Pull-off Adhesion Strength Research Articles

Leveraging colloid and interface science for long-term marine performance of hybrid coatings: Effects of different nanoparticles on anticorrosion and antifouling properties

This study leveraged the unique colloidal and interfacial properties of synthesized SiO2, ZnO, and carbon (CN) nanoparticles as effective nanofillers to enhance the anti-corrosion and antifouling properties of PMMA coatings. By optimizing nanoparticle dispersion, stability, and functional performance within the polymer matrix, we achieved improved surface roughness, hydrophobicity, mechanical stability, and antimicrobial properties. Hybrid coatings containing 1.5 wt% of these nanoparticles were applied to stainless steel (SS) substrates and evaluated through water contact angle measurements, pull-off adhesion strength tests, antibacterial assays, and electrochemical impedance spectroscopy (EIS). The results demonstrate that the synergistic effects of SiO2, ZnO, and CN nanoparticles significantly enhance the coatings' anticorrosion and antifouling characteristics by increasing hydrophobicity, total impedance, and antibacterial activity via reactive oxygen species generated by ZnO and CN. Additionally, over two years, the coating’s long-term protection was assessed by submerging coupons at a 6-meter depth in the Bocana Chica reef barrier, a site with rapid biofouling colonization, making this test a demanding evaluation.

Cytotoxicity and antibacterial susceptibility assessment of a newly developed pectin–chitosan polyelectrolyte composite for dental implants

Biopolymers such as chitosan and pectin are currently attracting significant attention because of their unique properties, which are valuable in the food industry and pharmaceutical applications. These properties include non-toxicity, compatibility with biological systems, natural decomposition ability, and structural adaptability. The objective of this study was to assess the performance of two different ratios of pectin–chitosan polyelectrolyte composite (PCPC) after applying them as a coating to commercially pure titanium (CpTi) substrates using electrospraying. The PCPC was studied in ratios of 1:2 and 1:3, while the control group consisted of CpTi substrates without any coating. The pull-off adhesion strength, cytotoxicity, and antibacterial susceptibility tests were utilized to evaluate the PCPC coatings. In order to determine whether the composite coating was the result of physical blending or chemical bonding, the topographic surface parameters were studied using Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM). PCPC (1:3) had the highest average cell viability of 93.42, 89.88, and 86.85% after 24, 48, and 72 h, respectively, as determined by the cytotoxicity assay, when compared to the other groups. According to the Kirby–Bauer disk diffusion method for testing antibacterial susceptibility, PCPC (1:3) showed the highest average diameter of the zone of inhibition, measuring 14.88, 14.43, and 11.03 mm after 24, 48, and 72 h of incubation, respectively. This difference was highly significant compared to Group 3 at all three time periods. PCPC (1:3) exhibited a significantly higher mean pull-off adhesion strength (521.6 psi) compared to PCPC (1:2), which revealed 419.5 psi. PCPC (1:3) coated substrates exhibited better surface roughness parameters compared to other groups based on the findings of the AFM. The FTIR measurement indicated that both PCPC groups exhibited a purely physical blending in the composite coating. Based on the extent of these successful in vitro experiments, PCPC (1:3) demonstrates its potential as an effective coating layer. Therefore, the findings of this study pave the way for using newly developed PCPC after electrospraying coating on CpTi for dental implants.

Effects of sepiolite addition to acrylic-latex paint on pull-off adhesion strength in nanosilver-impregnated and thermally-modified beech (Fagus orientalis L.) wood

Sepiolite is a silicate mineral that improves the fire properties in solid wood when mixed with a water-based coating. The present study was carried out to investigate and evaluate the effects of sepiolite addition to acrylic-latex paint on the pull-off adhesion strength, as an important characteristic of paints and finishes used in the modern furniture industry and historical furniture as well for preservation and restoration of heritage objects. Sepiolite was added at the rate of 10%, and brushed onto plain-sawn beech (Fagus orientalis L.) wood specimens, unimpregnated and impregnated with a 400 ppm silver nano-suspension, which were further thermally modified at 185 °C for 4 h. The results showed that thermal modification had a decreasing effect on the pull-off adhesion strength, primarily as a result of the thermal degradation of cell-wall polymers (mostly hemicelluloses). Still, a decreased wettability as a result of condensation and plasticization of lignin was also partially influential. Based on the obtained results,thermal modification was found to have a significant influence on pull-off adhesion strength. Sepiolite addition had a decreasing effectin all treatments, though the effect was not statistically significant in all treatments. The maximum and minimum decreases due to sepiolite addition were observed in the unimpregnated control (21%) and the thermally-modified NS-impregnated (4%) specimens. Other aspects of the sepiolite addition, and further studies that cover different types of paints and coatings, should be evaluated before coming to a final firm conclusion in this regard.

