Chitosan-doped-hybrid/TiO 2 nanocomposite based sol-gel coating for the corrosion resistance of aluminum metal in 3.5% NaCl medium

Corrosion Rate and Mechanism of Degradation of Chitosan/TiO2 Coatings Deposited on MgZnCa Alloy in Hank's Solution

Overly fast corrosion degradation of biodegradable magnesium alloys has been a major problem over the last several years. The development of protective coatings by using biocompatible, biodegradable, and non-toxic material such as chitosan ensures a reduction in the rate of corrosion of Mg alloys in simulated body fluids. In this study, chitosan/TiO2 nanocomposite coating was used for the first time to hinder the corrosion rate of Mg19Zn1Ca alloy in Hank's solution. The main goal of this research is to investigate and explain the corrosion degradation mechanism of Mg19Zn1Ca alloy coated by nanocomposite chitosan-based coating. The chemical composition, structural analyses, and corrosion tests were used to evaluate the protective properties of the chitosan/TiO2 coating deposited on the Mg19Zn1Ca substrate. The chitosan/TiO2 coating slows down the corrosion rate of the magnesium alloy by more than threefold (3.6 times). The interaction of TiO2 (NPs) with the hydroxy and amine groups present in the chitosan molecule cause their uniform distribution in the chitosan matrix. The chitosan/TiO2 coating limits the contact of the substrate with Hank's solution.

Thermal and biological properties of novel sodium carboxymethylcellulose-PPFMA nanocomposites containing biosynthesized Ag-ZnO hybrid filler

The aim of this study was to produce new nanocomposites with antimicrobial, antioxidant and anticancer properties that can be used in biomedical research based on carboxymethyl cellulose (NaCMC) biopolymer. First, poly(2-oxo-2-(pentafluorophenoxy)ethyl-2-methylprop-2-enoate) (PPFMA) was synthesized and characterized by FTIR and NMR techniques. It was then blended with NaCMC by in situ/hydrothermal method to produce a semi-synthetic functional material. Changes in the FTIR data of the blend and the single Tg value from DSC confirmed the compatibility of the blend. To enhance the thermal and biological properties of the NaCMC-PPFMA blend, biosynthesized Ag-ZnONPs were hydrothermally incorporated into the blend at different weight ratios. The prepared materials were characterized by SEM, EDX, TEM, XRD and FTIR. The thermal stability of the materials was determined by thermogravimetric analysis (TGA), and glass transition temperatures (Tg) was determined by differential scanning calorimeter (DSC). The oxidant, antioxidant, antimicrobial, and cytotoxic properties of PPFMA, Ag-ZnONPs, PPFMA-NaCMC blend, and nanocomposites were investigated in detail. The total oxidant state (TOS) value of the NaCMC-PPFMA blend, which was 0.72 μmol equivalent H2O2/L, increased to 7.2-10.4 μmol equivalent H2O2/L with the addition of Ag-ZnONPs. Ag-ZnONPs decreased total antioxidant state (TAS) levels of the nanocomposites while increasing their oxidant activity. Therefore, an increase in the antimicrobial activity of the nanocomposites was observed. Adding Ag-ZnONPs to the NaCMC-PPFMA blend increased the thermal stability by 22 °C and the Tg value by 9 °C. Finally, the potential of Ag-ZnONPs containing nanocomposites in wound healing therapies was examined. The findings suggest that nanocomposites prepared by incorporating Ag-ZnONPs into the semi-synthetic NaCMC-PPFMA blend can be a source of bio-safe raw materials and can be used as potential wound healers.

