Journal of Coatings Technology and Research最新文献

Space exploration has burgeoned into a billion-dollar industry, pushing the boundaries of human knowledge in various fields. The prospect of space stations being accessible to part of the population by the end of the century is within reach. However, the bacterial ecology in these stations poses a significant threat, as the hostile environment may increase the mutation rate, potentially leading to new pandemics upon return to Earth. One proposed mitigation strategy is the development of bactericidal surfaces that prevent bacteria from adhering and promote their inactivation. Bioinspired approaches offer promising solutions given their efficiency, cost-effectiveness, and environmental friendliness. This paper conducts a comprehensive literature review on bacteria in the space environment, using the International Space Station as a reference. In addition to presenting a brief overview of various bactericidal coating strategies currently studied or employed, three specific production approaches are examined in more detail: antimicrobial peptide coatings, quaternary ammonium compound coatings, and nanostructured surfaces that promote bacterial lysis. The study concludes that while antimicrobial peptides are susceptible to radiation and quaternary ammonium compounds raise concerns about genotoxicity, nanostructured surfaces emerge as a robust solution due to their structural stability and immense potential for applications in the aerospace industry.

Residual stresses can be easily generated during the manufacturing of thin films/coatings due to deformation mismatches. The presence of residual stress may induce issues such as premature cracking and shedding, ultimately affecting the mechanical performance and service life of these materials. Consequently, measurement of residual stresses in thin films/coatings is of great importance to ensure their reliability in applications. Instrumented indentation, as a sophisticated micro/nano scale testing technique, proves highly effective for measuring residual stress in thin films/coatings due to its exceptional resolution and non-destructive characteristics. This review provides a comprehensive discussion and summary on the current instrumented indentation models for determination of residual stresses, including their advantages and limitations. Furthermore, the trends for future development and possible challenges were also given. For the current models, challenges mainly originate from preparing stress-free thin film/coating samples as reference samples, determining the directionality of non-equibiaxial residual stresses, as well as eliminating the influence of substrates on the measurement accuracy. Thus, there is an increasing demand to establish an instrumented indentation model capable of decoupling substrate effects and accurately measuring non-equibiaxial residual stresses in thin films/coatings without using reference samples.

Phosphazene modifiers based on hexachlorocyclotriphosphazene and various ratios of phenol and bisphenol A were synthesized and used to increase the fire resistance of epoxy coatings. The structure of all modifiers was confirmed by NMR spectroscopy and it was shown that all products represent the mixtures of hexa- and pentasubstituted cyclotriphosphazenes. All the modifiers were mixed with epoxy resin and the obtained coatings were studied. The addition of phosphazene modifiers did not affect coating properties such as adhesion, impact strength and elasticity. On the other hand, the modifiers led to an increase in the fire resistance of the coatings. It was shown that increased bisphenol A content led to a decrease in fire retardant efficiency. The best results were shown with modifier having phenol/bisphenol A ratio of 5:1 at a concentration in epoxy resin of 5 wt%.

Graphical Abstract

Scientists mimic nature to create diverse biomimetic superhydrophobic surfaces, emulating the remarkable features of organisms and plants. Synthetic superhydrophobic cotton fabrics have garnered significant interest due to their water-repellent properties and versatile applications. This paper provides a complete summery of current development in this field, encompassing surface modification techniques, coating materials, and uses. It delves into fabrication techniques and points out future research directions. Superhydrophobic surfaces require low energy and high roughness, achieved through chemical and physical processes, offering features like self-healing and bacterial resistance. The review summarizes recent research and outlines potential applications, offering insights for future research and practical utilization of these materials.

Applying a chemical substance known as an antimicrobial coating kills pathogenic microorganisms such as fungi, yeasts, bacteria, and molds, and inactivation of viruses. Since some conventional coatings may require high temperatures but sol–gel coating can be completed at low temperatures, it is an easy coating technique for adding antimicrobials to polymeric surfaces. Various antimicrobial compounds used in sol–gel coating preparation have two categories: 1) Chemical compounds such as TiO₂, Ag, ZnO, CaO, Si, MgO, Au nanoparticles and boron nitride, biocides, hydroxyapatite, and 2) natural compounds such as bioactive liquids and curcumin. Antimicrobial compounds act as a mechanism for forming the reactive oxygen species (ROS), reducing the potential of DNA to duplicate itself, and tRNA interaction with the ribosome is suppressed, disrupting antimicrobial enzyme activity, releasing of ions, preventing bacterial adhesion, and modulation of microbial gene expression. Antimicrobial sol–gel coatings can be applied to the film substrate by dipping, spraying, or spinning processing before gelation. Numerous uses, including textiles, biomedical applications, packaging, glass substrates, metals like silver, copper, zinc, and nickel, and the avoidance of biofilm development, have made application of antimicrobial sol–gel films. Nonetheless, it is frequently utilized in the textile sector to stop microbiological contamination, shield biofouling, and lessen perspiration odor. This paper presents and discusses the various antimicrobial compounds with their antimicrobial mechanism and various applications of coatings obtained from sol–gel.

