Search Results (396)

Wood coatings play a critical role in protecting wood substrates from environmental degradation, particularly ultraviolet (UV)-induced photodegradation. This review comprehensively examines the mechanisms of wood coating photodegradation, the factors influencing their durability, and current anti-aging strategies. Photodegradation arises from polymer chain scission, chemical structure reorganization, and photo-oxidation of lignin and cellulose, leading to coating chalking, cracking, gloss loss, and color changes, ultimately compromising wood mechanical properties and service life. Key anti-aging strategies include UV absorbers, which convert harmful UV radiation into heat; hindered amine light stabilizers (HALSs) that capture free radicals and quench excited-state molecules; barrier and shielding materials that form dense physical or nanostructured networks to block UV penetration and enhance mechanical and water resistance; and antioxidants that neutralize free radicals or decompose peroxides at the molecular level. Each approach can be employed individually or synergistically to enhance coating durability. Challenges remain in achieving long-term outdoor stability, balancing transparency and UV shielding, optimizing nanoparticle dispersion, and maintaining the activity of natural antioxidants. Future research should focus on multifunctional composite coatings integrating bio-based materials and nanotechnology, smart responsive systems, adaptive protection mechanisms, and standardized long-term evaluation protocols. These advancements will facilitate the development of high-performance, sustainable wood coatings and promote the value-added utilization of wood resources. Full article

The development of protective coatings that integrate self-healing and environmental tolerance is vital for extending substrate lifespan. In this study, a multifunctional hydrogel composite coating is developed based on a waterborne polyacrylate dynamic covalent network containing oxime–carbamate bonds. The functional monomer MEOC, which contains an oxime–carbamate dynamic bond, was synthesized and incorporated into the waterborne polyacrylate matrix to form a hydrogel network (OC-PA) with intrinsic self-healing capability. Prussian blue (PB) and nano-SiO₂ were incorporated to form a photothermal functional layer, imparting hydrophobicity and converting light into heat for de-icing, while also activating dynamic bond rearrangement within the substrate. When the MEOC content was 7 wt% and the PB content was 2 wt%, the coating temperature rose to 110 °C within 2 min under 0.6 W/cm² irradiation, and the scratch healed within 5 min. After 1 h of fracture repair, the tensile strength reached 6.68 MPa, with a repair rate as high as 92.91%, and de-icing time was reduced from 343 s to 183 s. The coating achieved a water contact angle >100°. At −20 °C, the icing delay time increased by 215%. The hydrogel coating also exhibited excellent abrasion resistance, chemical stability, UV aging resistance, and anti-fouling properties, offering a durable solution for demanding environments. Full article

In this work, poly(acrylic acid)-based layers were injected to form a sandwich layer between the cationic and anionic species for a compact and effective fire-retardant coating on cotton fabric using the layer-by-layer coating technique. From the SEM analysis, as the number of tri-layers increases, the attachment intensity increases, as can be seen for poly(acrylic acid) chitosan and bentonite clay PCB-5TL (the highest tri-layers), while in the case of halloysite-based coatings, as the number of tri-layers increases, instead of attachment, the agglomeration increases due to the high surface area of halloysite nanoclay tubes. FTIR and UV confirmed the finding from the new peak entry and an increase in thickness. The highest thermal residue, ~18%, was obtained for poly(acrylic acid) chitosan and halloysite nanoclay PCH-5TL with a maximum degradation peak intensity at ~389 °C. From the flammability and after-burning SEM investigation test, it was observed that the halloysite-based coating with a higher number of layers offered higher resistance against the flame spread and ignition and, thus, produced a higher amount of char. Full article

Background/Objectives: Gastro-resistant multiparticulate systems are designed to protect drugs in acidic environments and to ensure intestinal release. In practice, the method of administration may need to be modified: pellet-containing capsules opened or tablets halved for patients with swallowing difficulties, yet the type of liquid used for administration is often not specified. This study examined the stability of gastro-resistant coated pellets after exposure to various aqueous media prior to ingestion. Methods: To evaluate administration instructions, 103 Summaries of Product Characteristics of gastro-resistant products were reviewed. Pellets were produced using a bottom-spray fluidized bed process and coated with Eudragit L 30 D-55. Dissolution testing in pH 1.2 medium was performed after pre-soaking the pellets for 5, 15, and 30 min in beverages with various pH and conductivity. Drug release was measured by UV-VIS method, and morphological changes were assessed by image analysis. Marketed gastro-resistant products were also examined visually. Results: SmPC review revealed that the beverage for intake was frequently unspecified. Among the tested beverages differences in pH and conductivity were observed. Alkaline medicinal mineral waters induced increased and time-dependent premature drug release compared to tap and filtered water. Image analysis indicated a reduction in surface area after exposure to alkaline media. Conclusions: Contact with non-specified aqueous media before swallowing may weaken the protective function of gastro-resistant films. More explicit recommendations on suitable administration manipulation and media may improve therapeutic consistency. Full article