Investigating the effect of fundamental properties of materials on the mechanisms of thermal cracking of asphalt mixtures

In most of tests and models to evaluate the thermal cracking of asphalt mixture, the consideration of different elements within the asphalt mixture has been neglected to provide a corrective solution. Accordingly, in this research, the evaluation of the mechanisms of thermal cracking involved assessing the impact of surface free energy (SFE) parameters and other fundamental properties of bitumen and aggregate. These parameters included the adhesion and cohesion free energy, the ratio of the base element to the acid element of the aggregate SFE (RBA), the creep stiffness of bitumen, the rate of changes in creep stiffness (m-value), and specific surface area (SSA) of aggregate. To this end, Wilhelmy plate (WP) test, universal sorption device (USD) test, the bending beam rheometer (BBR) test and the pull-off test were performed. In the following, models were presented to evaluate the effect of mentioned parameters as independent variables on the mechanisms of thermal cracking using an artificial neural network (ANN). The sensitivity analysis of the Artificial Neural Network (ANN) model revealed that in the status of adhesive failure, the cohesion free energy and m-value did not affect the Pull-off adhesion strength. On the other hand, the adhesion free energy, RBA, and the SSA were directly proportional and the creep stiffness was inversely proportional to the Pull-off adhesion strength. Also, in the status of cohesive failure, the adhesion free energy, the RBA, and the SSA did not affect the Pull-off cohesion strength. On the other hand, the cohesion free energy and m-value were directly proportional and the creep stiffness was inversely proportional to the Pull-off cohesion strength.

Bioinspired Microadhesives with Greatly Enhanced Reversible Adhesion Fabricated by Synthesized Silicone Elastomer with Increasing Phenyl Contents.

We present a facile chemical method for fabricating bioinspired microadhesives with significant improved reversible adhesion strength. Four kinds of polysiloxane with gradient varying phenyl contents were synthesized and used to fabricate microadhesives. The chemical structures and mechanical properties, as well as surface properties of the four microadhesives, were confirmed and characterized by ATR-FTIR, DSC, XPS, low-field NMR, tensile tests, and SEM, respectively. The macroadhesion test results revealed that phenyl contents showed remarkable and positive impacts on the macroadhesion performance of microadhesives. The pull-off adhesion strength of microadhesives with 90% phenyl content (0.851 N/cm2) was nearly 300% higher than that of pure PDMS (0.309 N/cm2). The macroadhesion mechanism analysis demonstrates that a larger bulk energy dissipation caused by massive π-π interaction, as well as the hydrophobic interaction and van der Waals forces at the interface synergistically resulted in a significant enhancement of the adhesion performance. Our results demonstrate the remarkable impact of chemical structures on the adhesion of microadhesives, and it is conducive to the further improvement of adhesion properties of bioinspired microadhesives.

Effectiveness of various types of coating materials applied in reinforced concrete exposed to freeze–thaw cycles and chlorides

This study assesses the durability of coated and uncoated concrete surfaces protected with four different coating materials: water-soluble (BW), solvent-based (BR), mineral (MI), and epoxy (EP). The durability assessment includes evaluating the absorption rate of water, pull-off adhesion strength, and coating material thickness. Concrete samples were subjected to immersion in regular water and a 7% urea solution, followed by cyclic freezing and thawing. Furthermore, the diffusion of chloride ions in concrete was evaluated using the impressed voltage method, with the samples exposed to the aging process immersed in a 3.5% NaCl solution. The results indicate that EP and BW coatings were significantly affected by the presence of urea and freeze–thaw cycles, resulting in a 43% and 47% reduction in pull-off adhesion strength, respectively. Notably, the MI-coated concrete samples exposed to urea solution and the freeze–thaw cycles exhibited a significant reduction in the absorption rate due to the accumulation of crystals on the coating surface, resulting in reduced porosity of the material.

