Modification of palm fiber with chitosan-AESO blend coating

Natural fibers are available as an essential substitute for synthetic fiber in many applications. However, the sensitivity of Chinese Windmill Palm or Trachycarpus Fortune Fiber (TFF) to water causes low interfacial bonding between the matrix and the fiber and at the end reduces the mechanical properties of the composite product. Alkaline treatment improves mechanical properties and does not affect water absorption. Hence, additional treatment in the coating is required. This study uses alkaline treatment and coating modification using blended chitosan and Acrylated Epoxidized Soybean Oil (AESO). Blend coating between AESO and chitosan is performed to increase water absorption and mechanical properties. TFF water resistance improved significantly after the coating, with water absorption of the alkaline/blend coating-TFF of 3.98 % ± 0.52 and swell ability of 3.156 % ± 0.17. This indicated that blend coating had formed a cross-link of fiber and matrix after alkalization. Thus, the single fiber tensile strength increased due to the alkaline treatment, and water absorption decreased due to the coating. The combination of alkaline treatment and blend coating on TFF brings excellent properties, as shown by the increase in tensile strength in both single fiber test and composite.

Enhanced Coating Protection of C-Steel Using Polystyrene Clay Nanocomposite Impregnated with Inhibitors

Polymer-Clay Nanocomposite (PCN) coatings were prepared using the solution intercalation method. The raw Khulays clay was treated with NaCl to produce sodium clay (NaC). Thereafter, Cetyl Pyridinium Chloride (CPC) was used to convert NaC into the organic clay form (OC). PCN was prepared by adding polystyrene as the matrix to different weights of OC to prepare 1 wt.% and 3 wt.% PCN. To enhance the coating protection of C-steel in NaCl solution, PCN coatings were added to microcapsules loaded with some corrosion inhibitors PCN (MC). The microcapsules are prepared by the encapsulation of rare-earth metal Ce⁺³ ions and Isobutyl silanol into polystyrene via the Double Emulsion Solvent Evaporation (DESE) technique. Characterization techniques such as FTIR, X-Ray Diffraction (XRD), and Transmission Electron Microscopy (TEM) were employed. FTIR confirmed the success of the preparation, while XRD and TEM revealed an intercalated structure of 1 wt.% PCN while 3 wt.% PCN has a fully exfoliated structure. Electrochemical Impedance Spectroscopy (EIS), Electrochemical Frequency Modulation (EFM), and Potentiodynamic Polarization showed an enhanced protection efficiency of PCN (MC) coatings. The results demonstrated that the corrosion resistance (R_Corr) of 3% PCN (MC) coating was higher than all the formulations. These PCN (MC) coatings may provide corrosion protection for C-steel pipes in many industrial applications.

Progress in bioactive surface coatings on biodegradable Mg alloys: A critical review towards clinical translation

Mg and its alloys evince strong candidature for biodegradable bone implants, cardiovascular stents, and wound closing devices. However, their rapid degradation rate causes premature implant failure, constraining clinical applications. Bio-functional surface coatings have emerged as the most competent strategy to fulfill the diverse clinical requirements, besides yielding effective corrosion resistance. This article reviews the progress of biodegradable and advanced surface coatings on Mg alloys investigated in recent years, aiming to build up a comprehensive knowledge framework of coating techniques, processing parameters, performance measures in terms of corrosion resistance, adhesion strength, and biocompatibility. Recently developed conversion and deposition type surface coatings are thoroughly discussed by reporting their essential therapeutic responses like osteogenesis, angiogenesis, cytocompatibility, hemocompatibility, anti-bacterial, and controlled drug release towards in-vitro and in-vivo study models. The challenges associated with metallic, ceramic and polymeric coatings along with merits and demerits of various coatings have been illustrated. The use of multilayered hybrid coating comprising a unique combination of organic and inorganic components has been emphasized with future perspectives to obtain diverse bio-functionalities in a facile single coating system for orthopedic implant applications.

