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Influence of silane coupling agent on the properties of UV curable SiO2-PMMA hybrid nanocomposite
摘要： This work reports the preparation of UV-curable organic–inorganic hybrid nanocomposites synthetized by sol–gel method with the aim of obtaining highly transparent anti-abrasive coatings with long-term storage and stability for the protection of organic light emitting diodes (OLEDs). The inorganic phase is composed of tetraethoxysilane (TEOS) condensed under acid catalysis and mixed with tetrafunctional acrylate monomer and oligomer. Vinyltriethoxysilane (VTES), 3-methacryloxypropyltrimethoxysilane (MEMO), and 3-mercaptopropyltriethoxysilane (MTMO) are used as silane coupling agent and hybrid network modifier. Among the various parameters influencing the structure and properties of the hybrid, this work focuses on the nature and amount of coupling agent and their influence in terms of transparency, mechanical properties, and stability of the formulation. An optimum can be found in the silica to coupling agent ratio. Low level of functionalization leads to hybrids displaying poor optical performances and stability due to the coalescence of silica domains. On the contrary, an excess of functionalization reduces the abrasion resistance and the silica network formation. Changing the organic pendant of coupling agents greatly influences the properties of the coating by promoting the organic–inorganic balance. Dense and flexible as well as mechanically resistant coatings can be obtained from similar formulation by simply tuning the nature of the coupling agent depending of the needs of the application.
关键词： Sol–gel,Abrasion resistance,Nanocomposite,Hybrid coatings,UV-curable
更新于2025-09-04 15:30:14
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Significant improvement of the performance of ZrO2/V1-W O2/ZrO2 thermochromic coatings by utilizing a second-order interference
摘要： The paper deals with VO2-based thermochromic coatings prepared by reactive magnetron sputtering. We combine four ways how to improve the coating performance and to increase its application potential. First, reactive high-power impulse magnetron sputtering with a pulsed O2 flow control allowed us to prepare crystalline VO2 of the correct stoichiometry under highly industry-friendly deposition conditions: without any substrate bias at a low deposition temperature of 330 °C. Second, doping of VO2 by W (leading to V1-xWxO2, with x = 0.012 in this work) allowed us to shift the thermochromic transition temperature towards the room temperature (39 °C in this work), without concessions in terms of coating properties. Third, we employ ZrO2 antireflection layers both below and above the thermochromic V1-xWxO2 layer, and present an optimum design of the resulting ZrO2/V1-xWxO2/ZrO2 coatings. Most importantly, we show that while utilizing a first-order interference on ZrO2 leads one to a tradeoff between the luminous transmittance (Tlum) and the modulation of the solar transmittance (ΔTsol), utilizing a second-order interference allows one to optimize both Tlum and ΔTsol in parallel. Fourth, the crystalline structure of the bottom ZrO2 layer further improves the VO2 crystallinity and the process reproducibility. The optimum experimental values of ZrO2 thickness are in agreement with those predicted during the coating design. The results are important for the design and low-temperature fabrication of high-performance durable thermochromic VO2-based coatings for smart window applications.
关键词： Thermochromic coatings,Low deposition temperature,Antireflection layer,HiPIMS,Doping,VO2
更新于2025-09-04 15:30:14
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<i>In Situ</i> IR Spectroscopy of Mesoporous Silica Films for Monitoring Adsorption Processes and Trace Analysis
摘要： Adsorption of molecules on high-surface-area materials is a fundamental process critical to many fields of basic and applied chemical research; for instance, it is among the simplest and most efficient principles for separating and remediating polluted water. However, established experimental approaches for investigating this fundamental process preclude in situ monitoring and thus obtaining real-time information about the ongoing processes. In this work, mid-infrared attenuated total reflection (ATR) spectroscopy is introduced as a powerful technique for quantitative in situ monitoring of adsorption processes and thus enrichment of traces of organic pollutants from aqueous solution in ordered mesoporous silica films. The synthesis, functionalization, and characterization of two silica films with 3D hexagonal and cubic pore structure on silicon ATR crystals are presented. Benzonitrile and valeronitrile as model compounds for aromatic and aliphatic water pollutants are enriched in hydrophobic films, while the matrix, water, is excluded from the volume probed by the evanescent field. Enrichment times of <5 s are observed during in situ measurements of benzonitrile adsorbing onto the film from aqueous solution. The sensing system is calibrated using the Freundlich adsorption equation as a calibration function. Enrichment factors of benzonitrile and valeronitrile within the film were determined to be >200 and >100, respectively, yielding detection limits in the low ppm range. Furthermore, fast and complete desorption of the analyte, ensuring reliable regeneration of the sensor, was verified. Lastly, we derive and experimentally validate equations for ATR spectroscopy with thin film adsorption layers to quantify the absolute mass of adsorbed pollutant in the film. The excellent agreement between recorded absorptions at target wavenumbers of the target analytes and corresponding simulations corroborates the validity of the chosen approach.
