Elimination of oxygen inhibition is still a challenge in the preparation of copolymers for steel bridge deck coatings industry by redox free radical polymerization (RFRP) technique in air and at room temperature. Herein, solvent-free paraffin wax composite alicyclic polyurethane acrylate (PW/APUA) coatings cured in air and at room temperature were developed by RFRP technique, and the efficacy and mechanism of oxygen inhibition elimination by paraffin wax during curing was investigated. The results of tensile, contact angle (CA) and water absorption (WA) tests showed that compared with pure APUA coating, the PW/APUA coatings exhibited superior mechanical properties and water resistance at room temperature, with tensile strength, elongation at break and CA up to 25.1 MPa, 204.23 % and 112.5°, respectively, and WA down to 0.008 %. Thermogravimetric analysis (TGA) suggested that the thermal initial decomposition of the coating increased from 180 °C to 200 °C after incorporation of paraffin wax. Differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) indicated that two glass transition temperatures of PW/APUA coating with 0.3 % paraffin wax were −88.4 °C and 92.6 °C, respectively. Moreover, microstructural characterization of PW/APUA coatings revealed that paraffin wax eliminated oxygen inhibition by forming a dense barrier layer on the air contact surface of the APUA coating. Furthermore, the paraffin wax molecules co-crystallized with the non-polar groups of acrylates, but did not form new chemical bonds. This study provides a distinct and general strategy for eliminating oxygen inhibition of RFRP technology in air.

Bioelectric signals are an important factor that maintain cell functions and affect cell behavior. Conductive polymers (CPs) can facilitate cell activity and reinforce the signal transmission among cells, so CPs have triggered attention to the tissue regeneration. In this study, layer-by-layer strategy is employed and polyvinyl alcohol (PVA)/polylactic acid (PLA) braids are polymerized in polypyrrole (PPy) by ice template method. The stents that are deposited with PPy are then immersed in dopamine solution, which during polydopamine (PDA) is coated over the stents naturally. Finally, PDA is used as a template to form hydroxyapatite (HA) coating layer with the aim of electrochemical deposition. The test results indicate that PPy forms an even conductive network over the surface of braids while the electrochemically deposited HA made with PDA is adsorbed over the scaffolds in a needle pattern. According to the cyclic voltammetry measurement, the CV curves of HA/PDA/PPy scaffolds basically retain specified and thus the scaffolds possess stabilized electrochemical activity. At last, HA/PDA/PPy scaffolds are immersed in a simulated body fluid (SBF) for ten days and the surface is completely wrapped in HA, indicating an excellent biomineralization capability. MTT assay results suggest that the cell viability of composite scaffolds is improved by 188 %. This study provides a new perspective, a layer-by-layer structured bone scaffolds, broadening the application range of textile structure in the bone tissue engineering field.

A zinc-based metal-organic framework (MOF) was synthesized by co-precipitation/hydrothermal approaches using four zinc precursors, zinc nitrate hexahedral, zinc gluconate, zinc acetate dihedral, and zinc chloride. The anti-corrosion performance of the mild steel substrate was evaluated by its stability and specific surface area (SSA). All characterization confirmed the successful synthesis of MOF particles. Because of the large SSA (2164 m2.g−1) and mild dissolution rate, according to BET and ICP-OES results, respectively, the zinc acetate salt was determined to be the ideal precursor. Additionally, this MOF considerably improved the anti-corrosion capability of the ZIF-8-A/epoxy coating (EC) on the substrate, and after 24 h of subjection to the saline solution, the total impedance value at 0.01 Hz for the scratched ZIF-8-A/EC (106,638 Ω.cm2) reached 3.92 times and more than 1.86 times higher than the impedance magnitudes of the neat EC and other ZIF-8/ECs samples, respectively. Furthermore, the ZIF-8-A indicated superior barrier anti-corrosion (|Z|f=0.01 more than 1010 Ω.cm2) feature during seven weeks of immersion. In the presence of ZIF-8-A, the pull-off tests indicated the best adhesion strength (2.61 MPa) among other coatings in wet conditions. Additionally, dynamic mechanical thermal analysis (DMTA), and tensile tests showed robust corrosion prevention and excellent thermo/mechanical performance of the ZIF-8/EC sample.