Enhancement of Cerium Sorption onto Urea-Functionalized Magnetite Chitosan Microparticles by Sorbent Sulfonation—Application to Ore Leachate

The recovery of strategic metals such as rare earth elements (REEs) requires the development of new sorbents with high sorption capacities and selectivity. The bi-functionality of sorbents showed a remarkable capacity for the enhancement of binding properties. This work compares the sorption properties of magnetic chitosan (MC, prepared by dispersion of hydrothermally precipitated magnetite microparticles (synthesized through Fe(II)/Fe(III) precursors) into chitosan solution and crosslinking with glutaraldehyde) with those of the urea derivative (MC-UR) and its sulfonated derivative (MC-UR/S) for cerium (as an example of REEs). The sorbents were characterized by FTIR, TGA, elemental analysis, SEM-EDX, TEM, VSM, and titration. In a second step, the effect of pH (optimum at pH 5), the uptake kinetics (fitted by the pseudo-first-order rate equation), the sorption isotherms (modeled by the Langmuir equation) are investigated. The successive modifications of magnetic chitosan increases the maximum sorption capacity from 0.28 to 0.845 and 1.25 mmol Ce g−1 (MC, MC-UR, and MC-UR/S, respectively). The bi-functionalization strongly increases the selectivity of the sorbent for Ce(III) through multi-component equimolar solutions (especially at pH 4). The functionalization notably increases the stability at recycling (for at least 5 cycles), using 0.2 M HCl for the complete desorption of cerium from the loaded sorbent. The bi-functionalized sorbent was successfully tested for the recovery of cerium from pre-treated acidic leachates, recovered from low-grade cerium-bearing Egyptian ore.

Potential Impacts of Prunus domestica Based Natural Gum on Physicochemical Properties of Polyaniline for Corrosion Inhibition of Mild and Stainless Steel

The lack of an eco-friendly approach towards application of polyaniline as a coating material has been one of the most challenging tasks. Herein, the synthesis of green Prunus domestica gum grafted polyaniline (PDG-g-PANI) composite is reported by a cost-effective emulsion polymerization for application as an efficient anti-corrosion material for mild steel (MS) and stainless steel (SS) in a strong corroding environment. The composite formation was confirmed by Ultraviolet Visible (UV-Visible) and Fourier Transformed Infrared (FTIR) spectroscopies. X-ray diffraction data revealed the amorphous nature of the PDG-g-PANI. Scanning Electron Microscopic (SEM) images showed a bi-layered structure having a parent porous layer of PANI coated with afibrous layer of PDG. The solubility test confirmed the dissolution of PDG-g-PANI in common organic solvents such as acetone, ethanol, propanol, butanol, chloroform, N-Methyl-2-pyrrolidone, dimethyl sulfoxide, and the mixture of propanol and chloroform. The polarization curve, open circuit potential, electrochemical impendence spectroscopy (EIS), and gravimetric analysis were applied to investigate the corrosion protection behavior of the composite on MS and SS in 3.5% NaCl and 1 M H₂SO₄ solution. The PDG-g-PANI-coated MS exhibited 96% corrosion inhibition efficiency as compared to 86% and 43% for pristine PANI and PDG in 3.5% NaCl solution while PDG-g-PANI-coated SS showed 98% corrosion inhibition efficiency. Moreover, 99% and 96.6% corrosion protection was observed for PDG-g-PANI-coated MS and SS in 1 M H₂SO₄ solution. Gravimetric studies revealed that PDG-g-PANI coating can protect MS up to 93% for 14 days in salt solution while 97% corrosion inhibition efficiency was retained for 2 months in open air.

