Journal of Coatings Technology and Research最新文献

The commonly used dispersants for graphene dispersions reduce the conductivity of the composite. In this work, a dispersant with an amphiphilic structure, CA-g-PANI, has been designed and synthesized. The dispersant grafts citric acid (CA) onto polyaniline via an amide reaction, which gives CA-g-PANI the hydrophilic groups (carboxyl groups) and the benzene ring structures that can be π–π conjugated with graphene, and it can improve the dispersion properties of graphene; CA-g-PANI contains the polyaniline structure, which is electrically conductive and enhances the electrical conductivity of graphene dispersions. The molecular structure and properties of the dispersant were systematically characterized through FTIR spectra, UV absorption spectra, and other methods. The graphene-based composites were prepared by screen printing method, and the dispersibility and resistivity of CA-g-PANI were compared with gum arabic and alkali lignin (natural dispersants). Graphene concentration reached up to 30 mg/mL in the presence of CA-g-PANI at the weight ratio of 1:0.03 (CA-g-PANI: graphene). CA-g-PANI also exhibited good performance for stabilizing graphene (stable for 6 days), with an electrical conductivity of up to 917.43 S/m. In the study, it was shown that CA-g-PANI as a graphene dispersant improved the conductivity of graphene dispersions while enhancing the dispersing properties of graphene.

In this paper, four kinds of bio-based alkyd polyols were prepared from bio-based oleic acid and coconut oleic acid as raw materials. Subsequently, UV-curable waterborne polyurethane acrylate dispersions (UV-WPUAs) were synthesized using the four bio-based alkyd polyols, respectively. Furthermore, these UV-WPUAs were employed to prepare UV-curable waterborne polyurethane acrylate coatings (UV-WPUA coatings). The study focused on comparing the effects of the four bio-based alkyd polyols on the performance of the UV-WPUAs and the resulting UV-WPUA coatings. The results showed that all the UV-WPUAs prepared from the above four bio-based alkyd polyols exhibited semitransparent, low viscosity, small particle size and high zeta potential. Additionally, the UV-WPUA-2 (alkyd polyol was prepared from oleic acid, hexahydrophthalic anhydride, neopentyl glycol and trimethylolpropane) coating exhibited excellent coating properties, such as excellent physical properties, chemical resistance and acceptable yellowing resistance. This phenomenon can be attributed to the higher crosslinking density of the UV-WPUA-2 coating, along with the lack of a benzene ring structure that is typically associated with yellowing. In conclusion, the result of this study confirms that bio-based alkyd polyols are suitable for preparing UV-curable waterborne polyurethane acrylate.

Acrylic copolymers have myriad uses in both architectural and industrial coatings. Waterborne acrylic emulsions are employed for exterior and interior architectural finishes with minimal volatile organic compound (VOC) content. However, there are still solvent-based coatings for industrial and automotive applications which result in a considerable amount of VOC. Environmental regulations to control the amount of VOC from coatings are getting stringent in most countries. Researchers across the globe are working toward reducing the VOC by either using high-solid resins or moving toward waterborne resins. The monomers employed for synthesizing acrylic resins come from petroleum, a non-renewable fossil fuel. To reduce fossil fuel consumption, efforts have been made to use greener raw materials in the polymer synthesis. Replacement of petroleum-based acrylic monomers with greener raw materials is difficult because each acrylic monomer brings a specific structure–property relationship to the polymer synthesized. Furthermore, using alternative green sources and renewable monomers brings new challenges as the synthesized resin must be compatible with solvents, additives, and pigments and meets the required properties of the acrylic coatings. In the literature, the usage of different bio-sources-based green alternatives of acrylic monomers like hydroxyl ethyl methacrylate, methyl methacrylate, butyl acrylate, methacrylic acid, and acrylic acid has been reported. As styrene is part of most acrylic resin formulations, the bio-sources of styrene and its green alternatives have also been mentioned. The alternate green monomers and their potential use in coatings’ field are also explored. A short perspective on whether green monomers and renewable sources for acrylic monomers can be commercially used to produce coatings for various applications is also discussed.

Graphical abstract

The hydrophilic nature of Algerian palygorskite (A-Pal) limits its effectiveness as a nanofiller in biopolymeric matrices due to the aggregation of its nanostructures. This study addresses this limitation by modifying the surface of (A-Pal) with triethoxyoctylsilane (TEOS) to impart hydrophobicity and enhance its compatibility with hydrophobic biopolymers. The effectiveness of this surface modification, as well as its impact on the morphology, crystal structure, surface properties, and thermal behavior of the modified palygorskite (O-Pal), was evaluated through a comparative analysis of pristine and modified samples. Fourier transform infrared spectroscopy (FTIR) and X-ray fluorescence (XRF) confirmed the successful grafting of silane onto the clay mineral surface. Additionally, X-ray diffraction (XRD) and scanning electron microscopy (SEM) demonstrated that the crystal structure of palygorskite was functionalized yet preserved following modification. Thermogravimetric analysis (TGA) indicated an enhancement in thermal stability, estimated at 14 °C, along with a 14.6% reduction in total weight loss. While BET surface analysis showed enhanced surface properties with an increase in S_BET from 121 m²/g for A-Pal to 152 m²/g for O-Pal. These findings suggest that triethoxyoctylsilane-modified palygorskite is a promising nanofiller for the development of bio-nanocomposites with improved thermal and hydrophobic properties.