Multi-treatments based on polydimethylsiloxane and metal-organic framework wrapped with graphene oxide for achieving long-term corrosion and fouling protection: experimental and density functional theory aspects

In this study, ZIF-8 metal–organic framework decorated on surface of graphene oxide nanosheets and functionalized with silane moieties (F-GO@MOF) is employed to enhance the anti-corrosion, anti-bacterial, and anti-fouling properties of epoxy coatings modified with polydimethylsiloxane (epoxy-PDMS). The epoxy-PDMS/F-GO@MOF sample has revealed super-hydrophobic behavior with least water contact angle changes (Δθ ≈ 5° while Δθ ≈ 17° is recorded for epoxy-PDMS sample) during 20 days of immersion, twice pull-off adhesion strength (6.8 MPa compared to 3.7 MPa for epoxy-PDMS coating), and significantly higher impedance modulus (8.82 × 108 Ω·cm2 which is 3 times more than the epoxy-PDMS sample) during 60 days of immersion in NaCl electrolyte. The anti-bacterial test against Pseudomonas sp. and anti-fouling monitoring in Qingdao port have shown that fewer bacteria and marine organisms are attached on the epoxy-PDMS/F-GO@MOF coating, respectively, indicating advanced fouling and bacterial resistance of the nanocomposite sample. Based on the theoretical studies by density functional theory (DFT) method, the binding of the components in the GO@MOF complex is notably large which could inhibit the penetration of corrosive agents toward the steel substrate. In addition, the stabilization of the GO@MOF nanohybrid is mainly controlled through van der Waals (vdW) forces.

Application and characterization of a novel PVDF-HFP/PVP polymer composite with MoO3 nanowires as a protective coating for wood

The coatings on wood must sometimes give aesthetic and basic protection to wooden elements and prevent the development and transmission of microorganisms. Several polymers containing different nanoparticles have already been offered to day for this purpose. The research presents a novel poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)/polyvinylpyrrolidone (PVP) polymer composite with MoO3 nanowires with the ability to form coating films on wood. The films of the developed coating exhibit elastic behaviour, which depends on the coating film thickness [tested wet film thicknesses (90, 180 and 360) µm]. The coating showed the ability to interact well with the surface of common beech (Fagus sylvatica L.) wood, in terms of wetting (contact angles of 15.6°), fast spilling on the surface, good penetration of the coating in wood structure and formation of up to 40 µm-thick films with excellent pull-off adhesion strength (6 MPa). An increased roughness of wood coated with C + MoO3 was a consequence of wood etching by the dimethylformamide solvent present in the coating. Moreover, the presence of C + MoO3 on wood made it considerably more hydrophobic, with contact angle of water raising to 123° from initially 46° measured on uncoated wood. The irradiation of wood surfaces with ultra-violet light resulted in visible colour changes on both uncoated and coated wood. The wood coated with C + MoO3 has a good resistance to water, alcohol and dry heat (grade 3 to 4). The antimicrobial testing showed that the presence of MoO3 in the coating plays an important role in the resistance of the coated wood to blue-stain fungi and mould development. The developed PVDF-HFP/PVP/MoO3 coating has an excellent ability to interact with the wood surface and has the potential to be used as a protection for wood in sensitive environments.