Experimental and In-Silico Computational Modeling of Cerium Oxide Nanoparticles Functionalized by Gelatin as an Eco-Friendly Anti-Corrosion Barrier on X60 Steel Alloys in Acidic Environments

An eco-friendly and a facile route successfully prepared novel cerium oxide nanoparticles functionalized by gelatin. The introduced CeO₂@gelatin was investigated in terms of FE-SEM, EDX, TEM, chemical mapping, FT-IR, and (TGA) thermal analyses. These characterization tools indicate the successful synthesis of a material having CeO₂ and gelatin as a composite material. The prepared composite CeO₂@gelatin was used as an environment-friendly coated film or X60 steel alloys in acidizing oil well medium. Moreover, the effect of CeO₂ percent on film composition was investigated. LPR corrosion rate, E_ocp-time, EIS, and PDP tools determined the corrosion protection capacity. The CeO₂@gelatin composite exhibited high protection capacity compared to pure gelatin; in particular, 5.0% CeO₂@gelatin coating film shows the highest protection capacity (98.2%), with long-term anti-corrosive features. The % CeO₂@gelatin-coated films formed the protective adsorbed layer on the steel interface by developing a strong bond among nitrogen atoms in the CeO₂@gelatin film and the electrode interface. Surface morphology using FESEM measurements confirmed the high efficiency of the fabricated CeO₂@gelatin composite on the protection X60 steel alloys. DFT calculations and MC simulations were explored to study the relations between the protection action and the molecular construction of the coated systems, which were in good alignment with the empirical findings.

Core@shell structured ceria@mesoporous silica nanoantibiotics restrain bacterial growth in vitro and in vivo

Due to its modular and flexible design options, mesoporous silica provides ample opportunities when developing new strategies for combinatory antibacterial treatments. In this study, antibacterial ceria (CeO₂) nanoparticles (NP) were used as core material, and were further coated with a mesoporous silica shell (mSiO₂) to obtain a core@shell structured nanocomposite (CeO₂@mSiO₂). The porous silica shell was utilized as drug reservoir, whereby CeO₂@mSiO₂ was loaded with the antimicrobial agent capsaicin (CeO₂@mSiO₂/Cap). CeO₂@mSiO₂/Cap was further surface-coated with the natural antimicrobial polymer chitosan by employing physical adsorption. The obtained nanocomposite, CeO₂@mSiO₂/Cap@Chit, denoted NAB, which stands for "nanoantibiotic", provided a combinatory antibacterial mode of action. The antibacterial effect of NAB on the Gram-negative bacteria Escherichia coli (E.coli) was proven to be significant in vitro. In addition, in vivo evaluations revealed NAB to inhibit the bacterial growth in the intestine of bacteria-fed Drosophila melanogaster larvae, and decreased the required dose of capsaicin needed to eliminate bacteria. As our constructed CeO₂@mSiO₂ did not show toxicity to mammalian cells, it holds promise for the development of next-generation nanoantibiotics of non-toxic nature with flexible design options.

Corrosion Resistance of Epoxy Coatings Modified by Bis-Silane Prepolymer on Aluminum Alloy

In this communication, a bis-silane prepolymer was used to modify epoxy resin, aiming to enhance the corrosion resistance of epoxy coatings on aluminum alloy substrates. The bis-silane prepolymer was prepared by tetraethoxysilane (TEOS) and γ-glycidoxypropyl trimethoxysilane (GPTMS). The corrosion behavior of silane-epoxy coatings was studied. Compared with silane monomer-modified epoxy coatings, bis-silane-modified epoxy coatings have lower coating capacitance (Cc), higher charge transfer resistances (Rdl), and lower double layer capacitance (Cdl) during long-time immersion. It indicates that bis-silane-modified epoxy coating has stronger waterproof permeability and substrate corrosion protection ability. In addition, due to the leaching of the silane component and cross-linking reaction between different silanes during the immersion process, the bis-silane-modified epoxy coatings exhibit much stronger “self-healing” ability.