Developing materials that simultaneously exhibit bulk elasticity and a durable, self-renewing surface is a persistent challenge, as traditional fillers often impair flexibility and sacrificial coatings fail under repeated strain. This paper presents an innovative thiol–ene/polyurethane hybrid system, fabricated via a sequential thermal–UV curing process, which decouples the properties of the highly elastic bulk from those of the robust surface layer. The resulting bulk elastomer achieves an outstanding combination of high strength (20.9 MPa) and exceptional extensibility (990% elongation at break). Crucially, the UV-crosslinked surface forms a dense, abrasion-resistant shield that reduces friction-induced mass loss by 81% compared to the bulk material. This surface layer also exhibits a unique self-renewing capability, effectively restoring its protective function over at least three abrasion cycles and reducing mass loss by 57% after the first recovery cycle relative to an unprotected control. Dynamic mechanical analysis validates the distinct dual-network structure, evidenced by two well-separated glass transition temperatures, which underpin the material’s pronounced shape memory effect. This work provides a design paradigm for creating flexible and durable polymer systems with independently tailored bulk and surface properties, offering significant potential for applications in artificial skin and demanding flexible components. Full article

Titanium dioxide nanoparticles (TiO₂ NPs) are incorporated into automotive coatings to enhance durability, corrosion, UV resistance, and, in some formulations, photocatalytic self-cleaning. While the toxicology of pristine TiO₂ is well studied, the behavior of TiO₂ NPs embedded in polymer matrices and subjected to real-world aging, maintenance, and removal remains poorly characterized. This narrative review synthesizes 24 publications spanning the lifecycle of TiO₂ nano-enabled automotive coatings, from synthesis and formulation through application, in-service weathering, repair, refinishing, and end-of-life environmental fate. Upstream properties, such as coating functionality and performance, have been examined as determinants of later-life release, exposure, and fate. Across studies, dispersion state, interfacial compatibility, and surface modification—together with transformations such as agglomeration, photocatalysis, weathering, and eco-corona formation—shape particle stability, release, exposure relevance, and toxicological risk. Evidence indicates that sanding and accelerated weathering predominantly generate matrix-associated, polymer-fragment-dominated aerosols rather than pristine TiO₂ NPs, while NP-specific exposure measurements during spray application remain limited. Hazard data suggest matrix embedding may attenuate, but does not eliminate, biological responses relative to pure particles. Wastewater treatment plants and biosolids have been shown to act as sinks with potential for soil accumulation following sludge application. Regulatory frameworks rarely account for aging, transformation, and release, stressing the need for synchronized testing of aged materials and nano-specific exposure metrics to support safer-by-design coatings and risk governance. Full article

Polymer–ceramic hybrid composites are emerging as attractive candidates for lightweight, corrosion-resistant absorber components in solar thermal collectors; however, their adoption is constrained by the intrinsically low thermal conductivity of polymers, processing-induced anisotropic heat transport, interfacial thermal resistance at tube/laminate joints, and durability challenges under outdoor exposure. This review provides a collector-centered synthesis of polymer–ceramic hybrid materials, emphasizing the translation of composite properties into collector-level outcomes rather than conductivity enhancement alone. A structure–property–performance mapping approach is presented to connect directional thermal conductivity ((k_in-plane), (k_perp)), thermal diffusivity, heat capacity, coefficient of thermal expansion, and service temperature with collector performance parameters such as heat removal effectiveness, overall heat losses, and stagnation behavior. Ceramic fillers (e.g., boron nitride, aluminum nitride, silicon carbide, alumina) are examined for stable conduction-network formation, coating compatibility, and long-term reliability, while carbon fillers (graphite, graphene nanoplatelets, carbon nanotubes) are evaluated for combined heat spreading and solar absorption benefits, with attention to emissivity penalties. Hybrid ceramic–carbon architectures and multilayer absorber designs are identified as the most promising routes to balance thermal transport, optical selectivity (high solar absorptance and low thermal emittance), manufacturability, and durability under UV, humidity, and thermal cycling. Full article

Optical plastics possess excellent optical and mechanical properties but are limited by poor surface hardness and scratch resistance. Herein, UV-curable organic–inorganic hybrid coatings were developed to enhance scratch resistance while maintaining high optical transparency. Nano-silica sols were prepared via tetraethoxysilane (TEOS) hydrolysis and surface modified with silane coupling agents (KH-560, KH-570, and KH-550) to improve their dispersion and interfacial reactivity in a polyurethane acrylate (PUA) matrix. The modified nano-silica was incorporated into a UV-curable PUA system to fabricate transparent composite coatings. The influences of nano-silica type and loading on hardness, flexibility, wettability, scratch resistance, and UV–visible transmittance were systematically evaluated. Modified nano-silica markedly improved pendulum hardness and scratch resistance, with hardness increasing by nearly 50%, while flexibility remained nearly unchanged. Although hydrophobicity and optical transmittance slightly decreased with increasing nano-silica content, the transmittance remained above 90% at 4 wt% loading. For KH-550 modified systems, strict pH control (pH 8.0) and ammonia removal were critical for sol stability. This work offers a feasible approach for fabricating scratch-resistant, transparent UV-curable coatings for optical plastics. Full article