Graphene-based materials have great application potential in Mg alloy surface protection, while traditional graphene-based waterborne coating has poor water-resistance stability. In this work, a reduced graphene oxide (RGO)/polyvinyl alcohol (PVA)/glutaraldehyde (GA) coating (RPG) with a “brick-and-mortar” structure was prepared on the surface of Mg alloys to achieve integrated protection against corrosion and wear. The synergistic effect of covalent bonding fixation and thermal reduction coupling enhanced the hydrophobicity and interface bonding of waterborne graphene-based coatings, thus improving the barrier effect and corrosion resistance of samples. Significantly, the incorporation of GA in the bionic structure improved the thermal stability and gap-filling effect of the coating through its covalent bonding fixation effect on RGO sheets, which decreased the micro-gaps and defects between layers caused by thermal expansion during in-situ thermal reduction. Furthermore, RPG coating has enhanced anti-wear ability after 170 °C heat treatment. The thermal removal of oxygen-containing functional groups contributed to improving surface lubricity, although the covalent bonding fixation effect constrained the low shear relative slip between RGO sheets. This study would provide guidance for the bionic construction of waterborne graphene-based coatings with integrated corrosion and wear resistance.

With the ecological crisis and serious problems of marine biofouling, the bionic antifouling strategy of natural organisms is explored for the construction of antifouling coating and replacement of the traditional toxic antifouling coating. In this work, inspired by Laminaria japonica's ability to inhibit marine fouling by the combination with physical micromorphology, chemical composition and bioactive substances, a novel PDMS-based antifouling coating with multiple synergistic antifouling properties is fabricated by layer by layer (LbL) self-assembly method. Firstly, the natural active substance (capsaicin) is introduced into the nanocapsule by the microemulsion method (CAP@CS). Subsequently, the nanocapsules are stably deposited on PDMS surface modified by the guanidine-hexamethylenediamine-PEI / sodium alginate (GHPEI/ALG)*n films through LbL assembly method to prepare the (GHPEI/ALG-CAP@CS-x)*n films with multiple antifouling properties. Our study indicates that this biomimetic surface has excellent antifouling ability against bacteria (99.2 ± 0.6 %) and diatoms (0.08 ± 0.05 %), which proves the great potential applications of this synergistic antifouling strategy demonstrated in marine engineering in the future.

Organic coatings are susceptible to damage in the form of cracking, leading to the decline and ultimate failure of functionality, and incurring enormous repair costs. Self-healing coatings are coatings which can heal damage spontaneously, without external diagnosis or intervention, and promise high performance and outstanding durability. This review summarizes and evaluates the current state of self-healing organic coatings, from foundational studies to the most recent, highly optimized designs. Focus is given to the underlying chemistry of self-healing, the diverse set of self-healing strategies, their relative strengths and weaknesses, and the feasibility of self-healing organic coatings in wider commercial applications.

In this study, we synthesized five novel flavonol camphorsulfonates (HFSs) photoinitiators using a flavonol scaffold as the chromophore. These HFSs demonstrated photoinitiating properties in both one-component (Norrish Type I) and two-component photoinitiating systems, with high final reaction function conversion and excellent polymerization rates of acrylates in free radical photopolymerization. Additionally, HFSs exhibited thermal stability in thermogravimetric tests. To explain the photoinitiating mechanisms, we used various complementary approaches, including real-time FT-IR spectroscopy, UV–Vis absorption spectroscopy, fluorescence spectroscopy, analysis of photolysis products, cyclic voltammetry, free radical capture experiments and molecular modelling calculations.

Series of Waterborne Polyurethanes (WPUs) were synthesized by molecular structure design, using sodium 2-((2-aminoethyl) amino) ethanesulfonate (AAS) as the post-chain extender, and selecting poly-1,4-butanediol adipate (PBA) and isophorone diisocyanate (IPDI) as the soft segment and hard segment, respectively. The effects of changes in PBA molecular weight and AAS content on the properties of WPUs were investigated through analysis of adhesion, mechanical properties, and thermal properties. The result showed that the T-peel strength, shear strength, and adhesion of the film reached 7.75 ± 0.48 N/mm, 1.81 ± 0.08 MPa, and 1.45 ± 0.11 MPa, respectively, due to the higher hydrogen bond density in the molecular structure when the Mn of PBA was 2000 g/mol. Based on the selection, the introduction of sulfamate increased the urea bond content of the system, further increasing the intramolecular hydrogen bond density. When the content of AAS was 1.0 wt%, the T-peel strength, shear strength, and adhesion of the film were increased to the highest values of 10.63 ± 0.30 N/mm, 2.08 ± 0.09 MPa, and 2.41 ± 0.08 MPa, respectively. Therefore, WPU has a wide range of applications in the field of water-based ink binders due to its high adhesive strength.