Bio-based acrylated epoxidized jatropha oil incorporated with graphene nanoplatelets in the assessment of corrosion resistance coating

Vegetable oil has been extensively investigated as a precursor to the eco-friendly coating as an alternative to petrochemical-based resources due to its lower carbon footprint properties. In view of this, jatropha oil (JO), a type of non-edible oil, has received significant attention in this field. The present study was undertaken to utilize acrylated epoxidized jatropha oil (AEJO) resin and to evaluate the anti-corrosion performance with the addition of graphene nanoplatelets (GNP). AEJO-GNP nanocomposites coatings were obtained after three passes of ultraviolet (UV) irradiation. The corrosion protection of all nanocomposites coatings was investigated by electrochemical measurements. The results showed that the corrosion performance of AEJO-GNP nanocomposites coatings improved from the blank coating. Among all coatings tested, AEJO-0.5 wt% GNP exhibited the strongest barrier property and maximum performance in corrosion protection. The result was supported by water contact angle and pull-off adhesion tests. In addition, the highest pull-off adhesion strength for GNP fillers added coatings was established at 0.5 wt% of GNP. High hydrophobicity and pull-off adhesion strength coatings provided a physical barrier that created a tortuosity pathway for corrosive electrolytes to reach the metal surface and thus showed better anti-corrosion resistance. Thus, nanocomposites coatings with 0.5 wt% GNP exhibited the best anti-corrosive efficacy and surface coating property.

Performance evaluation of acrylate terpolymer based coating on anti-carbonation

PurposeThe purpose of this study is to examine how well reinforced concrete structures can be shielded against concrete carbonation using anti-carbonation coatings based on synthetic polymer.Design/methodology/approachApplying free radical polymerization, an acrylate terpolymer emulsion that a surfactant had stabilized was created. A thermogravimetric analysis, minimum film-forming temperature, Fourier transform infrared spectroscopy and particle size distribution are used to characterize the prepared eco-friendly water base acrylate terpolymer emulsion. Using three different percentages of the acrylate terpolymer emulsion produced, 35%, 45% and 55%, the anti-carbonation coating was formed. Tensile strength, tensile strain, elongation, crack-bridging ability, carbon dioxide permeability, chloride ion diffusion, average pull-off adhesion strength, water vapor transmission, gloss, wet scrub resistance, QUV/weathering and storage stability are the characteristics of the anti-carbonation coating.FindingsThe formulated acrylate terpolymer emulsion enhances anti-carbonation coating performance in CO2 permeability, Cl-diffusion, crack bridging, pull-off adhesion strength and water vapor transmission. The formed coating based on the formulated acrylate terpolymer emulsion performed better than its commercial counterpart.Practical implicationsTo protect the steel embedded in concrete from corrosion and increase the life span of concrete, the surface of cement is treated with an anti-carbonation coating based on synthetic acrylate terpolymer emulsion.Social implicationsIn addition to saving lives from building collapse, it maintains the infrastructure for the long run.Originality/valueThe anti-carbonation coating, which is based on the synthetic acrylate terpolymer emulsion, is environmentally benign and stops the entry of carbon dioxide and chlorides, which are the main causes of steel corrosion in concrete.

Evaluation of the self-healing capabilities and resistance to thermal cycling of a shape-memory epoxy coating containing polycaprolactone microspheres

The aim of this work was to prepare a shape-memory epoxy coating containing polycaprolactone microspheres (SMEP-PCL) and study its resistance to thermal cycling, which is yet to be evaluated in coatings prepared with similar approaches, as well as further characterize its self-healing capabilities. Firstly, the prepared microspheres were characterized by scanning electron microscopy (SEM) and laser diffraction. Afterwards, the dispersion of the PCL microspheres in the coating was examined and experiments were conducted with differential scanning calorimetry (DSC) and Fourier-transform infrared spectroscopy (FTIR) to determine the glass transition temperature and investigate the curing reaction of the prepared coating, respectively. Then, the healing promoted by the reversible plasticity and the melt of the polycaprolactone microspheres mechanisms were studied by SEM, Raman Imaging, electrochemical impedance spectroscopy (EIS) and scanning vibrating electrode technique (SVET). Finally, thermal cycling tests were conducted and the samples were later visually evaluated for thermal stress damage and by EIS and pull-off adhesion strength tests. The SMEP-PCL of the present work was able to reproduce the self-healing results obtained from previous reports, even improving upon the self-healing efficiency obtained in other studies, in the SVET experiment. The results of the EIS measurements after the thermal cycles, pointed out to a minor reduction on the barrier properties of the SMEP and SMEP-PCL, which should be further investigated. Nonetheless, the adherence of both coatings was unhindered by the thermal cycles, which is a highly positive result for the future application of coatings based on this approach. Also, the SMEP-PCL exhibited substantially higher average values of adhesion strength compared to the SMEP, showing that the addition of PCL microspheres significantly improved the adherence of the coating and signaling great compatibility between them. This work also underlines how the healing efficiency of coatings with this approach are highly dependent on the type and extension of damage, as the healing observed in the two types of damage studied were exceedingly different.