Chitosan Nanocomposites as Wound Healing Materials: Advances in Processing Techniques and Mechanical Properties

This review discusses the increasing potential of chitosan nanocomposites as viable materials capable of targeting these debilitating factors. This review focuses on various techniques used to process chitosan nanocomposites and their mechanical properties. Chitosan nanocomposites are regarded as highly effective antimicrobials for the treatment of chronic wounds. Chitosan nanocomposites, such as chitosan/polyethylene and oxide/silica/ciprofloxacin, demonstrate efficient antibacterial activity and exhibit no cytotoxicity against Human Foreskin Fibroblast Cell Lines (HFF2). Other studies have also showcased the capacity of chitosan nanocomposites to accelerate and improve tissue regeneration through increment in the number of fibroblast cells and angiogenesis and reduction of the inflammation phase. The layer-by-layer technique has benefits, ensuring its suitability in preparing chitosan nanocomposites for drug delivery and wound dressing applications. While the co-precipitation route requires a cross-linker to achieve stability during processing, the solution-casting route can produce stable chitosan nanocomposites without a cross-linker. By using the solution casting method, fillers such as multi-walled carbon nanotubes (MWCNTs) and halloysite nanotubes (HTs) can be uniformly distributed in the chitosan, leading to improved mechanical properties. The antibacterial effects can be achieved with the introduction of AgNPs or ZnO. With the increasing understanding of the biological mechanisms that control these diseases, there is an influx in the introduction of novel materials into the mainstream wound care market.

Metals and metal oxides polymer frameworks as advanced anticorrosive materials: design, performance, and future direction

Metals (Ms) and metal oxides (MOs) possess a strong tendency to coordinate and combine with organic polymers to form respective metal–polymer frameworks (MPFs) and metal oxide polymer frameworks (MOPFs). MPFs and MOPFs can be regarded as composites of organic polymers. MPFs and MOPFs are widely used for industrial and biological applications including as anticorrosive materials in the aqueous phase as well as in the coating conditions. The presence of the Ms and MOs in the polymer coatings improves the corrosion inhibition potential of MPFs and MOPFs by improving their self-healing properties. The Ms and MOs fill the micropores and cracks through which corrosive species such as water, oxygen, and corrosive ions and salts can diffuse and destroy the coating structures. Therefore, the Ms and MOs enhance the durability as well as the effectiveness of the polymer coatings. The present review article is intended to describe the corrosion inhibition potential of some MPFs and MOPFs of some most frequently utilized transition metal elements such as Ti, Si, Zn, Ce, Ag, and Au. The mechanism of corrosion inhibition of MPFs and MOPFs is also described in the presence and absence of metal and metal oxides.

3-Mercaptopropanoic Acid-Doped Chitosan/Hybrid-Based Multilayer Sol-Gel Coatings for Cu Protection in 3.5% NaCl Solution

In this work, biopolymer based sol-gel was synthesized by doping 3-mercaptopropanoic acid (MPA) with chitosan and a hybrid of 3-glycidoxypropyltrimethoxysilane (GPTMS) and tetraethoxysilane (TEOS). Prepared MPA/hybrid-doped chitosan was applied toa copper (Cu) metal surface by the self-assembly technique to protect the Cu metal from corrosion in a 3.5% NaCl solution. The structure, mechanism and morphology of the modified electrodes were examined using Fourier transform infra-red (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDX), and atomic force microscopy (AFM). The decrease in surface roughness for Hy/chitosan/MPA-coated Cu indicates the formation of a dense layer on Cu metal confirmed by AFM. The corrosion protection evaluation of sol-gel coated electrodes was analyzed using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization studies (PDS) in a 3.5% NaCl medium. The MPA/hybrid-doped chitosan sol-gel coated Cu metal showed the greatest resistance to corrosionthanother sol-gel modified electrodes. The MPA-doped-chitosan/Hy sol-gel coating protected the Cu metal by an anodic dissolution process and improved its corrosion protection to 99.9%.

Chitosan derivative corrosion inhibitor for aluminum alloy in sodium chloride solution: A green organic/inorganic hybrid

A novel and eco-friendly chitosan derivative was synthesized as green corrosion inhibitors on C3003 aluminum alloy in 3.5 wt.% NaCl solution. In this paper, CP was prepared by Schiff Base reaction with chitosan and 4-pyridinecarboxaldehyde. Then, TiO₂ was dispersed in CP to prepare CPT nanocomposite. The corrosion inhibition effect of CPT on C3003 aluminum alloy at different concentrations were studied with electrochemical techniques and surface analysis. The results showed that the maximum inhibition efficiency of CPT nanocomposite reaches to 94.5 % at 200 ppm after the immersed in 3.5 wt.% NaCl solution for 72 h. Meanwhile, the contact angle increases to 120° due to the formation of hydrophobic substances. The strategy of organic/inorganic hybrid can provide the inspiration for the development of chitosan corrosion inhibitor with low concentration and high efficiency.