Recently, polymer coatings containing metal-organic frameworks (MOFs) have offered promising potential as anti-corrosion coatings. In this regard, the current study investigated two types of synthesized MOFs composed of Cu and Ni ions coordinated with 2-methylimidazole, as novel nanofillers with high anti-corrosion behavior. Molecular structures of synthesized MOFs were optimized by Gaussian software. FTIR, Raman spectroscopy, XRD, and EDX analysis of nanoparticles indicated that metal ions have successfully reacted and coordinated with the organic ligands. FE-SEM and TEM images of nanoparticles showed planar and spherical structures for Cu-MOF and Ni-MOF, respectively. The BET test illustrated the porous structure of synthesized nanoparticles with a high surface area and 35 nm average pore diameters. Moreover, UV–Vis analysis revealed Cu-MOF and Ni-MOF pH-responsive behavior. These nanostructured materials were incorporated into an epoxy (EP) matrix to be applied to mild steel substrates. Electrochemical impedance spectroscopy (EIS) and salt spray examination demonstrated active corrosion inhibition and self-healing behavior of nanocomposite coatings. The salt spray test indicated improved performance with fewer corrosion products and reduced blistering and delamination. Coatings without an artificial scratch that contained 0.15 wt% MOF nanoparticles exhibited long-term anti-corrosion performance, even after being immersed in saline solution for nine weeks; in terms of |Z|0.01Hz, Ni-MOF/EP and Cu-MOF/EP (109 Ω·cm2) outperformed neat EP (105 Ω·cm2).

Polymer insulation materials are subjected to a combination of electromagnetic fields, mechanical stresses, long-term light exposure, ambient temperature and other operating conditions that produce mechanical and electrical tree damage which lead to insulation failure. Self-healing technology is a fundamental solution to this problem. However, effective long-term self-healing of mechanical and electrical tree damage to insulating materials is extremely challenging. To address this issue, this work reports a magnetic field dual responsive blueberry-like microsphere (MFDR-BLMS) that makes a breakthrough in the long-term self-healing of mechanical and electrical damage. The microspheres are attracted to the vulnerable area of the insulating material by the directional magnetic field. When the damage come into contact with the microspheres, the high thermal conductivity microspheres as a whole rapidly melt and fill the damage channels under the action of electromagnetic induction heating. This method achieves a magnetically dual-action, non-contact, long-term effective self-healing of mechanical and electrical tree damage after photothermal aging of insulation materials. This is expected to eliminate the requirement for human contact during the repair process under live conditions and provides a new technological idea for the industrial application of self-healing materials for electrical insulation.

The wide application of epoxy resin (EP) causes a great potential fire risk to humans and the environment. To effectively reduce the fire risk of EP, we designed a novel P, N-doped organic-inorganic hierarchical core-shell nanostructure (BN@PEI@UiO-66@PPA). Encouragingly, with only 2 wt% of BN@PEI@UiO-66@PPA, the peak heat release rate (PHRR) and total heat release (THR) were reduced by 47.2 % and 47.9 %, respectively, compared with those of pure EP, indicating a considerable enhancement in flame retardancy. The peak smoke release rate (PSPR), total smoke production (TSP), peak CO production rate (PCOPR), and peak CO2 production rate (PCO2PR) were significantly reduced by 46.0 %, 52.7 %, 72.1 %, and 75.1 %, respectively, compared with those of pure EP, indicating a significant reduction in fire toxicity. In addition, the mass of the char residue of BN@PEI@UiO-66@PPA/EP increased by 185.3 %, and the graphitization degree and thermal stability of the char were significantly improved. The results indicate that the various components in BN@PEI@UiO-66@PPA were functionally different and cross-assisted to form dense P-N-C char with high graphitization and high thermal stability, which effectively improved the fire safety of EP. This work provides a new reference for the construction of multi-component hierarchical structures to optimize their application in the field of fire safety of polymer composites.

Passivation is an essential process in the research and application of reactive and air-sensitive materials, and there has been an increasing demand to develop materials for stable but readily removable temporary passivation layers. Paraffin coating has been suggested as a possible candidate for such applications, which, however, further requires the demonstration of thin paraffin coating with complete surface coverage as well as effective depassivation performance. In this study, we demonstrate on-demand removable passivation using nanoscale paraffin layers fabricated using a spin-coating technique. Based on the Emslie Bonner and Peck's and Mark-Houwink-Sakurada (MHS) equations, eicosane and hexane were selected as the solute and solvent, respectively, to ensure low viscosity for the fabrication of nanoscale paraffin layers, facilitating depassivation process under a vacuum. Optimizing the solution concentration and spin speed generates nanoscale paraffin layers with complete surface coverage, which is confirmed through optical microscopic images and subsequent image processing using Python. The simple removal of the nanoscale paraffin layer through vacuum treatment allows us to revisit a passivated surface underneath, and subsequent contact resistance and x-ray photoelectron spectroscopy measurements evince the suppressed surface oxidation of paraffin-coated silicon samples. These results further attest to the applicability of paraffin coating as an on-demand removable passivation technique.

