فصلنامه مواد پیشرفته و پوشش های نوین
پیاپی 43 (تابستان 1402)

Since the discovery of Ti3C2 MXene in 2011, continuous research has been carried out in the development of new MAX phases and the extraction of MXene from them. MXene has a series of exceptional properties due to its unique structure, excellent hydrophilicity, and conductivity of adjustable surface chemical functional groups. In this paper, a comprehensive review of the etchants widely used for the etching of A element from MAX phases leading to the formation of Maxene is also discussed. Similar to other 2D materials, due to strong van der Waals forces, MXene layers inevitably undergo stacking, leading to a severe loss of electrochemically active sites. If the accumulation of MXene layers can be prevented effectively, their electrochemical performance will increase. Therefore, in the next part of the article, the compounds that lead to an increase in the distance between the MXene layers are introduced, and finally the surface terminals such as -O, -OH, -F groups in MXene, which significantly affect their properties, are presented.

In this work, three novel 1,4-butane sultone-based Brønsted acidic ionic liquids with hydrogen sulfate conter-anion are prepared. These newly introduced ionic liquids were synthesized from a two-steps reaction. The reaction includes ring opening of 1,4-butane sultone using 1,4-disubstituted 1,2,3-triazole as nitrogen nucleophile sources to obtain zwitterions and then follow by acidification treatment with sulfuric acid to obtain novel Brønsted acidic ionic liquid. The prepared task specific ionic liquids and their stable intermediates were characterized by FT-IR, 1HNMR and 13C-NMR analysis techniques. Their catalytic efficiency was checked for the preparation of symmetric 3,3′-diaryloxindoles compounds. It was found that the introduced acidic ionic liquids are completely green, environmental benign, task specific and have high catalytic stability. These novel acidic ionic liquids are simply separable by extraction from organic phase by solving in water up to eight consecutive runs and give the target products in short reaction times at high yields. This catalyst could be considered as great alternative for old previously reported catalysts.

Recently, plasmonic nanoparticles with unique optical properties have been used in nanomedicine ranging from optical biosensing to bioimaging to drug delivery. Meanwhile, gold nanoparticles with very small and uniform size are desirable for these applications due to their low toxicity. In this project, reduction of gold by sodium borohydride (NaBH4) led to preparation of metal nanoparticles anchored gelatin matrix successfully. Due to its high biocompatibility, gelatin is very suitable as a stabilizing agent and despite other organic capping agents, it reduces the toxicity of these Au nanoparticles (Au Nps). These nanomaterials have been studied using Fourier transformed infrared (FT-IR), Optical Absorption, Photoluminescence (PL) spectroscopy techniques, using transmission electron microscope (TEM) and X ray diffraction (XRD). And influence of different concentrations of reducing agent have been investigated in preparation and optical properties of Au Nanoparticles with Gelatin as a capping agent. These nanomaterials are very promising for making devices with high luminosity in nano dimensions. In addition, since non -toxic and solvent materials are used in synthesis, the integration of these particles into a variety of systems, especially those related to biological and biomedical applications, can be practical and useful.

Unwanted electromagnetic wave interference poses significant challenges in military and industrial contexts, prompting extensive research into electromagnetic interference shielding materials, particularly radar absorbing coatings. Materials with inherent dielectric or magnetic properties, such as magnetite and polymers, have proven effective in wave absorption, alongside investigations into metals and carbon-based materials. Nevertheless, reduced graphene oxide (RGO) presents a drawback due to its suboptimal impedance matching. To address this limitation, researchers have explored the enhancement of impedance matching by incorporating RGO with magnetic materials. Emerging as promising candidates are ternary and quaternary nanocomposites, including conducting polymers, offering the potential to effectively absorb microwave and radio waves. This study focuses on RGO/Fe3O4 nanoporous composites incorporating polyaniline. These composites exhibit remarkable capabilities in the absorption of electromagnetic waves, coupled with a straightforward synthesis process. The study makes a significant contribution to the realm of electromagnetic interference shielding materials, underscoring the considerable promise held by RGO/Fe3O4/PANI composites.

Starch and its derivatives have proven their usefulness in flocculation processes. Among these derivatives, cationic starch has been widely used in the water treatment industry as a suspending agent and surface absorption processes. Cationic starch is synthesized by adding chemical materials with certain cationic groups to natural starch. Cationic starches have long been used as additives in papermaking to improve mechanical strength and provide better and faster shelf-life properties. This review briefly discusses the recent studies on the synthesis, structure and mechanism of surface adsorption in cationic starch flocculants. The most important use of flocculants is in water purification. Water treatment facilities use coagulants to neutralize charged particles suspended in water. This study also describes conventional synthetic processes and cation substitutions of cationic starches and addresses their current and potential applications in flocculation. In addition, the effect of structural and operational parameters on the mechanism and extent of cationic starch surface absorption has been investigated, especially in the case of microorganisms. All the mentioned studies have been investigated with the aim of expressing the high ability of cationic starches in the direction of flocculation and wastewater treatment with efficient and cost-effective performance.

Efficient microwave absorbing materials are critical for a variety of applications ranging from military aircraft to communications equipment. Addressing the challenges in reducing S-band (2-8 GHz) waves, this research focused on the development of high-performance microwave absorber materials and investigating the potential of graphene in combination with magnetic elements. Cobalt ferrite, known for its promising magnetic properties, forms the basis of these composites. However, the inherent limitations of pure CoFe2O4 led to the investigation of new approaches, including the incorporation of graphene derivatives such as reduced graphene oxide (rGO) and conductive polymers such as polyaniline. This synthesis included combining iron salts, cobalt sources and rGO, optimizing specific chemical reactions to produce rGO/CoFe2O4 and rGO/CoFe2O4/PANI composites. Structural analysis through different techniques showed the presence of distinct functional groups, the morphology of the composites, their thermal and magnetic behaviors. Analysis of microwave absorption highlighted the effectiveness of the composite, especially at 7 GHz, in minimizing the reflection of electromagnetic waves. Also, the presence of polyaniline significantly increased the electrical permeability of the composite and contributed to the effective absorption of microwaves due to the appropriate matching of the composite resistance. In conclusion, the synthesized rGO/CoFe2O4/PANI composite showed exceptional potential as an efficient microwave absorber material in the S-band range. This innovative ternary composite paves the way for advanced applications in diverse fields where attenuation of electromagnetic waves is important.

Mucin proteins are essential components of the human respiratory system, playing a crucial role in maintaining controlled permeability through the formation of a reticulated structure and electrical charge (exhibiting high surface activity). In addition to their defensive function against external elements, mucins contribute to the dynamic equilibrium in the upper respiratory tract. This study investigates the role of electrical charge in the performance of mucin proteins by introducing and utilizing the drop profile tensiometry method to measure dynamic surface tension and surface elasticity across a wide range of mucin protein concentrations (ranging from 1 to 1000 nanomolar) in buffered solutions. The measurement results of dynamic surface tension indicate a high absorption rate of these large-molecule proteins at the air-water interface for concentrations exceeding one hundred nanomolar. This observation highlights the rapid formation of a structured protective layer in the respiratory system. The measurement of surface elasticity parameters, utilizing interfacial oscillations at different frequencies, demonstrates elevated values of elasticity within the absorbed structured layer.