Experimental Test of Reinforced Timber of FRCM-PBO with Pull-Off Adhesion Method.

The article describes the results of pull-off adhesion strength of the FRCM-PBO (Fiber Reinforced Cementitious Matrix-p-Phenylene benzobis oxazole) composite adhered to the epoxy resin layer which is the connector with the timber beam. In addition, this paper shows the results of the tests of resistance to pull-off the epoxy resin layer from the pine beam. The tests were carried out based on the Polish Standard PN-EN 1542. The Pearson linear correlation analysis was also carried out in order to determine the correlation between the obtained results and the destructive forces. The factors that occurred during the test that may affect its results, such as the method of applying the bursting force, surface preparation of the tested elements and the types of substrate destruction, were also characterized. The experimental data show that in all the tested samples, non-initial adhesive destruction between the adhesive layer and the disc was observed.

Hot-Melt and Pressure-Sensitive Adhesives Based on Styrene-Isoprene-Styrene Triblock Copolymer, Asphaltene/Resin Blend and Naphthenic Oil.

Asphaltene/resin blend (ARB) extracted from heavy crude oil was used to modify poly(styrene-block-isoprene-block-styrene) (SIS) to make it an adhesive. There were prepared double and triple mixtures containing 10–60% SIS, 10–40% ARB, and 10–50% naphthenic oil used as an additional plasticizer. The viscoelasticity of the mixtures at 25 °C and 120 °C was studied, their flow curves were obtained, and the temperature dependences of the loss tangent and the components of the complex modulus were measured. In addition, the mixtures were used as hot-melt adhesives (HMAs) and pressure-sensitive adhesives (PSAs) in the shear, peel, and pull-off tests of the adhesive bonds that they formed with steel. Both naphthenic oil and ARB act as plasticizers for SIS and make it sticky. However, only the combined use of ARB and the oil allows for achieving the best set of adhesive properties of the SIS-based mixture. High-quality HMA requires low oil content (optimal SIS/ARB/oil ratio is 50/40/10, pull-off adhesion strength (τt) of 1990 kPa), whereas a lot of the oil is needed to give SIS characteristics of a PSA (SIS/ARB/oil is 20/40/40, τt of 100 kPa). At the same time, the resulting PSA can be used as a hot-melt pressure-sensitive adhesive (HMPSA) that has many times lower viscosity than HMA (13.9 Pa·s versus 2640 Pa·s at 120 °C and 1 s−1) but provides a less strong adhesive bond (τt of 960 kPa).

Mechanical and physical assessment of epoxy, mineral, solvent-based, and water-soluble coating materials

This paper assesses the behavior of mineral, epoxy (EP), solvent, and water-soluble coatings when exposed to salt and regular water for 28 days. Also, it evaluates the pull-off adhesion strength of the same coating materials applied to concrete slabs saturated with oil and water and dried with two different processes: air-dried for 28 days and air-dried for 14 days plus 14 days in the oven at 70 °C. Properties such as carbonation, water absorption rate, pull-off adhesion strength were evaluated for all coatings, and tensile strength, Young’s modulus, and elongation percentage were calculated for mineral coatings. According to the results, the EP coating showed the best performance with the highest pull-off adhesion strength (2.55 MPa) and lowest absorption rate, about 0.02 ± 0.002 g/m2 day in saltwater and 0.03 ± 0.002 g/m2 day in regular water. In addition, EP coatings also presented the lowest carbonation rate and the highest suppress ratio. The excellent performance of epoxy coatings is mainly due to their low porosity and the ability to decrease chloride diffusion, making them better than other types of coatings investigated in this study.