The purpose of this article is to investigate the stability of multilayered coatings composed of chitosan, poly(sodium 4-styrene sulfonate) and poly(acrylic acid) against various salt solutions using Quartz Crystal Microbalance-Dissipation (QCM-D) and analyze the effects of salt concentration, upper layer charge type and multilayer structure. The study also examines the impact of methanol and heptane on the swelling behavior of the multilayers. The results show that chitosan-poly(acrylic acid)-based coatings remained mostly stable against salt solutions and solvents, except for 1 M sodium hypochlorite, while 5 bilayered chitosan-poly(sodium 4-styrene sulfonate) completely decomposed to initial polyelectrolytes against 1 M magnesium chloride and sodium hypochlorite. The multilayer stabilities of coatings do not change depending on the surface charge type while some changes occur in adsorbed and desorbed amounts during the salt passage and rinsing steps. Chitosan-based coatings exhibit a greater mass loss percentage and change in dissipation against 1 M magnesium chloride than sodium chloride-treated multilayers because of the high ionic strength of magnesium chloride solution. The multilayered coatings with poly(acrylic acid) showed larger changes in dissipation values and reversibility in swelling. This behavior can be useful for shape memory coatings and drug delivery platforms of Layer-by-Layer assembled multilayers.

Polyethylene terephthalate (PET) fabric is commonly used in people's daily life due to its excellent performance. However, PET is flammable and easy to produce dripping resulting in a potential fire hazard. It is of great significance to endow PET fabric with flame retardancy and anti-dripping simultaneously. Bio-based compounds have received more and more attention in flame retardant field for their eco-friendly, renewable and sustainable advantages. However, their poor durability restricts the industrial application. In this study, 3-glycidyloxypropyltrimethoxysilane (GPTMS) was used as the organic crosslinking agent, which was covalently binded with phytic acid (PA) and chitosan (CS) to endow PET fabrics with durable flame retardancy. The treated PET fabric with 20 bi-layers (BLs) CS/PA coating using layer-by-layer assembly method obtained a LOI value of 34 % and damage length of 6.5 cm, demonstrating that the excellent flame retardancy of treated PET fabric. After 4 times washing, its LOI value was higher than 26 %, indicating the good flame retardant durability of treated PET fabrics. This research provides a basis for durable flame retardant textile using bio-based flame retardants by forming covalent bonds through the crosslinking agent containing reactive epoxy groups.

New amphiphilic cationic copolymers based on poly((methacryloyloxy) ethyl trimethylammonium chloride) (PMETAC) and bio-based poly(thymol methacrylate) (PTMA) were prepared by atom transfer radical polymerization (ATRP) methods, using low concentration of metal catalyst and a bio-based eutectic mixture (EM), composed of L-menthol and thymol. The antimicrobial activity of the polymers was evaluated against Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) bacteria.The results in solution showed that increasing the terpenic segment (PTMA) in the copolymers resulted in lower antimicrobial activity against S. aureus (as the MIC increases from 3.1 to 100 μM) and higher activity against E. coli (as the MIC decreases from 400 to 200 μM).Scanning electron microscopy (SEM) analysis suggests that polymers affected the bacterial viability by damaging the cell structure. The synthesized biocidal polymers were used as additives in polyurethane-based varnish formulations to produce bioactive coated surfaces that were found to be more active against E. coli. Coatings containing either PTMA or PMETAC homopolymers were more efficient than those containing PMETAC-co-PTMA copolymers. A dramatic improvement in the antimicrobial activity of PMETAC-containing varnish against both S. aureus (3 orders of magnitude) and E. coli (4 orders of magnitude) was observed when an aqueous solution of the homopolymer was applied to the dried varnish instead of being incorporated into the varnish formulation. The strategy presented here is simple and opens the door for the preparation of customized bioactive surfaces to prevent bacterial infections.