关键词： infrared spectroscopy,functional coatings,sensor,porous materials,thin film
更新于2025-09-04 15:30:14
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Facile spraying fabrication of highly flexible and mechanically robust superhydrophobic F-SiO <sub/>2</sub> @PDMS coatings for self-cleaning and drag-reduction applications
摘要： Superhydrophobic coatings treated as surface functional materials are endowed with great application potential with respect to self-cleaning, drag-reduction, anti-icing, etc. In this study, we fabricated a highly flexible and mechanically robust superhydrophobic F-SiO2@PDMS coating through a facile layer-by-layer strategy. It was demonstrated that PDMS played a crucial role of binder for immobilizing the F-SiO2 nanoparticles and improving their adhesion to substrate materials. Meanwhile, the PDMS layer endowed the superhydrophobic coating with superior mechanical flexibility. Finally, the as-constructed superhydrophobic coating exhibited excellent water-repellency with a high water contact angle of 156.5° and low sliding angle of only 2.0°. Furthermore, the water adhesion strength on the superhydrophobic coating was only 2 mN, indicating its ultralow viscous resistance to dynamic moving water droplets. The superhydrophobic F-SiO2@PDMS coating was independent of the substrates without any limitations, and they exhibited high flexibility and mechanical robustness with the elongation ratio reaching 83.3% under the conditions of high superhydrophobicity. Also, the superhydrophobic coating exhibited strong durability under the severe environments of corrosion and mechanical abrasion. Thus, the as-fabricated highly flexible and mechanically robust superhydrophobic F-SiO2@PDMS coating is considered to be an ideal candidate for applications in the fields of self-cleaning and drag-reduction.
关键词： F-SiO2@PDMS,drag-reduction,mechanical robustness,superhydrophobic coatings,self-cleaning
更新于2025-09-04 15:30:14
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Thin Film Processes - Artifacts on Surface Phenomena and Technological Facets || Layer-by-Layer Thin Films and Coatings Containing Metal Nanoparticles in Catalysis
摘要： The layer-by-layer (LbL) technique is one of the most promising ways of fabricating multilayer thin films and coatings with precisely controlled composition, thickness, and architecture on a nanometer scale. This chapter considers the multilayer thin films and coatings containing metal nanoparticles. The main attention was paid to LbL films containing metal nanoparticles assembled by convenient methods based on the different intermolecular interactions, such as hydrogen bonding, charge transfer interaction, molecular recognition, coordination interactions, as driving force for the multilayer buildup. Much attention has paid to the LbL films containing metal nanocomposites for multifunctional catalytic applications, in particular, photocatalysis, thermal catalysis, and electrocatalysis. The preparation protocol of LbL-assembled multilayer thin films containing metal nanoparticles (such as Au, Ag, Pd, Pt), metal oxides (Fe3O4), and sulfides (CdS) that are supported on the various surfaces of nanotubes of TiO2, Al2O3 membranes, graphene nanosheets, graphene oxide and further applications as catalysts with respect to photocatalytic, electrocatalytic performances is discussed. The systematization and analysis of literature data on synthesis, characterization, and application of multilayer thin films and coatings containing metal nanoparticles on the diverse supports may open new directions and perspectives in this unique and exciting subject.
关键词： semiconductors,metal nanoparticles,polyelectrolytes,layer-by-layer assembling,thin films and coatings,immobilization,catalysts
更新于2025-09-04 15:30:14
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Thermal Shock Resistance of Thermal Barrier Coatings with Different Surface Shapes Modified by Laser Remelting
摘要： Inspired by the unique structures and shapes of biological organisms, thermal barrier coatings (TBCs) with different shapes including dot, striation and grid were modified by laser remelting. NiCrAlY/ZrO2-7 wt.%Y2O3 double-layer-structured TBCs were prepared. The microstructure, microhardness, phase composition and thermal shock behaviors of the as-sprayed and laser-treated specimens with different shapes were examined. The results indicated that the unit was characterized by the dense columnar crystal structure and the high microhardness. The thermal cycle lifetime of the dotted specimen was about twice that of the as-sprayed specimen. On the one hand, due to the elimination of defects and higher hardness after laser remelting, the dotted unit could resist thermal crack propagation. On the other hand, the columnar grains and segmented cracks in the dotted units were beneficial to increase the strain tolerance. However, due to more continuous segmented cracks and transverse cracks, the striated and grid specimens had relatively poor thermal shock resistance.
关键词： laser remelting,thermal barrier coatings,thermal shock resistance,surface shape
更新于2025-09-04 15:30:14
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Cu-Doped TiO2: Visible Light Assisted Photocatalytic Antimicrobial Activity
摘要： Surface contamination by microbes is a major public health concern. A damp environment is one of potential sources for microbe proliferation. Smart photocatalytic coatings on building surfaces using semiconductors like titania (TiO2) can effectively curb this growing threat. Metal-doped titania in anatase phase has been proven as a promising candidate for energy and environmental applications. In this present work, the antimicrobial efficacy of copper (Cu)-doped TiO2 (Cu-TiO2) was evaluated against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) under visible light irradiation. Doping of a minute fraction of Cu (0.5 mol %) in TiO2 was carried out via sol-gel technique. Cu-TiO2 further calcined at various temperatures (in the range of 500–700 ?C) to evaluate the thermal stability of TiO2 anatase phase. The physico-chemical properties of the samples were characterized through X-ray diffraction (XRD), Raman spectroscopy, X-ray photo-electron spectroscopy (XPS) and UV–visible spectroscopy techniques. XRD results revealed that the anatase phase of TiO2 was maintained well, up to 650 ?C, by the Cu dopant. UV–vis results suggested that the visible light absorption property of Cu-TiO2 was enhanced and the band gap is reduced to 2.8 eV. Density functional theory (DFT) studies emphasize the introduction of Cu+ and Cu2+ ions by replacing Ti4+ ions in the TiO2 lattice, creating oxygen vacancies. These further promoted the photocatalytic efficiency. A significantly high bacterial inactivation (99.9999%) was attained in 30 min of visible light irradiation by Cu-TiO2.
关键词： Staphylococcus aureus,phase transition,antibacterial coatings,photocatalysis,doping,Cu-doped TiO2,Escherichia coli
更新于2025-09-04 15:30:14