Corrosion inhibition potential of chitosan based Schiff bases: Design, performance and applications

Chemically, chitosan is a linear polysaccharide constituted of arbitrarily distributed D-glucosamine and N-acetyl-D-glucosamine constituents combined together via β-1,4-glycosidic linkage. Because of increasing ecological awareness and strict environmental regulations, species of natural and biological origin such as chitosan can be identified as ideal environmental sustainable alternative to replace traditional heterocyclic (toxic) corrosion inhibitors. Although, chitosan contains numerous electron rich sites however chitosan itself is not highly effective aqueous phase corrosion inhibitors. Aqueous phase application of chitosan is limited because of its limited solubility. However, chemically modified chitosan derivatives, such as chitosan based Schiff bases (CSBs) exhibit remarkable solubility in such electrolytes. Therefore, recently various reports dealing with the anticorrosion potential of CSBs have been reported. Present review article describes the collections on CSBs as aqueous phase corrosion inhibitors. Nature of CSBs adsorption through chelation (coordination) has also been discussed based on literature outcomes.

Modified Epoxy with Chitosan Triazine Dihydrazide Derivatives for Mechanical and Corrosion Protection of Steel

Modification of the curing exothermic reaction of epoxy resin with polyamine (PA) hardeners by new chemically bonded fillers to improve the mechanical properties and anticorrosion performances of the epoxy coatings is the main goal for wide applications of epoxy coatings. In this work, the chemical structure of chitosan was modified with triazine hydrazide moiety that contains primary, secondary, and tertiary amine groups to act as activator and dangling chain linkers during the curing of epoxy/PA system. Different molecular masses of chitosan were modified with triazine dihydrazide moiety (Ch-TH2), and their chemical structures and surface morphologies were identified. Their thermal stabilities were investigated, and the grafting percentages with triazine hydrazide were determined from thermal analysis. Different weight percentages of Ch-TH2 ranged from 1 to 10 Wt. % were added to the epoxy/PA system, and their curing characteristics, such as heat enthalpy and glass transition temperature, were determined from non-isothermal dynamic scanning calorimetric thermograms. The effects of molecular masses, triazine dihydrazide %, and Ch-TH2 Wt. % on the mechanical, adhesion and anticorrosive properties of the cured epoxy/PA coatings for steel were investigated. The optimum Ch-TH2 Wt. % was selected from 3 to 6 Wt. % to improve the mechanical, adhesion, and anticorrosive properties of the cured epoxy/PA coatings.

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.

Multi-Functional Cardanol Triazine Schiff Base Polyimine Additives for Self-Healing and Super-Hydrophobic Epoxy of Steel Coating

The designing of multifunctional materials in system-level efficiency is one of the main targets and a hot topic for the application of novel green or bio-based materials and structures. In this work, the chemical structure of bio-based cardanol that was derived from cashew oil was modified through a reaction with a bishydrazino-s-triazine derivative followed by condensation polymerization or reaction with terephthaldehyde to obtain a Schiff base polymer. The chemical structures of the modified cardanol-bishydrazino-s-triazine-based monomer and the Schiff base polymer were confirmed from FTIR and NMR spectroscopy analyses. The modified cardanol bishydrazino-s-triazine monomer and polymer were added with different weight ratios during the curing of the epoxy/polyamine hardener to improve the thermal, mechanical, and anti-corrosion characteristics of the epoxy coating of a steel substrate. The data elucidated that the presence of a cardanol bishydrazino-s-triazine monomer and polymer improves the thermal, mechanical, adhesion, and anti-corrosion characteristics of epoxy coatings after exposure for more than 1500 h. The presence of a cardanol- bishydrazino-s-triazine polymer more than 3 wt.% during the curing of epoxy networks produces superhydrophobic and self-healing epoxy coatings. The modification of the epoxy coating with the cardanol bishydrazino-s-triazine polymer improves the seawater contact angle by more than 150° and the adhesion strength of the epoxy coating with the steel surface.