Novel Micronized Mica Modified Casein–Aluminum Hydroxide as Fire Retardant Coatings for Wood Products

Sustainable coating solutions that function as a fire retardant for wood are still a challenging topic for the academic and industrial sectors. In this study, composite coatings of casein protein mixed with mica and aluminum trihydroxide (ATH) were tested as fire retardants for wood and plywood; coating degradation and fire retardancy performance were assessed with a cone calorimeter, and a thermogravimeter was used for the thermal stability measurement. The results indicated that casein–mica composites were beneficial as coatings. The heat release rate (HRR) and the total heat released (THR) of the sample coated with casein–mica composite were reduced by 55% and 37%, respectively; the time to ignition was increased by 27% compared to the untreated sample. However, the TTI of the sample coated with the casein–mica–ATH composite was increased by 156%; the PHR and THR were reduced by 31% and 28%, respectively. This is attributed to the yielded insulating surface layer, active catalytic sites, and the crosslink from mica and endothermic decomposition of ATH and casein producing different fragments which create multiple modes of action, leading to significant roles in suppressing fire spread. The multiple modes of action involved in the prepared composites are presented in detail. Coating wear resistance was investigated using a Taber Abrader, and adhesion interaction between wood and a coated composite were investigated by applying a pull-off test. While the addition of the three filler types to casein caused a decrease in the pull-off adhesion strength by up to 38%, their abrasion resistance was greatly increased by as much as 80%.

UV protective bio-based epoxy/carbon quantum dots nanocomposite coatings: Synthesis and investigation of properties

This research focuses on synthesis and study of the properties of castor oil-based epoxy/carbon quantum dots (COEp/CQDs) nanocomposite coatings possessing resistance against UV. First, CQDs were synthesized by pyrolysis of starch using microwave-assisted method and characterized via various spectroscopic and microscopic methods. Next, certain quantity of castor oil as a renewable resource, CQDs with different weight percentages and a curing agent were added to epoxy resin and consequently COEp/CQDs were prepared. Through findings of FTIR, photoluminescence and UV-visible spectroscopy analyses, existent functional groups and fluorescent feature of the nanocomposite coatings were confirmed. UV-vis spectroscopy approved UV resistance of the COEp/CQDs coatings. As concentration of CQDs increased in resin matrix, UV absorption was maximized. The morphology and uniform dispersion of CQDs in the coatings matrix were verified by FESEM analysis. Results of TGA, pull-off adhesion strength and tensile tests, and DMTA analysis proved adding CQDs to the resin matrix led to progress of thermal endurance, adhesion strength, mechanical and viscoelastic properties of the synthesized coatings including an increase in storage modulus and Tg.

Enhanced mechanical performances of epoxy asphalt adhesives modified by graphene oxide

The graphene oxide (GO) was used to improve the mechanical performances of epoxy asphalt (EA) by preparing GO/EA composite. The influence of the GO dosage on the micro-structure, curing rheology, mechanical and thermal properties of GO/EA was investigated. According to the XRD and Fourier transform infrared spectra, the GO was exfoliated in the EA matrix and modified EA by non-covalent strategy. GO decreased the rotational viscosity of EA and increased the pot life. The GO/EA with 0.1 wt.% GO showed excellent toughness that the elongation at break was increased by 164%, and the tensile and pull-off adhesion strength were nearly equal to that of EA. The addition of GO improved the original thermal decomposition temperature (T 5%), glass transition temperature (T g), compatibility and stiffness of the EA. The improved mechanical and thermal properties of GO/EA may be attributed to (1) excellent performances of GO and (2) inhibiting effect of GO on the EA curing process.

Distinctive roles of graphene oxide, ZnO quantum dots, and their nanohybrids in anti-corrosion and anti-fouling performance of waterborne epoxy coatings