Superhydrophobic materials have clear potential for mitigating rain/humidity-induced damage to cultural heritage. In the present study, the wetting properties of Paraloid B72 were tailored to achieve superhydrophobicity by incorporating modified calcium carbonate (CaCO₃) nanoparticles (NPs). B72 is a well-established conservation product while CaCO₃ is chemically compatible with calcareous materials commonly found in cultural heritage buildings and objects. Initially, the wettabilities of CaCO₃ NPs, functionalised with caproic (C6), caprylic (C8), lauric (C12), myristic (C14), palmitic (C16), and stearic (C18) acid, were evaluated by measuring water contact angles (CAs) on NP pellets. For NPs with short hydrocarbon chains, CA increased with chain length, from 66.3° for CaCO₃-C6 to 118.0° for CaCO₃-C12 NPs. For NPs with longer chains, CA remained stable and around 118°. Based on these results, CaCO₃-C12 NPs were selected for further investigation and subjected to transmission electron microscopy analysis, which revealed chain-like agglomerates of aggregated nanocrystallites (5–10 nm) forming 40–150 nm polycrystalline NPs. Scanning transmission electron microscopy combined with elemental mapping revealed a homogeneous distribution of Ca, C, and O within the NPs. Next, CaCO₃-C12 NPs were dispersed in B72 solutions and sprayed onto limestone, which was employed as a model calcite-rich substrate. At optimal NP concentration, the resulting composite coating exhibited superhydrophobicity (CA > 150°), while it induced minimal colour alteration to limestone and effective resistance to capillary water absorption. The fluorine-free coating also demonstrated good durability against UV exposure, drop impact, salt attack, freeze–thaw cycles, tape peeling, drop pH variations, and thermal treatment. Full article

Fluorine-free paper coatings with water- and oil-resistance properties have gained considerable attention for sustainable food packaging applications. In this study, a dual-layer coating based on chitosan (Chi) and acrylated epoxidized soybean oil (AESO), both derived from renewable and natural resources, was applied to kraft paper. The ultraviolet-cured AESO top layer formed a dense crosslinking network, while the Chi interlayer promoted strong interfacial adhesion with the kraft paper through hydrogen bonding, effectively restricting fluid penetration. The Chi/AESO₄₀/kraft paper showed markedly enhanced water repellency and oil resistance, with a reduced Cobb₆₀₀ value of 16 g m⁻² and kit rating of 12. Thermogravimetric analysis demonstrated improved thermal stability, and mechanical testing results revealed enhanced packaging-relevant strength, with the tensile strength increasing from 33 to 40 MPa and tensile index increasing from 45 to 60 kPa·m² g⁻¹; furthermore, the burst strength and index improved from 260 to 330 kPa and from 3.2 to 4.0 kPa·m² g⁻¹, respectively. Food contact tests conducted using French fries confirmed the effective barrier performance of the Chi/AESO/kraft paper, highlighting its potential for use in sustainable paper-based food packaging applications. Full article

Nickel foam filtration layers used in sand control screens for petroleum extraction often suffer from insufficient mechanical strength and poor corrosion resistance and wear resistance. In this work, a two-stage electroplating strategy using the same metal was employed to construct hierarchical nickel coatings on nickel foam substrates. The effects of key process parameters, including electroplating time, temperature, and pretreatment, on the microstructure, mechanical properties, electrochemical corrosion behavior, and tribological performance of the coatings were systematically investigated. Electroplating time was found to directly regulate grain size and coating uniformity, while electroplating temperature significantly influenced nickel deposition behavior and electrolyte stability. In addition, UV pretreatment markedly improved the brightness and homogeneity of the deposited layers. Under optimized conditions (UV pretreatment for 10 min, electroplating at 60 °C for 8 min), a dense and uniform nickel coating with a well-ordered crystalline structure was obtained, leading to significantly enhanced hardness, wear resistance, and corrosion resistance. This study presents a practical and highly reliable approach for fabricating high-performance nickel-based coatings on nickel foam filter layers. Anticipated for application in the oil extraction industry, this method is set to enhance the performance of foam metal sand control layers. Full article