Hybrid Sol-gel Coatings for Corrosion Mitigation: A Critical Review

The corrosion process is a major source of metallic material degradation, particularly in aggressive environments, such as marine ones. Corrosion progression affects the service life of a given metallic structure, which may end in structural failure, leakage, product loss and environmental pollution linked to large financial costs. According to NACE, the annual cost of corrosion worldwide was estimated, in 2016, to be around 3%-4% of the world's gross domestic product. Therefore, the use of methodologies for corrosion mitigation are extremely important. The approaches used can be passive or active. A passive approach is preventive and may be achieved by emplacing a barrier layer, such as a coating that hinders the contact of the metallic substrate with the aggressive environment. An active approach is generally employed when the corrosion is set in. That seeks to reduce the corrosion rate when the protective barrier is already damaged and the aggressive species (i.e., corrosive agents) are in contact with the metallic substrate. In this case, this is more a remediation methodology than a preventive action, such as the use of coatings. The sol-gel synthesis process, over the past few decades, gained remarkable importance in diverse areas of application. Sol-gel allows the combination of inorganic and organic materials in a single-phase and has led to the development of organic-inorganic hybrid (OIH) coatings for several applications, including for corrosion mitigation. This manuscript succinctly reviews the fundamentals of sol-gel concepts and the parameters that influence the processing techniques. The state-of-the-art of the OIH sol-gel coatings reported in the last few years for corrosion protection, are also assessed. Lastly, a brief perspective on the limitations, standing challenges and future perspectives of the field are critically discussed.

Cellulose microfibers (CMFs) as a smart carrier for autonomous self-healing in epoxy coatings

.The cellulose microfibers (CMFs) were synthesized to assist the self-release of loaded product, that provides better corrosion inhibition and self-healing of epoxy coatings.

Self-Repairing Composites for Corrosion Protection: A Review on Recent Strategies and Evaluation Methods

The use of self-healing coatings to protect metal substrates, such as aluminum alloys, stainless steel, carbon steel, and Mg alloys from corrosion is an important aspect for protecting metals and for the economy. During the past decade, extensive transformations on self-healing strategies were introduced in protective coatings, including the use of green components. Scientists used extracts of henna leaves, aloe vera, tobacco, etc. as corrosion inhibitors, and cellulose nanofibers, hallyosite nanotubes, etc. as healing agent containers. This review gives a concise description on the need for self-healing protective coatings for metal parts, the latest extrinsic self-healing strategies, and the techniques used to follow-up the self-healing process to control the corrosion of metal substrates. Common techniques, such as accelerated salt immersion test and electrochemical impedance spectroscopy (EIS), for evaluating the self-healing process in protective coatings are explained. We also show recent advancements procedures, such as scanning vibrating electrode technique (SVET) and scanning electrochemical microscopy (SECM), as successful techniques in evaluating the self-healing process in protective coatings.

Chitosan Nanocomposite Coatings for Food, Paints, and Water Treatment Applications

Worldwide, millions of tons of crustaceans are produced every year and consumed as protein-rich seafood. However, the shells of the crustaceans and other non-edible parts constituting about half of the body mass are usually discarded as waste. These discarded crustacean shells are a prominent source of polysaccharide (chitin) and protein. Chitosan is a de-acetylated form of chitin obtained from the crustacean waste that has attracted attention for applications in food, biomedical, and paint industries due to its characteristic properties, like solubility in weak acids, film-forming ability, pH-sensitivity, biodegradability, and biocompatibility. We present an overview of the application of chitosan in composite coatings for applications in food, paint, and water treatment. In the context of food industries, the main focus is on fabrication and application of chitosan-based composite films and coatings for prolonging the post-harvest life of fruits and vegetables, whereas anti-corrosion and self-healing properties are the main properties considered for antifouling applications in paints in this review.

