10−3 S·cm−1 in the presence of plasticizers. Cyclic voltammetry measurements reveal good electrochemical stability of the tricomponent PIL/PPC/LiTFSI membrane that potentially ranges from 0 to 4.5 V vs. Li/Li+. The mechanically reinforced membranes developed in this work are promising electrolytes for potential applications in solid-state batteries.

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A tetra-ester (TE) functionalized organic compound was synthesized for the restoration the mechanical properties of the PVC/Mg(OH)2 nanocomposites. The organically modified Mg(OH)2 nanoparticles (OMN) were prepared by surface modification of Mg(OH)2 nanoparticles (MDH) using a methylated tetra-phenol (TP) organic compound to achieve the homogeneous MDH distribution in the nanocomposite matrix. The results of FT-IR, XRD, and FE-SEM revealed the successful surface treating of MDH. The PVC nanocomposites were prepared by solvent blending and casting method. From the TGA analyses, the 10% mass loss temperature and the char yield of PVC containing 3% by mass of OMN and 3% by mass of TE, in N2 atmosphere, increased by 13 °C and 7%, respectively, compared to unfilled PVC. From the microscale combustion calorimeter, a decreasing heat release rate from 125.2 to 92.8 W g–1 was observed for PVC film filled with 6% by mass of each additive, compared to unfilled PVC. The tensile test results revealed that TE and OMN have been effective for the improvement of the PVC tensile strength. For example, incorporating only 6% by mass of each filler led to an improvement in tensile strength from 58.99 to 80.58 MPa, compared to unfilled PVC.

Hydrazide-hydrazone based polyamide (HHPA) was synthesized from an aromatic diamine containing hydrazide-hydrazone group and dodecanedioic acid via direct polycondensation. The surface modified hydroxyapatite (SMHA) was prepared using a modification process of hydroxyapatite nanoparticles (HAN) with imine functionalized polyethyleneimine (FPEI). The new pol(ylactic acid) (PLA)/HAN/HHPA nanocomposites with increased heat and combustion resistance, and improved mechanical and gas barrier properties were fabricated using solution casting method. The structure and morphology of the prepared PLA nanocomposites were evaluated using FTIR, FE-SEM, and XRD techniques. The synergistic effect of SMHA and HHPA was studied on the heat and combustion resistance, gas barrier properties, and mechanical strength of PLA. The findings exhibited that HAN was homogeneously dispersed in the PLA polymeric network, due to the excellent interfacial interactions. The TGA results of nanocomposites revealed that PLA containing 3 mass% of each SMHA and HHPA additives, named PHP6, offers more heat resistance, in both N2 and air environment, compared to the neat PLA. According to the MCC results, the heat release rate peaks reduced from 555 W/g to 357 W/g for PLA containing 6 mass% of each SMHA and HHPA additives, named PHP12. From mechanical test, the tensile strength of PHP6 was obtained 88.27 MPa, which was 48 MPa higher than the neat PLA. Furthermore, the gas barrier studies for CO2 and N2 indicated that the incorporation of both HHPA and SMHA results in reduced permeability and solubility coefficients compared to the neat PLA, where PHP2 and PHP6 samples outperform other samples.

Rapid population growth and the associated rise in industrialization and food production have resulted in a tremendously increased demand for clean water.

Flexible antibacterial materials have gained utmost importance in protection from the distribution of bacteria and viruses due to the exceptional variety of applications. Herein, we demonstrate a readily scalable and rapid single-step approach for producing durable ZnO nanoparticle antibacterial coating on flexible polymer substrates at room temperature. Substrates used are polystyrene, poly(ethylene-co-vinyl acetate) copolymer, poly(methyl methacrylate), polypropylene, high density polyethylene and a commercial acrylate type adhesive tape. The deposition was achieved by a spin-coating process using a slurry of ZnO nanoparticles in toluene. A stable modification layer was obtained when toluene was a solvent for the polymer substrates, namely polystyrene and poly(ethylene-co-vinyl acetate). These coatings show high antibacterial efficiency causing >5 log decrease in the viable counts of Gram-negative bacteria Escherichia. coli and Gram-positive bacteria Staphylococcus aureus in 120 min. Even after tapping these coated surfaces 500 times, the antibacterial properties remained unchanged, showing that the coating obtained by the presented method is very robust. In contrast to the above findings, the coatings are unstable when toluene is not a solvent for the substrate.

The preparation of hybrid proton conductive membranes that comprise of covalently linked interpenetrating polymer and inorganic networks is reported. The hybrid membranes are synthesized via simultaneous photo-initiated polymerization and sol-gel processing. The simultaneous processing permeates fabrication of the membranes that comprises covalently cross-linked polymeric and inorganic networks. The membranes are characterized by attenuated total reflectance-Fourier transform infrared spectroscopy, scaning electron microsopy, thermogravimetric analysis, differential scanning calorimetry, in order to confirm their chemical composition, structure, and morphology. An addition of 3-methacryloxypropyl trimethoxysilane into the sol-gel composition allows the formation of covalent linkages between polymeric and inorganic networks, which facilitates a uniform distribution of the molecular components across the fabricated membranes. The incorporation of the silica network leads to an increase in water retention and proton conductivity of hybrid membranes as compared to their purely polymeric analogues.

Membrane technology provides a reliable and powerful solution to combat the global water crisis by producing fresh water through sustainable desalination. However, the decline in system performance due to membrane biofouling is a limitation and significant efforts have been made to explore fouling control mechanisms and develop simple methods to inhibit or eliminate membrane fouling. Nanotechnology has increased the number of options for the development of antibiofouling membranes by incorporating nanoparticles within the polyamide layer to produce a thin‐film nanocomposite (TFN) structure. This review presents recent advances in the preparation of antifouling TFN membranes and incorporation of different nanoparticles into the design. The review also discusses the strategies and mechanisms for reducing membrane fouling and proposes a future outlook for the field.

