Current Materials Science - Volume 16, Issue 3, 2023

Different electromagnetic interference (EMI) shielding materials have been developed over time. In the past electromagnetic (EM) shielding technology made use of metals and their composites because of good shielding effectiveness but their low elasticity high density and corrosion tendency render them obsolete. Ceramic-based composites have also gained popularity for EMI shielding applications because of their low density and excellent corrosion resistance but high absorption loss is a major drawback. Recently, polymer-based composites have attracted attention because they make for superb EMI shielding with the advantages of electromagnetic wave absorption over reflection and have been widely used with fast growth in application after their emergence. This paper reviews the progress of polymer-based composites as efficient materials for electromagnetic interference shielding and applications. Electromagnetic (EM) waves are formed by the interaction of an electric field and a magnetic field. EM waves require no specific medium through which they can move. Their movement can be though air solid materials liquid or even vacuum. The EM spectrum ranges from lower energy waves (longer wavelengths) such as radio waves and microwaves to higher energy waves (shorter wavelengths), such as gamma rays and X-rays. Traditional materials such as metals and ceramics were found to be useful as EMI shielding materials. However, low elasticity high density and high absorption loss tend to limit their EMI effectiveness. Recently polymer-based electromagnetic shielding materials have been widely employed as EMI shielding materials. Given the above different EMI shielding materials based on diverse matrix materials are discussed with emphasis on polymer-based composites as emerging and alternative EMI shielding materials. The development of the electronic industry offers weight reduction as an additional technical requirement besides good EMI shielding performance. EMI shielding ensures the inhibition of the transmission of EM waves from one point to another using shield materials. Metals as conventional EMI shielding materials have been substituted with alternative materials which are lighter such as polymer-based materials and ceramic-based materials.

Over the last few years, research on catechol-containing polymers has focused mainly on making mussel-inspired catechol-containing polymers and examining their adhesion ability onto various substrata under dry and wet conditions. Indeed, a surge of dopamine-bearing vinylic monomers such as dopamine acrylates and their protected ones have been homopolymerized or copolymerized with fittingly chosen comonomers for targeted applications. Novel polymerization methods such as RAFT and ATRP have been gratifyingly employed to realize these polymers with controlled molecular weights and polydispersity indexes. The protection of hydroxyl groups of the dopamine-based vinyl derivatives has been achieved with different groups, namely, alkyl, benzyl, acetal, silyl, and ester. Nevertheless, in several cases, the unprotected dopamine-based vinylic monomers have been unprecedentedly shown to undergo polymerization with no inhibition or retardation. Ring-opening polymerization has been applied to copolymerizing several oxiranecontaining dopamine monomers and catechol-containing monomers with cyclic comonomers with no major difficulty. Polymers from this method exhibited excellent scaffolds for preparing various materials with desired functions such as electronic conductivity and adhesion to a wide range of objects. Catechol and catechol-containing molecules have been subjected to polycondensation with a number of comonomers, such as formaldehyde, polyamines, polyols, and polyacids, polyisocyanates, under special conditions. These polycondensation resins have been evaluated mainly for their adsorption capacity towards heavy metals and dyes for wastewater decontamination. Proteins antifouling properties of some of these resins have been demonstrated as well. Their special chemistry allowed their use in realizing metal nanoparticles for different purposes.

Background: Polysaccharides are a type of natural macromolecular polymer that can be found in plants, animals, fungi, algae, and marine organisms. Its activities have piqued the interest of researchers. The internal structure, as well as their chemical and physical properties, dictate how they work. Polysaccharide functionalities are progressively being chemically changed. Using this approach, polysaccharides' structural, physicochemical, and biological properties can all be altered. Aim and Methods: The review sought to provide an overview of polysaccharide modification but also biological use. Recent research has shown that chemically modifying polysaccharides may increase their immunological function as well as their antiviral, antibacterial, antioxidant, as well as other characteristics. There are several chemical modifications, including sulfation, carboxymethylation, acetylation, phosphorylation, and others. Modified polysaccharide recent developments are reviewed. Discussion and Results: Polysaccharide physiochemical properties and biological activity can change as their structural properties change. The structural modifications that occur depend on the source of the polysaccharides. Chemical modification has enormous promise for enhancing biomedical applications. These modified polysaccharides have made significant contributions to tissue engineering and drug delivery applications. Modification of polysaccharides induces therapeutic benefits. The immunomodulation of polysaccharides and their derivatives, as well as their chemical modification, has been studied and discussed. Conclusion: These modified polysaccharides have the potential to be used for wound dressing, gene delivery, drug delivery, etc.

Background: Laser additive manufacturing has been used for surface repair and remanufacturing due to fast laser processing speed, high energy density, and dense microstructure. However, the properties of coating samples produced by laser additive manufacturing of ironbased alloys vary considerably, resulting in a large amount of data that needs to be accumulated and analyzed. Methods: The coating properties of iron-based alloy powders manufactured by laser cladding are studied. The optimal process parameters of the laser cladding are determined by exploring and comparing the macroscopic appearance, hardness, and conductivity of the junction of the cladding. Results: From the macroscopic appearance, when the ratio of the height to the width of the cladding layer is 3.615, the surface of the cladding layer has a smooth surface and is closely combined with the substrate. Conclusion: The hardness of the cladding layer is found to increase significantly, with an average hardness of 663 HV. Besides, it is found that the blackhead's hole causes the conductivity change. The ratio of the largest hole area to the smallest hole area is 8.29 times, and the depth ratio is 1.91 times, but the average resistance ratio is about 1.6 times.