An antimony based organic-inorganic hybrid coating material with high quantum efficiency and thermal quenching effect

An antimony based luminescent organic-inorganic hybrid compound H₃SbCl₆(L)₆ (1, L = 2-(3-methyl-1H-imidazol-3-ium-1-yl)acetate) has been prepared by the solvothermal method. It emits bright green light peaking at 525 nm, with an internal quantum yield (IQY) of 73% under 360 nm excitation. The negative thermal quenching (NTQ) effect has been observed in the temperature range of 77 K to 297 K. Due to its ionic structure, compound 1 is soluble in numerous organic solvents, including methanol, dimethyl sulfoxide (DMSO), etc. The solution processability combined with high quantum efficiency makes 1 a promising candidate as a luminescent coating material for optoelectronic devices.

Polymer Nanocomposite-based Coatings for Corrosion Protection

Corrosion of metals induces enormous loss of material performance and increase of cost, which has been a common and intractable issue that needs to be addressed urgently. Coating technology has been acknowledged to be the most economic and efficient approach to retard the metal corrosion. For several decades, polymers have been recognized as an effective anticorrosion coating material in both industries and scientific communities, as they demonstrate good barrier properties, ease of altering properties and massive production. Nanomaterials show distinctively different physical and chemical properties compared with their bulk counterparts, which have been considered as highly promising functional materials in various applications, impacting virtually all the fields of science and technologies. Recently, the introduction of nanomaterials with various properties into polymer matrix to form a polymer nanocomposite has been devoted to improve anticorrosive ability of polymer coatings. In this review article, we highlight the recent advances and synopsis of these high-performance polymer nanocomposites as anticorrosive coating materials. We expect that this work could be helpful for the researchers who are interested in the development of functional nanomaterials and advanced corrosion protection technology.

Effects of Different TiO2 Nanoparticles Concentrations on the Physical and Antibacterial Activities of Chitosan-Based Coating Film

In this investigation, the effect of different concentrations of titanium dioxide (TiO₂) nanoparticles (NPs) on the structure and antimicrobial activity of chitosan-based coating films was examined. Analysis using scanning electron microscopy (SEM) and atomic force microscopy (AFM) revealed that the modified TiO₂ NPs were successfully dispersed into the chitosan matrix, and that the roughness of the chitosan-TiO₂ nanocomposites were significantly reduced. Moreover, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses indicated that the chitosan interacted with TiO₂ NPs and possessed good compatibility, while a thermogravimetric analysis (TGA) of the thermal properties showed that the chitosan-TiO₂ nanocomposites with 0.05% TiO₂ NPs concentration had the best thermal stability. The chitosan-TiO₂ nanocomposite exhibited an inhibitory effect on the growth of Escherichia coli and Staphylococcus aureus. This antimicrobial activity of the chitosan-TiO₂ nanocomposites had an inhibition zone ranging from 9.86 ± 0.90 to 13.55 ± 0.35 (mm). These results, therefore, indicate that chitosan-based coating films incorporated with TiO₂ NPs might become a potential packaging system for prolonging the shelf-life of fruits and vegetables.

Chitosan-TiO2: A Versatile Hybrid Composite

In recent years, a strong interest has emerged in hybrid composites and their potential uses, especially in chitosan–titanium dioxide (CS–TiO₂) composites, which have interesting technological properties and applications. This review describes the reported advantages and limitations of the functionalization of chitosan by adding TiO₂ nanoparticles. Their effects on structural, textural, thermal, optical, mechanical, and vapor barrier properties and their biodegradability are also discussed. Evidence shows that the incorporation of TiO₂ onto the CS matrix improves all the above properties in a dose-dependent manner. Nonetheless, the CS–TiO₂ composite exhibits great potential applications including antimicrobial activity against bacteria and fungi; UV-barrier properties when it is used for packaging and textile purposes; environmental applications for removal of heavy metal ions and degradation of diverse water pollutants; biomedical applications as a wound-healing material, drug delivery system, or by the development of biosensors. Furthermore, no cytotoxic effects of CS–TiO₂ have been reported on different cell lines, which supports their use for food and biomedical applications. Moreover, CS–TiO₂ has also been used as an anti-corrosive material. However, the development of suitable protocols for CS–TiO₂ composite preparation is mandatory for industrial-scale implementation.