Graphical abstract

The production of graphite/graphene derivative inks, incorporating different solvents, binders, and stabilizers is a focused research area for the development of printed electronic circuits on flexible substrates. Within the scope of the present study, a facile methodology was employed to produce a water-based graphite paste, devoid of binders and stabilizers, serving as a conductive paste while preserving the unique properties of graphite. A superior adhesive graphite thin film, attaining a 5B standard according to the ASTM D3359 crosshatch adhesion test, was successfully developed on a polyimide substrate (PI). This graphite coating on polyimide (Gr/PI) was characterized using mechanical reliability tests and four-probe resistance measurements. The adhesive Gr/PI exhibited an optimal sheet resistance value of 114 ± 12 Ω/sq/mil. The shifts in the FTIR of Gr/PI, compared to the spectrum of PI indicate significant π-π interactions between the graphite and polyimide structure of the flexible substrate, elucidating the mechanism of graphite ink adhesion. The results obtained from ASTM mechanical reliability tests encompassing hardness, crease, and bending tests underscore the viability of employing Gr/PI in the manufacturing of conductive interconnects and electrodes for flexible electronic applications.

Graphical Abstract

Inspired by an improved accelerated weathering protocol to anticipate Florida exposure behavior of coatings, designated as new protocol (NP),¹ which is implemented in the ASTM D7869-13 standard, a weathering protocol is proposed to replicate the exposure in the temperate climate in Stuttgart (Germany). This protocol, designated as ZykStuttgart, has been developed by adapting the steps proposed by the NP to the climate in Stuttgart. Therefore, weather data from Homestead (Florida/USA) and Stuttgart has been analyzed and compared. Numerical simulations of water uptake and hygro-thermal stresses for model coatings were performed for varying cycle designs and using time-resolved outdoor weather data to support protocol development.

Weathering protocols, which anticipate exposure behavior of coatings in the temperate climate in Central Europe (ZykStuttgart: ZS) and Florida (new protocol: NP), were applied for accelerated testing of melamine-, silicone resin/acrylate dispersion-, and polyurethane-based coating systems and compared to natural weathering at related sites in Stuttgart (Germany) and near Homestead (Florida/USA), respectively. Color parameters and infrared spectra were measured after defined exposure times and normalized to the irradiation doses. Color changes of an industrial standard with an orange pigment (ORWET) were found to depend for both artificial and natural weathering tests predominantly on irradiation dose. This confirms that the spectral power distribution of the lamp/filter configuration proposed in NP matches sufficiently well to both the sunlight spectra in Florida and Stuttgart. For a melamine-based standard crack coat, crack initiation was found only for NP and the late stage of ZS. For all coating systems studied, characteristic band intensities of infrared spectra and/or color parameters for the two protocols and from natural weathering at the related outdoor sites were shifted along the time axis to merge to master plots. To differentiate between thermally activated, photo-initiated, and hydrolytic degradation, the shift factors were plotted versus inverse annual- or cycle-averaged temperatures including irradiation ratios and averaged humidity ratios. Despite the different reaction mechanism for the acrylic component in the silicone resin/acrylate and the polyurethane coating, a dominance of thermally activated degradation was evident for both. The melamine-based binder showed coupled degradation mechanisms (photo-induced and thermally activated complimented by moisture effects). The use of irradiation doses, cycle-, and annual-averaged temperatures together with cycle- and annual-averaged humidities for data analysis provided simple possibilities for comparison of protocols and weathering sites and a rough differentiation between degradation mechanisms.

Modified rosin resin is a widely used binder material for water-based inks, offering several benefits such as low volatile organic compound (VOC) emissions, easy cleaning, and recyclability. This review outlines the methods for preparing water-based inks using chemically modified rosin resin and highlights their excellent properties. Given the current challenges in the practical application of water-based inks, various methods are employed to enhance their adhesion, weather resistance, tensile strength, printability, and gloss. The detailed exploration of deriving water-based inks from rosin through esterification and the Diels–Alder reaction is thoroughly examined in this study. It explores the mechanisms, materials, ratios, and process conditions crucial to this preparation. By optimizing these processes, the aim is to enhance rosin utilization and propose innovative approaches for crafting high-performance water-based inks.

Graphical abstract