Progress in Organic Coatings最新文献

In this study, a double-layer composite coating was developed by integrating a superhydrophobic top layer with a smart self-healing bottom layer. The superhydrophobic top coating demonstrated a high water contact angle of up to 153°, showcasing excellent mechanical properties, corrosion resistance, self-cleaning ability, and resistance to fouling, ice formation, and scaling. Notably, the anti-scaling property of the coating remained above 80 % after 36 h of immersion. The bottom layer, composed of waterborne epoxy resin and pH-responsive smart fillers, provided enhanced corrosion resistance and self-repairing capabilities while maintaining environmental friendliness. Experimental results indicated that the impedance value of the composite coating could reach 10¹⁰ Ω·cm² at 0.01 Hz, significantly surpassing the corrosion resistance of traditional waterborne epoxy resin coatings. Additionally, the protective effect of the superhydrophobic top layer was evident even after the coating was damaged, suggesting a novel approach for employing superhydrophobic coatings in metal corrosion protection.

This paper reports on an essential step towards accelerating the development of new, environmentally friendly active protective coatings by structure optimization. The complex microstructure of the pigment particles within a coating have been observed non-destructively in 3D by nano-computed tomography using synchrotron radiation. For the first time, a stochastic geometry model is fitted based on spatial geometric features of the particles observed in the 3D images. The typical cell of a random Gibbs-Laguerre tessellation is used to model the particles' polyhedral shapes as well as the observed joint size and aspect ratio distributions.

Coatings with superamphiphobicity and photocatalytic degradation properties to achieve excellent self-cleaning performance have received extensive attention. Herein, TiO₂-SiO₂ composite particles with micro-/nanoscale hierarchical structures were fabricated by hydrophobic agglomeration. The TiO₂-SiO₂ was modified with 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane (PFDTS), and then it was sprayed onto the surfaces of substrates to obtain TiO₂-SiO₂/PFDTS coatings. The coating surface exhibited superamphiphobicity and low adhesion properties. The contact angles (CAs) of water, ethylene glycol, glycerol, and hexadecane on the coating surface were 163.5°, 154.6°, 157.3°, and 150.2°, respectively. The slide angles (SAs) of the above droplets on the coating surface were 0.4°, 2.7°, 1.6°, and 11.1°, respectively. In addition, 80.9 % methyl orange solution (10 ppm) was degraded by the TiO₂-SiO₂/PFDTS under UV irradiation in 60 min, demonstrating an excellent photocatalytic degradation performance. It also had good adaptability to different substrates, liquids with different properties, and outdoor environments. The results of a mechanistic study showed that SiO₂ and TiO₂ were connected by the carbon chains of modifiers. PFDTS and TiO₂-SiO₂ might be combined by chemical bonds or surface carbon chains. The hierarchical structure of TiO₂-SiO₂ and the low surface energy of PFDTS resulted in the superamphiphobic property of the TiO₂-SiO₂/PFDTS coating.

Functional polyvinylethylene glycols (PVEGs) with different central structures were synthesized by Pd/B synergistic catalysts and reacted with isophorone diisocyanate (IPDI) and 2-hydroxyethyl methacrylate(HEMA) to prepared pendent vinyl-functional polyurethane acrylates (VFPUAs). The photopolymerization of the obtained VFPUAs with pentaerythritol tetra(3-mercaptopropionate) (PETMP) in the presence of a photoinitiator proceeded smoothly via thiol-ene photo-click reaction to give a series of crosslinked materials by the variation of the chemical structure of VFPUAs and a ratio of thiols and enes. The curing behavior was studied by FT-IR and the properties of crosslinked materials were characterized by the test of gel content, swelling ratio and water absorption. The dynamic mechanical properties, mechanical properties, thermogravimetry and surface properties of the crosslinked materials were investigated and the performance of coating for the crosslinked film materials was also characterized. The crosslinked film materials can be further functionalized by post-crosslinking modification through thiol-ene photo-click reaction.