Accumulation of 2-Acetylamino-5-mercapto-1,3,4-thiadiazole in chitosan coatings for improved anticorrosive effect on zinc

Chitosan (Chit) coatings were applied on zinc substrates by the dip-coating method. Subsequently, the coatings were impregnated with a corrosion inhibitor, 2-Acetylamino-5-mercapto-1,3,4-thiadiazole (AcAMT) to obtain an increased anticorrosive effect. The coating thickness and the AcAMT accumulation were determined using UV-Vis spectroscopy on glass and quartz substrates, respectively. The surface morphology and coverage were investigated with atomic force microscopy. Electrochemical impedance spectroscopy and potentiodynamic polarization techniques were used to investigate the protective properties of the impregnated coatings. The chitosan coatings facilitated the accumulation of the corrosion inhibitor inside the polymeric matrix (a multiplication of 380 times compared to the impregnating solution concentration was calculated), channeling high amounts of AcAMT to the Zn surface, which resulted in an inhibition efficiency of >90%. This effect demonstrates the applicability of chitosan coatings as carriers for corrosion inhibitors, significantly reducing the amount of inhibitor needed to achieve good anticorrosive effects.

Microbiologically influenced corrosion mechanism of 304L stainless steel in treated urban wastewater and protective effect of silane-TiO2 coating

Microbiologically influenced corrosion (MIC) of bare and silane-TiO₂ sol-gel coated stainless steel (SS) was studied in treated urban wastewater (TUWW). Combining the electrochemical impedance spectroscopy (EIS) and the scanning vibrating electrode technique (SVET) showed that SS surface colonization occurs, at earlier stages, by iron-oxidizing bacteria (IOB), and later by sulphate-reducing bacteria (SRB). The SVET results showed that chemical corrosion process and bacterial respiration led to the depletion of dissolved oxygen, creating a differential aeration cell and thus a localized corrosion phenomenon. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) showed that the growth of a bacterial biofilm on 304L SS was a dynamic process, stimulating the localized oxidation of SS. To improve corrosion protection, a silane-TiO₂ sol-gel coating for SS is proposed. SEM showed that the coating reduced bacterial adhesion and EIS study demonstrated that the coating improved the barrier properties and corrosion resistance of 304L SS in TUWW over a short period of immersion.

Thermal and Rheological Study of Nanocomposites, Reinforced with Bi-Phase Ceramic Nanoparticles

In this study the synthesis of bi-phase nanoparticles of Fe1.46Zn0.5La0.04Cu0.5O4 (FZLCs) ceramics were first carried out by Sol-gel method and then nanocomposites of FZLCs with polyvinyl pyrrolidone (PVP), polyvinyl alcohol (PVA), polyethylene glycol (PEG) and polyethylene oxide (PEO) were prepared by one-pot blending technique. XRD, FT-IR, TG/DTA and SEM techniques were applied for complete characterization of composites. Rheological and dielectric properties of all nanocomposites were studied in detail for their comparative performance. TGA results reveal the highly thermal stability for all nanocomposites in this order i.e. FLZCs/PEO > FLZCs/PVA > FZLCs/PVP > FZLCs/PEG. Rheological properties show that these materials are rigid, pseudo plastic and non-Newtonian in nature. The increase in values for storage modulus (G′) and loss modulus (G′′) with increasing angular frequency owed to the shear thinning behavior of these nanocomposites. Dielectric properties show good agreement to that of energy storage substances which means that these materials have potential to be applied in storage devices.

Newly synthesized quercetin derivatives as corrosion inhibitors for mild steel in 1 M HCl: combined experimental and theoretical investigation

To evaluate the corrosion inhibition efficacy of the derivatives of naturally available organics, mono and di-4-((2-hydroxyethyl)piperazin-1-yl)methyl derivatives of quercetin, a flavonoid, have been synthesized.