Despite the significant progress in high thermal-resisting photocurable resin, the simultaneous achievement of robustness, stretchability, and dielectric properties in modified naphthalene-type photocurable resin remains a great challenge owing to intrinsic restrictions mediated by strong π-π stacking effect. Herein, a simple and feasible method is demonstrated to respectively introduce three selected di-functional acid chain extenders into 1,6-naphthalene diglycidyl ether (NDE), and prepare a series of naphthalene-type photocurable enhancement resin with excellent thermal/mechanical properties and low dielectric traits. Most importantly, the effect of the increase of succinic acid (SA) chain-extending segments on the thermal and mechanical properties of SA chain-extending NDE (S-NDE) resin is systematically investigated. An optimized synthesized route is presented by chain extension chemical strategy, which enables the improvement of the “seesaw” issue between high heat resistance and mechanical robustness. As a consequence, the optimized UV-curing S-NDE thin film exhibits robust tensile strength (75.45 ± 4.46 MPa), excellent heat resistance (Tg: 145.4 °C), high stretchability (7.22 ± 0.85 %), and desired dielectric constant (2.2). Meanwhile, the uncured S-NDE resin exhibited an excellent alkali elution property within 5 min. An actually printed circuit board (PCB) solder resistance coating/patterning application is further demonstrated based on the selective elution property of high-performance formulated S-NDE green ink, providing an efficient strategy for the design and fabrication of high-performance naphthalene-type photocurable materials.

Although poly(vinyl chloride) (PVC) is produced on a large scale industrially by emulsion and suspension polymerization, it is usually processed from the dry state and is seldom directly used as an aqueous polymer dispersion. In this work we demonstrate that by control of particle morphology and particle size distribution it is possible to produce latexes with high PVC content from which polymer films can be cast directly. A series of hybrid PVC/acrylic latexes with a core-shell structure are produced by semi-batch emulsion polymerization using a preformed PVC latex as a seed. Although monomodal particles of this type have a minimum film formation temperature in excess of 80 °C when the content of PVC is high, it is shown that through the use of a bimodal particle size distribution the packing efficiency of the spherical PVC domains is increased such that room temperature film formation is possible with PVC content up to 80 wt%.

In this paper, a novel ethanol-water Tris buffer system was developed to construct a polydopamine (PDA) protective layer on the surface of polytetrafluoro-wax (PFW) to obtain PFW@PDA with excellent hydrophilicity. The wood-based slurry was obtained by solvent encapsulation and lignin-cellulose assisted ball milling process using waste poplar powder and flake graphite as raw materials. PFW@PDA exhibited excellent dispersion stability in such aqueous slurry and the water was removed from the slurry by vacuum filtration to obtain paper-based composite films. Based on the self-reinforcement of the lignin-cellulose cross-linked network, construction of graphene thermal conductivity network, and the effectiveness of PFW@PDA for wear reduction and self-lubricating. This composite film exhibits excellent water resistance, good thermal stability, and superior mechanical properties. The friction coefficient and wear rate were reduced by 71.3 % and 166.7 %, respectively, compared with the unmodified material. Besides, the end-of-life products can be recycled by mechanical crushing in water, which exhibits a good balance between wear resistance and sustainability, providing a new idea for improving the hydrophilicity of fluorinated polymers and enhancing paper-based friction materials.

Developing a strategy to improve the flame retardancy and water resistance of waterborne bio-based coatings on wood is an effective route to enhance safety and applicability of timbers. In this work, the waterborne itaconate-based unsaturated polyester (IAF) were synthesized from biomass-derived itaconic acid (IA) and flame retardants FRC-6 by melt polycondensation in one pot, which was investigated as an ideal waterborne resin for UV-curable coating applications. A series of UV-cured hybrid coatings on wood were prepared consisting of IAF, N-(Hydroxymethyl) acrylamide (NMA), and γ-methacryloxypropyltrimethoxysilane (MPS) in various proportions via UV-curing and sol-gel process. The incorporation of MPS enhanced the rigidity, cross-linkage, and water resistance of UV-cured hybrid coatings, but the excessive silicone gel limited the further improvement of coating performances due to the phase separation and reduced film-forming property. Moreover, the UV-cured hybrid coatings appeared exceptional charring properties and endowed wood with superior flame retardancy. It was noticed that P/N/Si synergistically promoted the formation of remarkable, dense, and stable char layer on wood as a barrier, retarding the spread of heat, oxygen, or flammable volatile and the further combustion of substrates. Besides, the free radical capture of phosphorus and the dilution effect of inert gas played an essential role in gas-phase flame retardancy.

Abstract not available