Food packaging is developing towards more environmentally friendly polymer matrix and superior active functions. In this study, polyvinyl alcohol (PVA) based active coating incorporating chlorogenic acid (CGA) and CGA functionalized layered clay (LDHs@CGA) was applied to construct polylactic acid (PLA) three-layer active films on fully biodegradable PLA base film. The results indicated that PVA based active coating using dual coating technology (LDHs@CGA/PVA + CGA/PVA) had no visible interface and a uniform thickness, ranging from 4 to 5 μm. When the amount of LDHs@CGA was 1 wt%, the release of CGA in the active intermediate layer (CGA/PVA coating) was limited due to the natural barrier of LDHs@CGA in the controlled release layer (LDHs@CGA/PVA coating), resulting in a decrease in active functions. When the amount of LDHs@CGA reached 3 wt%, the antioxidant (DPPH method), antibacterial (Escherichia coli), and UV absorption (at 335 nm) reached 85.6 %, 87.2 %, and 73.2 %, respectively. This was because in addition to CGA as the main active substance, sufficient amounts of LDHs@CGA can also serve as secondary active substance to supplement the release of CGA. Meanwhile, the addition of LDHs@CGA could significantly improve the gas barrier properties of PVA based active coating, and the barrier to oxygen was much higher than that to water vapor. This study proposes a method of constructing PLA three-layer active films by coating with PVA based active inner coating, which can more effectively and stably exert the active functions for food packaging applications.

Self-healing microcapsules represent a highly promising strategy for enhancing the long-term durability of materials under prolonged service conditions. Nevertheless, the industrial application of microcapsules encounters significant challenges. This is primarily due to the dilemmas involved in guaranteeing effective repair without significantly undermining the intrinsic properties of the substrate materials. Inspired by the structure of honeycombs, this paper introduces a bilayer, nested, porous self-healing microcapsule featuring an ultra-thin, rigid shell that effectively addresses the above challenges. An ultra-thin rigid shell is first constructed to enhance mechanical strength while significantly increasing the load capacity of the healing agent. Subsequently, the subcritical water treatment method is employed to etch nanoscale through-holes on the shell surface for encapsulating the healing agent. Finally, via a cross-linking reaction, a film is formed on the surface of the porous shell to seal the holes. The test results show that the loading efficiency of the microcapsules achieves 94.4 %. Moreover, while the repair efficiency is substantially enhanced, the intrinsic properties of the matrix material are maintained, and there is additionally a measurable improvement in tensile strength and insulation performance. To our knowledge, the microcapsules that significantly enhance repair efficiency while concurrently improving the properties of the matrix have not yet been reported in previous studies.

In the realm of biomedical applications, biocompatible materials with optimized surface properties are crucial for facilitating cellular interactions. To attain the perfect balance of these properties, surface modification of non-toxic and stable bulk materials is often required. Within this context, this research aimed to improve the physiochemical and cell-responsive properties of a low-density polyethylene film. This was achieved by depositing thiol-rich coatings using a dielectric barrier discharge plasma reactor operating at medium pressures, with 1-propanethiol serving as polymerization precursor. The study systematically investigated the impact of key plasma polymerization parameters, including DBD chamber pressure, treatment time, and the combination of precursor flow rate and discharge power represented by the Yasuda parameter, to identify optimal plasma processing conditions for the formation of thiol-rich coatings. To characterize the coating thickness, hydrophilicity and surface chemical composition, atomic force microscopy, water contact angle measurements, and X-ray photoelectron spectroscopy were employed. The findings indicated that reducing the chamber pressure to 10 kPa led to more hydrophilic and thicker deposits possessing a higher sulphur content. Deposition time (5 to 15 min) also significantly impacted coating thickness and surface chemistry, where long times increased thickness, but also led to a reduced sulphur and increased oxygen content because of more pronounced etching. The optimal deposition time was therefore set at 10 min resulting in the deposition of dense coatings possessing a high number of sulphur-containing functionalities. The Yasuda parameter (W/FM) analysis demonstrated optimal thiol incorporation in combination with high coating stability at an intermediate W/FM value of 72 MJ/kg. Following the determination of the optimal plasma polymerization parameters, the effectiveness of thiol plasma polymerization and subsequent fibronectin immobilization for enhancing cell adhesion and proliferation was investigated. The thiol-coated substrates were found to exhibit superior protein immobilization, because of the high affinity for protein binding of the available thiol groups. To assess cellular responses, Schwann cells were cultured on uncoated and coated samples before and after fibronectin immobilization. The results revealed a superior cellular response of the thiol-coated samples after fibronectin immobilization, showing the highest cell viability and significantly enhanced cell adhesion and proliferation. Collectively, these results underscore the synergistic effect of thiol plasma polymerization and fibronectin immobilization in promoting the cellular response of LDPE substrates, thus highlighting their potential as a surface modification strategy of biomaterials.