Electrophoretic Deposition of Chitosan Films Doped with Nd2Ti2O7 Nanoparticles as Protective Coatings against Corrosion in Saline Solutions

In this study, the electrophoretic deposition of chitosan films doped with Nd2Ti2O7 nanoparticles was carried out as corrosion protection systems for exposed materials in aqueous environments rich in chlorides. Completely crystalline Nd2Ti2O7 nanoparticles with an average size of 100-200 nm were obtained. Electrophoretic deposition of chitosan films with Nd2Ti2O7 nanoparticles was possible. With a working voltage of 5 V and 20 minutes of deposition, homogenous chitosan films with a thickness of 4 microns were obtained. According to the FT-IR (Fourier transform infrared spectroscopy), Raman, and XRD (X-ray diffraction) analyses, it was observed that the presence of the nanoparticles modified the properties of the chitosan films, that is, their crystallinity was increased and their moisture absorption capacity was reduced. These modifications caused a better performance against the corrosion of chitosan films deposited on 1018 carbon steel. Its electrochemical evaluation showed that the chitosan films perform as cathodic coatings by affecting the oxygen reduction reaction. This was possible due to the barrier effect of the Nd2Ti2O7 nanoparticles, by blocking the effective area for the diffusion of the aggressive electrolyte species.

Synthesis of new high molecular weight phosphorylated chitosans for improving corrosion protection

Two grades of chitosan [chitosan 30000 g mol−1 (N-chitosan 30) and 250000 g mol−1 (N-chitosan 250)] were functionalized by the Kabachnik–Fields reaction. To obtain the highest phosphonic ester grafting rate (55% and 40% for the N-chitosan 30 and N-chitosan 250, respectively), the pH must be kept constant during the reaction (pH=5). Then, a partial hydrolysis of the ester functions was carried out in HCl medium to generate phosphonic acid functions up to 25% and 20% for the N-chitosan 30 and N-chitosan 250, respectively. It was shown that the grafting of phosphonic acids on chitosan significantly reduced the dynamic viscosity. Afterwards, electrochemical impedance measurements were performed in an aqueous solution (pH=5) in the presence of either N-chitosans or P-chitosans (3 wt.%). The two native N-chitosans were little adsorbed onto the carbon steel surface and the corrosion protection was low. In contrast, the impedance results in the presence of the 30000 g mol−1 phosphorylated chitosan (P-chitosan 30) evidenced the beneficial effect of grafted phosphonic acid on its adsorption on the steel surface. The lower efficiency of the 250000 g mol−1 (P-chitosan 250) was attributed to its high molecular weight which made difficult the interactions between the phosphonic groups and the metallic surface.

Chitosan coatings crosslinked with genipin for corrosion protection of AZ31 magnesium alloy sheets

In this study, coatings of chitosan crosslinked with genipin were prepared on sheets of AZ31 magnesium alloy and their corrosion protection properties were characterized by means of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The coatings were also characterized by means of FTIR and XPS. It was observed that the crosslinking process decreases the corrosion current and shifts the corrosion potential of the alloy to less negative values. The EIS analysis demonstrated that the crosslinking process increases the maximum impedance after short and long exposure times. The superior performance of the crosslinked coatings is related to a lower degree of swelling, as observed in the swelling tests carried out on free-standing films.

Bio-Based Polymers with Potential for Biodegradability

A variety of renewable starting materials, such as sugars and polysaccharides, vegetable oils, lignin, pine resin derivatives, and proteins, have so far been investigated for the preparation of bio-based polymers. Among the various sources of bio-based feedstock, vegetable oils are one of the most widely used starting materials in the polymer industry due to their easy availability, low toxicity, and relative low cost. Another bio-based plastic of great interest is poly(lactic acid) (PLA), widely used in multiple commercial applications nowadays. There is an intrinsic expectation that bio-based polymers are also biodegradable, but in reality there is no guarantee that polymers prepared from biorenewable feedstock exhibit significant or relevant biodegradability. Biodegradability studies are therefore crucial in order to assess the long-term environmental impact of such materials. This review presents a brief overview of the different classes of bio-based polymers, with a strong focus on vegetable oil-derived resins and PLA. An entire section is dedicated to a discussion of the literature addressing the biodegradability of bio-based polymers.