Perovskite quantum dots (PQDs) face significant performance limitations due to surface defects, which are not sufficiently addressed by conventional single-passivation methods. We introduce a dual-passivation strategy that synergistically combines bifunctional ligand 3-(N,N-dimethyloctadecylammonium)-propanesulfonate (SB3-18) treatment with silica coating to simultaneously passivate undercoordinated Pb²⁺ ions and bromine vacancies in red-emitting CsPb(Br/I)₃ PQDs. This approach nearly triples the photoluminescence quantum yield (PLQY, from 23% to 58%). Systematic structural, morphlogical, binding energy, Fermi level and optical analyses confirm effective defect suppression and enhanced exciton luminescence. The dual-passivated sample QDs:SB3-18@SiO₂ also exhibit excellent environmental stability, retaining 85% of their initial emission after 30 min in air and exhibiting improved UV resistance. By combining the PQDs with a CGSO:Tb³⁺ mechanoluminescent phosphor, a composite film is fabricated with bimodal optical response—color-selective photoluminescence under UV excitation and stress-activated green emission upon scratching. This work presents a robust route to high-performance PQDs and demonstrates their potential for advanced anticounterfeiting and smart optical applications. Full article

Civil engineering infrastructure suffers material degradation, shortened service life and high maintenance costs under harsh environments and natural aging, threatening public safety. Nanopolymer composites, featuring designable microstructures and excellent macroscopic properties, provide a revolutionary solution to improve the weather resistance and toughness of civil engineering materials. This paper systematically clarifies the modification mechanisms of nanocomposites, focusing on nanofiller–polymer matrix interfacial interactions (physical adsorption, chemical bonding) and their synergistic effects in enhancing environmental aging resistance (UV, corrosion, freeze–thaw) and mechanical performance (toughening, strengthening, dynamic load resistance). It summarizes the latest applications in nanomodified protective coatings, sealing/bonding materials and composite structural components, revealing the inherent “structure-property-application” relationships. Furthermore, this paper addresses core large-scale application challenges, including technical bottlenecks, performance evaluation limitations and economic/environmental barriers. Finally, future research directions are proposed, covering multifunctional intelligent materials, green development, interdisciplinary computational methods and standardized systems. This review offers an integrated perspective, providing theoretical guidance and practical references for advancing durable, resilient and sustainable civil engineering. Full article

Bamboo, a fast-growing biomass material with excellent mechanical properties, is widely used in furniture and construction. However, its susceptibility to moisture, cracking, and aging limits its durability. While acrylic resins offer good weather and water resistance, the relationship between resin formulation and the performance of bamboo remains unclear. This study developed a novel water-based styrene–acrylic resin tailored for bamboo, systematically investigating the relationships between resin formulation, coating structure, and performance. Results show that vinyltriethoxysilane-modified styrene–acrylic resin outperforms hydroxypropyl-acrylate-modified and unmodified styrene–acrylic. At a 10% dosage of vinyltriethoxysilane, the Zeta potential reached −24.2 mV, indicating enhanced emulsion stability. The coated bamboo exhibited a water contact angle of 100.56 ± 1.11°, a pencil hardness of 4H, and an adhesion grade of 1, significantly improving its waterproofing, hardness, and bonding strength. UV aging tests confirmed improved anti-aging performance, with optimal results at 10% dosage: color difference (ΔE) of 3.00 ± 1.81, dimensional change rate of 0.76 ± 0.22%, and gloss retention of 78%. This study also pioneers research on contact angle hysteresis for coated bamboo. The findings provide theoretical and technical support for developing high-performance bamboo coatings and durable outdoor bamboo products. Full article

Titanium-based implants are widely used in orthopedic and trauma surgery; however, postoperative infections remain a major cause of implant failure due to early bacterial adhesion. Localized antibiotic delivery from surface coatings offers a promising strategy to prevent initial colonization during the critical postoperative period. In this study, a self-organized TiO₂ nanotubular oxide layer was fabricated on Ti-407 by electrochemical anodization in a glycerol/NH₄F electrolyte at 40–60 V. SEM revealed vertically aligned single-walled nanotubes with diameters and lengths of ~80 nm and ~10 µm respectively. XPS analysis verified TiO₂ formation with Al–O, V–O, and fluorine incorporation. Ceftriaxone was successfully loaded into the nanotubular structure, as identified by FT-IR. UV–Vis measurements showed a biphasic release profile consisting of an initial burst followed by sustained release determined by nanotube geometry. In vitro antibacterial activity was evaluated against Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli using optical density, CFU quantification, and an agar diffusion assay. Unloaded surfaces showed no inhibition, whereas ceftriaxone-loaded nanotubes significantly reduced bacterial growth up to ~6% and generated clear inhibition zones. These findings demonstrate, for the first time, that TiO₂ nanotubular coatings derived from Ti-407 support drug loading and demonstrate effective in vitro antibacterial activity, highlighting their potential for infection-resistant orthopedic implants. Full article