Developing new recipes for waterborne polymer latex binders with improved colloidal stability and application performance is crucial for sustainable, eco-friendly textile printing processes. For this purpose, 15 waterborne poly(vinyl acetate-co-butyl acrylate) latexes were synthesized by semi-continuous emulsion polymerization using nonionic (ABIL^® B 8843, ABIL^® B 88184) and amphoteric (ABIL^® B 9950) silicone-based surfactants at five concentrations close to their critical micelle concentrations (between 0.08 and 0.24 wt.%). Other critical synthesis conditions, such as the fixed monomer ratio (85:15), initiator amount, stirring rate, total reaction time, and temperature, were kept constant to ensure reproducibility and reaction consistency in all formulations. A comprehensive characterization of the synthesized latexes was performed, colloidal stability was monitored over one year, and latexes that did not exhibit phase separation were utilized in textile pigment printing applications on both woven and knitted cotton fabrics. The AB-50-020 sample prepared using ABIL^® B 9950 at 0.20 wt.% exhibited the highest colloidal stability, characterized by a zeta potential of − 75.67 mV and the smallest particle size of 323.6 nm. Despite the high relative conversion rates (94.3–99%) of the samples obtained from ABIL^® B 8843 and ABIL^® 88184, the number of samples showing long-term stability among the formulations in these series was low, limiting their practical applications. The rubbing, washing, and color fastness, especially in formulations containing ABIL^® B 9950, highlight their suitability as sustainable alternatives for textile applications on woven and knitted cotton fabrics.

This study presents a straightforward electrodeposition strategy for fabricating a polytetrafluoroethylene (PTFE) coating with excellent stability on stainless steel substrates, aimed at inhibiting the deposition of MgO/CaCO₂ mixed fouling. By tuning the electrodeposition parameters, two hydrophobic coatings were achieved with surface roughness values of 0.148 μm (No.1 coating) and 0.056 μm (No.2 coating). The static and dynamic antifouling performance of these coatings was systematically evaluated at different temperatures (50 °C and 90 °C). The results indicate that both the surface morphology of the coatings and the temperature jointly affect the fouling suppression efficacy. No.1 coating preferentially adsorbed fouling particles due to its microprotrusion structure. Conversely, under dynamic flow conditions at 90 °C, No.2 coating exhibited a smooth surface and a significant bubble retention effect, resulting in a higher fouling inhibition rate of 82.83%. Overall, this research provides a strong foundation for future studies and practical applications of PTFE coatings in antifouling technologies.

This study assessed the safety of readily available film-forming (nitrocellulose lacquer, polyurethane, and water-based polyurethane) and penetrating finishes (linseed oil, mineral oil, and beeswax) applied to Samanea saman (Jacq.) Merr. (rain tree) wood. Residues from evaporation, potassium permanganate consumption, and UV-Vis analysis were evaluated with regards to food safety. The durability of the applied film-forming finishes was also tested following standard methods. All the film-forming finishes complied with EU migration limits under the residue on evaporation test, while none of the penetrating finishes passed. Unfinished rain tree samples displayed significantly high overall migration. Furthermore, all finishes, except PU, exhibited high levels of oxidizable components. Except for PUw and BW, all finishing materials passed the UV-Vis test. No lead, mercury, cadmium, and arsenic heavy metals were detected in the migrants from different finishes. Polyurethane consistently demonstrated superior adhesion and film hardness, thus emerging as the most promising finish for wooden tableware and kitchenware. However, to ensure food safety, further investigation to identify the migrating compounds and assess their toxicity, especially from PU, is recommended.

Photocatalytic textile based on TiO₂ has great potential in organic pollutant degradation. The key to its preparation lies in the binding of TiO₂ nanoparticles (NPs) to textile via crosslinking agent. However, in order to reach adequate coating fastness, the commonly used crosslinking agents generally suffer too much usage, which greatly reduces the photocatalytic efficiency of TiO₂. To address this problem, a novel crosslinker containing a p-phenylenediamine center and four long silanol groups is developed in this work. It not only firmly binds TiO₂ NPs to textiles with small amount, but also improves photocatalytic performance of the composites that benefit from its redox-reversible feature. Photocatalytic textiles with different weight ratios of crosslinker to TiO₂ are prepared by the spray coating method. The sample with the ratio of 1:4 shows the best photocatalytic performance and simultaneously preserves good coating fastness. The degradation efficiency for methylene blue remains over 90% after four cycles of consecutive experiments. Compared with the composites prepared using other crosslinking agents, the textile in this work shows both higher photocatalytic performance and better binding strength.

Graphical abstract

Waterborne aluminum flake composite pigments (Al@KH550@SiO₂@SA) were prepared by successively encapsulating aluminum flakes with hydrolyzed γ-aminopropyl triethoxysilane (KH550) inside nanolayer, SiO₂ intermediate inorganic nanolayer, and stearic acid (SA) outside organic layer. Hydrolyzed KH550 nanoparticles anchored at the surfaces of Al flakes via Si–O–Al bonding, SiO₂ nanoparticles anchored at the hydrolyzed KH550 nanolayers via Si–O–Si bonding, and stearic acid molecules anchored at the SiO₂ intermediate nanolayers via the interaction between carboxylic groups and surface –OH groups. The encapsulation of SiO₂ intermediate nanolayer using environmentally friendly silica sol precursor obviously improved the anticorrosion performance of resultant composite pigments. The encapsulation of stearic acid outside organic layer endowed the composite pigments with good water floating performance. The lightness, brightness, and whiteness of encapsulated aluminum flake composite pigments are comparable to those of solventborne aluminum flake pigment.