In this research, the amino-silane functionalized ZnO quantum dots (F-ZnO QDs), graphene oxide (F-GO), and their nanohybrids (F-GO@ZnO QDs) are used as effective nanofillers to improve the anti-corrosion and anti-fouling properties of waterborne epoxy coatings. The synthesized nanomaterials before and after silane functionalization are characterized by X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. Then, the nanocomposite waterborne epoxy coatings loaded with 0.1 wt% F-ZnO QDs, F-GO, and F-GO@ZnO QDs are prepared through solution mixing method. The effects of different nanofillers on the surface roughness, water contact angle, pull-off adhesion strength, fracture surface, and corrosion resistance of the nanocomposite coatings are considered. The results reveal that the uniformly dispersed F-GO@ZnO QDs in the fracture surface of the coating could provide the highest barrier and corrosion resistance on the steel substrates. Meanwhile, the nanocomposite coatings have higher water contact angle and higher adhesion strength to the substrates. The anti-bacterial and anti-fouling properties of the nanocomposite coatings have also been confirmed. The multifunctional performance of the epoxy/F-GO@ZnO QDs is assigned to the synergy effect between the GO, ZnO QDs, and amino-silane; exhibiting the importance of the nanohybrids to combine the advantages of different nanomaterials in one coating system.

Ultrastable Porous Covalent Organic Framework Assembled Carbon Nanotube as a Novel Nanocontainer for Anti-Corrosion Coatings: Experimental and Computational Studies.

Covalent organic frameworks (COFs) have been proposed as a wholly organic architecture sharing high crystallinity, porosity, and tuneability. Moreover, they exhibit highly stable structures against harsh chemical environments, including boiling water, strong acids and bases, and oxidation and reduction conditions, making them good candidates for extreme conditions. For the first time, a porous COF structure based on terephthalaldehyde and melamine was synthesized and employed as a novel nanocontainer for hosting corrosion inhibitors to provide a coating with superior active/passive anti-corrosion properties. In this study, the multi-walled carbon nanotube was utilized as a platform for growing COF (CC) to improve the coating's barrier and thermo-mechanical properties. The zinc cations were loaded into the CC structure (called CCZ) as one of the most promising inhibitors for mild steel. The COF-based nanoparticles' characterization was done by Fourier transform infrared, Raman, X-ray diffraction, thermogravimetric analysis, Brunauer-Emmett-Teller, field emission scanning electron microscopy, and transmission electron microscopy (TEM) techniques. Moreover, the Density functional theory modeling and molecular dynamics simulation quantitatively highlighted the adsorption propensity of the investigated COF structures onto the oxidized CNT-based nanostructures and the interactions of epoxy with these nanostructures. The CCZ nanoparticles (NPs) showed 75% inhibition efficiency in saline solution and 418 ppm zinc ions release after 24 h at acidic pH. The CCZ/EP coating revealed the smart release of inhibitor for 24 h and represented excellent barrier properties after 9 weeks of immersion in saline solution. In terms of mechanical properties, the elastic modulus values derived from the dynamic mechanical thermal analyzer were enhanced by 107 and 137% in CC/EP and CCZ/EP samples compared to the neat epoxy. Furthermore, the yield stress and breakpoint elongation were strengthened by 102 and 63% for the CC/EP sample, respectively. Finally, the highest pull-off adhesion strength in dry (8.53 MPa) and wet (2.7 MPa) conditions, along with the lowest adhesion loss (68.3%), was related to the CCZ/EP sample.

Autonomous-healing and smart anti-corrosion mechanism of polyurethane embedded with a novel synthesized microcapsule containing sodium dodecyl sulfate as a corrosion inhibitor.

The self-healing and smart anti-corrosion behavior of a polyurethane coating enhanced with micro-sized capsules have been investigated. An in situ polymerization technique was employed to synthesize a novel microcapsule containing sodium dodecyl sulfate (SDS) as a corrosion inhibitor in linseed oil (LO). FE-SEM, FT-IR and TG analysis were used to characterize the prepared microcapsules. The capsules were separately embedded in polyurethane at 1, 4 and 7 wt% and the coating properties were investigated through the water absorption rate and pull-off adhesion strength. The scratched coating was then subjected to 3.5 wt% NaCl solution to investigate the self-healing ability. Electrochemical measurements were carried out by means OCP, EIS and potentiodynamic polarization and the inhibition mechanism of SDS was discussed in terms of interfacial interactions. Despite the adhesion strength, a positive effect was observed for the water uptake, after addition of the microcapsules. 4 wt% of LO/SDS microcapsules showed the best results as its inhibition efficiency was more than 90% compared to single linseed oil capsules. EDS mapping was also employed to verify the successful release and distribution of the SDS, when subjected to scratching.