Search

To improve the anti-sticking performance of tire molds, six types of coatings (i.e., nano-ceramic coating, bilayer waterborne polytetrafluoroethylene (PTFE) coating, fluorinated ethylene propylene (FEP)-based Whitford coating, PTFE, FEP, and perfluoroalkoxy (PFA) aqueous dispersions) were selected to modify type-45 steel specimens by air spraying. Their wettability, microstructure, demolding force, and anti-fouling properties in rubber vulcanization tests were studied. The results show that the demolding forces of the coatings were at least 24% lower than that of uncoated surface. Whitford coating, PFA, and FEP coatings had zero demolding force and no pollutant residue. PTFE coating had no pollutant residue but had high demolding force. The other two coatings had poor anti-sticking property. Upon combining the surface morphology and chemical composition analysis results, the coating demolding force was related to the surface micro-morphology: smoother surfaces led to lower demolding forces, while the surface chemical composition had a direct influence on the rubber contaminant residual. The C–F bonds on the surfaces resulted in less rubber residual due to intrinsic low surface energy. X-ray photoelectron spectrometry (XPS) analysis showed that ZnS was one of the main pollutants after rubber vulcanization test.

Controlled self-assembly of plasmonic photonic nanostructures provides a cost-effective and efficient methodology to expand plasmonic photonic nano-platforms with unique, tunable, and coupled optical characteristics. Keeping advantages and challenges in view, this review highlights contemporary advancements towards the development of self-assembly of a plasmonic photonic nanostructure using a colloidal solution and a self-assembly modeling technique along with exploring novel optical properties and associated prospects. The potential applications of self-assembled plasmonic photonic nano-systems to investigate next-generation optoelectronic devices, the need to reduce and increase scaling up aspects, and improve the performance, are also covered briefly in the review. The need of considerable efforts for the design and development towards establishing novel cost-effective methods to fabricate controlled self-assembled smart nano-plasmonic platforms is also highlighted in this mini-review. Key confronting issues that precisely limit the self-assemblies of photonic nanostructures and desired integration with other device components, mainly including uniformity within miniaturized devices are also discussed. This review will serve as a guideline and platform to plan advanced research in developing self-assembled plasmonic photonic nano-systems to investigate smart functional optical devices.

Nowadays, high-entropy alloys (HEAs) have become a hot research topic in the field of coating materials. However, HEAs have a large wide range of compositional systems, and the differences in their composition inevitably lead to the significant variations in the matching process parameters of laser cladding and post-treatment methods, which in turn give the coatings a broad range of microstructures and protective properties. Therefore, it is crucial to review and summarize the research progresses on laser cladding HEA coatings to provide a reference for obtaining high-performance HEA coatings and further expand the application of HEA coatings. This work describes the working mechanism of laser cladding and illustrates the advantages and drawbacks of laser cladding in detail. The effects of the addition of alloying elements, process parameters and post-treatment techniques on the microstructures and properties of the coatings are thoroughly reviewed and analyzed. In addition, the correlations between the chemical compositions of HEAs, process parameters of laser cladding, post-treatment techniques and the microstructure and protective properties of the coatings are investigated and summarized. On this basis, the future development direction of HEA coatings is outlined.

A thorough experimental investigation of polymer-glass transition temperature (Tg ) is performed on poly(vinyl alcohol) (PVA) and fumed silica nanoparticle (SiNP) composite. This is done together with atomistic molecular dynamics simulations of PVA systems in contact with bare and fully hydroxylated silica. Experimentally, PVA-SiNP composites are prepared by simple solution casting from aqueous solutions followed by its characterization using Fourier-transform infrared spectroscopy (FTIR), dynamic mechanical analysis (DMA), and dynamic scanning calorimetry (DSC). Both theoretical and experimentally deduced Tg are correlated with the presence of hydrogen bonding interactions involving OH functionality present on the surface of SiNP and along PVA polymer backbone. Further deconvolution of FTIR data show that inter-molecular hydrogen bonding present between PVA and SiNP surface is directly responsible for the increase in Tg . SiNP filler and PVA matrix ratio is also optimized for a desired Tg increase. An optimal loading of SiNP exists, in order to yield the maximum Tg increase arising from the competition between hydrogen bonding and crowding effect of SiNP.

In this paper, sol–gel-based transparent easy-to-clean (ETC) coatings are fabricated using organic–inorganic hybrid precursors and fluorinated silane-based hydrophobic surfactants. ETC coatings were applied on different plastic materials such as polycarbonate, poly(methyl methacrylate) and polyethylene terephthalate. Due to the low temperature resistance of the plastic materials, usually lower than 120 °C, low temperature processes such as ammonia gas curing and ultraviolet irradiation curing were employed for coatings development. Alumina nanoparticles were used to improve the mechanical properties of the coatings, and antimicrobial effect was realized by incorporation of silver nanoparticles, and high bacterial killing rates were obtained with very low silver concentration (50 ppm). All the coatings developed on different substrates show high water/hexadecane contact angles with good wet scrubbing resistance. Abrasion-resistant multifunctional sol–gel coating on PMMA substrate

Star-like polyurethane (PU) hybrid films containing octafunctional cubic silsesquioxanes are prepared by polyaddition reaction between octakis(dimethylsilyloxy) silsesquioxane isopropenyldimethylbenzyl isocyanate (OS-PDBI) and octakis(dimethylsilyloxy) hydroxypropyl silsesquioxane (HPS); and between OS-PDBI and hexane diol (HD). The effect of incorporation of nanostructured cubic silsesquioxanes (CSSQ) on the macroscopic properties of PU film and their thermomechanical properties are investigated. The obtained hybrid films are relatively transparent. Their morphologies and properties are studied by using Fourier transform infra-red spectroscopy (FTIR), X-ray diffraction (XRD), atomic force microscopy (AFM), thermogravimetry (TGA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and contact angle measurements. The formation of urethane linkage disrupts the three-dimensional ordered structure of CSSQ in the hybrid film. AFM images show clearly that no phase separation in the macroscopic level for both PU hybrid films. TGA and DMA analyzes indicate that the incorporation of octafunctional silsesquioxane in PU hybrid film provides enhanced thermal stability and increased crosslink density. Moreover, the existence of cage structure also improves oxidation resistance and mechanical strength. The incomplete reaction between OS-PDBI and HPS due to the steric hindrance of highly branched rigid CSSQ could result in a slight decrease in initial decomposition temperature. Furthermore, hardness and out-of-plane compressive modulus are also investigated by nanoindentation.