Hydrogen production using water electrolysers equipped with an anion exchange membrane (AEM), a pure water feed and cheap components such as platinum group metal-free catalysts and stainless steel bipolar plates (BPP) can challenge proton exchange membrane (PEM) electrolysis systems as the state of the art. For this to happen the performance of the AEM electrolyzer must match the compact design, stability, H-2 purity and high current densities of PEM systems. Current research aims at bringing AEM water electrolysis technology to an advanced level in terms of electrolysis cell performance. Such technological advances must be accompanied by demonstration of the cost advantages of AEM systems. The current state of the art in AEM water electrolysis is defined by sporadic reports in the academic literature mostly dealing with catalyst or membrane development. The development of this technology requires a future roadmap for systematic development and commercialization of AEM systems and components. This will include basic and applied research, technology development & integration, and testing at a laboratory scale of small demonstration units (AEM electrolyzer shortstacks) that can be used to validate the technology (from TRL 2-3 currently to TRL 4-5). This review paper gathers together recent important research in critical materials development (catalysts, membranes and MEAs) and operating conditions (electrolyte composition, cell temperature, performance achievements). The aim of this review is to identify the current level of materials development and where improvements are required in order to demonstrate the feasibility of the technology. Once the challenges of materials development are overcome, AEM water electrolysis can drive the future use of hydrogen as an energy storage vector on a large scale (GW) especially in developing countries.

This report presents a study about the morphology of a cross-linked aromatic polyamide (PA) film in its dry and wet state using small-angle neutron scattering (SANS), positron annihilation lifetime spectroscopy (PALS), and scanning electron microscopy (SEM). PA is used as active skin layer for reverse osmosis membranes and determines the selectivity of the membrane with respect to water and salt molecules. This selectivity of PA is largely determined from its morphology. The PA film scatters the neutrons much stronger and shows a different profile as expected from randomly distributed nanoscopic large pores. SANS contrast variation, using super-critical CO2 as contrast medium, confirms that pores are the only scattering centers. The analysis shows that interconnected pores of an average radius of about 16 angstrom determine the scattering. The pores are formed as a network of channels showing a fractal structure. PALS determines pores of similar to 6 angstrom diameter representing the diameter of such channels. The volume fraction of the pores is estimated as - 10% which after water up-take increases by similar to 30% due to slightly swelling of the pores.

Free-standing polyelectrolyte multilayer membranes have been formed by the layer-by-layer technique using a dip-coating apparatus. The polymer-chain mobility has been studied by 1 H relaxation in the rotating frame T 1rho NMR with 13 C chemical shift resolution. For each of the individual polymers a single relaxation component has been observed for all resolved signals. In the multilayer a significantly different relaxation time T 1rho has been observed with a minor second component. The interaction between the oppositely charged polyelectrolytes influences the molecular mobility.

The preparation of quaternary ammonium salts containing allyl and methallyl groups from dimethylamine and pyrrolidine, and the free-radical initiated cyclopolymerization of these salts is described. It is shown by NMR analysis that poly(ammonium salts) are formed consisting of pyrrolidinium and azoniaspiro[4.4]nonane containing repeating units respectively with one or even two adjacent quaternary carbon centers along the chain. The ability to polymerize decreased from diallyl over allylmethallyl to dimethallyl monomers. Already polymers from diallylammonium salts showed sufficient stability in alkaline medium at 80°C over a period of 168h and for additional 18h at 120°C.

Despite great effort that has been made to reduce and understand fouling, this phenomenon is still a major problem in membrane applications. Numerous methods, both from a chemical and engineering point of view, have been introduced to overcome this problem. In this contribution, we report on the modification of membranes with polyelectrolytes and polyelectrolyte multilayers utilizing two of the mentioned strategies. The effect of surface modification on the fouling behavior as well as on the critical flux will be discussed on two examples, microfiltration membranes and RO membranes.

Activated carbon electrodes for capacitive deionization (CDI) have been prepared using poly(arylene ether sulfone) random copolymers as binders. Due to the reduced mechanical strength and enhanced swelling of the polymers compared with PVDF binder, a 15 wt.% composition was found to be required to adequately bind the carbon particles. The hydrophilic nature of the polymers increased the wettability of the electrodes, however CV and EIS testing revealed a loss in capacitance compared with electrodes prepared with PVDF. This is thought to have been a result of polymer swelling, which reduced particle contact and hence charge transfer pathways within the carbon electrodes. As a result, poor micropore double layer formation was observed. Promisingly, EIS testing showed low charging resistance compared with electrodes prepared with PVDF, indicating the potential for hydrophilic polymers to be used as binders in CDI electrodes if charge transfer pathways between carbon particles can be maintained.

This chapter reviews the current state of the art in membranes for direct methanol fuel cells (DMFCs), with a particular focus on research developments. The focus is exclusively on membranes; however, given the tight integration that is necessary between membranes and the adjacent fuel/oxidant distribution layers, catalysts, and support materials, there is some mention of these materials as they must necessarily be compatible with the selected membrane. To illustrate the basic principles of DMFC operations, the chapter presents a typical, liquid-feed cell with a cation exchange membrane. The most well-known and well-studied membrane materials for DMFCs are perfluorosulfonic acid membranes, such as Nafion. These macromolecules combine two different functionalities in a single macromolecule: first, the hydrophobic nature, which impacts the high chemical and thermal stability, and second, the hydrophilic sulfonic acid regions, which are responsible for the water update and ion exchange capability.