Inhibitor encapsulated, self-healable and cytocompatible chitosan multilayer coating on biodegradable Mg alloy: a pH-responsive design

The design of functional biomaterials that respond intelligently to external stimuli has become a rapidly growing area with widespread interest. This work contributes to the development of a feedback-active anticorrosion system with intriguing self-healing ability to protect magnesium (Mg) from biocorrosion. The system was constituted by an inner micro/nano-porous, ceramic-like pre-coating developed readily from the substrate, and an outermost inhibitor (nanosized cerium (Ce) oxides) containing chitosan (CS) multilayers. Here, the pre-coating acted as both an "anchoring" and a "barrier" layer to acquire structural integrity and improved impedance, respectively. Green CS served as cargo for Ce to be entrapped, harnessing Ce-NH₂ complexation chemistry. The coating barrier properties were evaluated by electrochemical impedance spectroscopy. The active corrosion inhibition was assessed by immersion degradation tests with respect to Mg²⁺ release, pH alteration, crack development, and scanning Kelvin potential. To our delight, the coatings effectively protected the substrate from biocorrosion in vitro compared with bare alloys. Putatively, the pH-triggered formation of Ce oxide precipitation, along with the pH-buffering activity and movable swelling capacity of CS macromolecules, should have contributed to restraining the anodic activity and healing the cracks/defects dynamically. Furthermore, the coated substrate had the biocompatibility to elicit better attachment and growth of osteoblasts.

Structural properties of cerium doped siloxane–PMMA hybrid coatings with high anticorrosive performance

Novel environmentally compliant Ce(iv) doped siloxane–PMMA coatings exhibiting dense cross-linked structure, high thermal stability, unique anticorrosive performance and self-healing ability.

Acid and alkaline dual stimuli-responsive mechanized hollow mesoporous silica nanoparticles as smart nanocontainers for intelligent anticorrosion coatings

The present paper introduces an intelligent anticorrosion coating, based on the mechanized hollow mesoporous silica nanoparticles (HMSs) as smart nanocontainers implanted into the self-assembled nanophase particles (SNAP) coating. As the key component, smart nanocontainers assembled by installing supramolecular nanovalves in the form of the bistable pseudorotaxanes on the external surface of HMSs realize pH-responsive controlled release for corrosion inhibitor, caffeine molecules. The smart nanocontainers encapsulate caffeine molecules at neutral pH, and release the molecules either under acidic or alkaline conditions, which make them spontaneously experience the pH excursions arisen from corrosion process and respond quickly. The intelligent anticorrosion coating was deposited on the surface of aluminum alloy AA2024 and investigated by electrochemical impedance spectroscopy and scanning vibrating electrode technique (SVET). Compared with the pure SNAP coating, the well-dispersed smart nanocontainers not only delay the penetration rate of corrosive species but also repair damaged aluminum oxide layer to maintain the long term anticorrosion behavior. From the experimental results of SVET, the smart nanocontainers with the acid and alkaline dual stimuli-responsive characteristics can simultaneously suppress corrosion activities on microanodic and microcathodic regions, demonstrating an excellent self-healing functionality.

Use of Silica Tubes as Nanocontainers for Corrosion Inhibitor Storage

A new alkyd paint anticorrosion smart coating was developed by using silica nanoparticles as corrosion inhibitor nanocontainers. Silica particles were mixed with the paint at different concentrations to study their performance and ensure their free transportation to the damaged metal. The filling up of silica particles was done preparing three solutions: distilled water, acetone, and a mixture of both, with Fe(NO3)3and silica particles immersed in each of the solutions to adsorb the inhibitor. Acetone solution was the best alternative determined by weight gain analysis made with the inhibitor adsorbed in silica nanocontainers. Steel samples were painted with inhibitor silica nanocontainer coatings and immersed in an aqueous solution of 3% sodium chloride. Polarization curves and electrochemical noise techniques were used to evaluate the corrosion inhibitor system behavior. Good performance was obtained in comparison with samples without inhibitor nanocontainer coating.