The antibacterial ability of an implant is governed by the interaction between the surface of the material and the cells. Nanosized features that promote bacterial killing were achieved through synthesizing a Zn/graphene/chitosan surface on a NiTi alloy. The surface morphology and microstructure of the Zn/graphene/chitosan surfaces were observed, and their antibacterial behavior was investigated. The Zn/graphene/chitosan surface exhibited 93 % antibacterial activity against Staphylococcus aureus (S. aureus), which was higher than the Zn/chitosan surface (67 %), and it inhibited bacterial adhesion. This was attributed to the fast release of Zn ions from the Zn/graphene/chitosan surfaces and the sharp morphology of graphene on the surface. In addition, the adhesion of the Zn/graphene/chitosan coating increased with the amount of graphene content. This finding suggests that the synergy of graphene improves the antibacterial ability, bioactivity, and adhesion of Zn-containing coatings.

Light Detection and Ranging (LiDAR) is the major sensor for autonomous vehicles. It emits near-infrared (NIR) pulsed light at 905 nm and detects the reflected portion of this light from the surrounding objects. Location and surface determination of the surrounding objects is performed using the time-of-flight (the elapsed time from launch of a pulsed beam to detection of the reflected returned beam). Solvent borne acrylic paints gained wide currency for the exterior automotive coatings over the years and topcoats with conventional dark-colored pigment dispersions exhibit low reflectivity in the NIR region. The formulation of innovative topcoats with high reflectivity in this region is an urgent task for leading paint manufacturers. In this study, pigment dispersions to be incorporated in LiDAR-detectable solvent borne acrylic automotive topcoats were designed considering the surface charges of individual pigment particles for dispersant selection. Stability of designed dispersions was demonstrated and color matching studies were realized. Three dark colors encoded RAL 9011 (Graphite black), RAL 5017 (Traffic blue), and RAL 5015 (Sky blue) from the RAL 841-GL color chart were formulated as acrylic topcoats with NIR reflective pigments. Based on the surface properties of the dry films, such as gloss, haze and distinctness of image, a significant increase in LiDAR detection was achieved for each color. The results affirmed the potential use of the developed formulations as end-product paints for coating the exterior surfaces of autonomous vehicles.

Non-degradable coatings made of petroleum-based plastics hinder the degradation performance of products. This highlights the urgent need to develop biodegradable, bio-based coatings derived from renewable resources to create a more sustainable and greener world with a smaller environmental footprint. This study endeavours to examine the effects of beeswax and coconut oil additions on the morphological, degradation, and water-barrier properties of mycelium-based composite (MBC). Coconut oil is supplemented with varying amounts of beeswax, comprising 0, 20, 40, 60, 80, and 100 wt%. Dip coating is applied to prepare coated-MBC at 65 °C for 2 min. The coated-MBC is characterized by water absorption test, water loss measurement, density measurement, yeast and mould test, shrinkage measurement, weight loss measu rement, soil burial test, Scanning Electron Microscopy (SEM) and macroscopic appearance. Findings revealed that a higher composition of beeswax (80 BW) leads to lower water absorption ability (26.25 %) and no fungal growth for 36 days, in contrast to uncoated-MBC (0 BW), which are used as a reference sample.