Anti-smudge Coatings Research Articles

Nano silicone oil pools with wear-responsive secretion for enhancing self-healing in hard anti-smudge coatings

Nano silicone oil pools with wear-responsive secretion for enhancing self-healing in hard anti-smudge coatings

Waterborne Liquid-like Coatings with High Transparency, Superior Scratch Resistance, and Antismudge Properties.

The aqueous formulation of antismudge coatings is a crucial step for environmental protection and pollution reduction. However, the inferior mechanical durability of waterborne antismudge coatings poses challenges for their practical application. Herein, we developed a fully waterborne antismudge coating with excellent scratch resistance by preparing hyperbranched amine-rich polysiloxane (HySPx) for antismudge ability and epoxy-rich zirconium-based aqueous solution (ZAS) for mechanical performance. The former is obtained by combining SPx, polydimethylsiloxane modified by 3-isocyanatopropyltriethoxysilane (IPTS), with 3-aminopropyltriethoxysilane (KH550), and the latter is synthesized using zirconium propoxide solution (TPOZ) with 3-glycidyloxypropyltrimethoxysilane (KH560). This report investigates the effects of the chain length and content of SPx on the performance of the coating. The results indicate that the coating exhibits optimal comprehensive performance when the molecular weight of polydimethylsiloxane is 4.5 kDa, and the mass fraction of SPx in HySPx is 1.5%. The coating possesses high transparency similar to glass, good adhesion (≈3 MPa) to various substrates, high hardness (8H), flexibility (2.5 mm bending radius), and exceptional antismudge property. More importantly, the coating can still maintain excellent antismudge property even after enduring 400 cycles of abrasion with steel wool. Furthermore, the rapid enrichment of polydimethylsiloxane on the coating surface endows the coating with excellent lubrication ability, allowing most common liquid stains to slide off the coating surface. Moreover, the rewritability of the coating remains stable even after writing traces that have persisted on its surface for several weeks. This coating is anticipated to be utilized for protecting foldable electronic screens, vehicles, and other fields.

Solvent-free polyurethane coatings based on an in-situ curing strategy at room temperature with self-cleaning, anti-corrosion and anti-graffiti properties

Anti-smudge coatings have attracted extensive attention in recent years owing to their hydrophobic, self-cleaning, anti-graffiti properties and so on. However, most of the anti-smudge coatings are solvent-based and cured at high temperature or using special curing equipment, which negatively impacts the environment and limits their large-scale application in daily life. Herein, we report a solvent-free anti-smudge coating with potential for large-scale and green manufacturing. In detail, polydimethylsiloxane (PDMS) was used as the hydrophobic component, (3-aminopropyl)triethoxysilane (APTES) and 3-glycidoxypropyltrimethoxysilane (GPTMS) were used as the cross-linking agent, and a solvent-free polyurethane (SFPU) anti-smudge coating was in-situ constructed at room temperature for 24 h without any curing equipment. Due to the enrichment of PDMS chains on the surface and the dense cross-linked network of the coating, the as-prepared coating not only exhibited a high contact angle for water (99.3 ± 1.5°) and diiodomethane (69.5 ± 0.9°), but also excellent anti-smudge to contaminants, with both water and oily liquids were easy to slide off the surface of the coating without leaving any traces. Even after writing with an oil-based marker, the ink on the coated surface could be easily wiped off. Further study reveals that the coating surface maintained its original liquid repellency and stain resistance even after 10 d immersion in a 10 wt% NaCl solution, showing durable anti-corrosion properties. In addition, pigments did not affect the anti-graffiti performance of the coating, providing a multi-color scheme for practical application. This convenient, low-energy, environmentally friendly anti-smudge coating has great potential for widespread application in industry and daily life.

Fabrication of photocurable liquid-like easy-cleaning coatings based on a polydimethylsiloxane-modified silicone resin

Smooth liquid-like surfaces formed by flexible polymer brushes or alkyl monolayers exhibit great potential as easy-cleaning coatings. However, solvent-free, and easily curable coating formulations that are environmentally-friendly, omniphobic, low-cost, and durable liquid-like surfaces are still lacking. This paper reports the synthesis of a polydimethylsiloxane (PDMS) modified silicone resin additive for the preparation of easy-cleaning photocurable liquid-like coatings. A highly-branched silicone resin (MAP) containing PDMS and acrylate groups was synthesized by acid hydrolysis condensation and then added to polyurethane acrylate (PUA) to prepare UV-curable coatings. The coatings with only 1 wt% MAP addition exhibited hydrophobicity and oleophobicity, as well as dust and graffiti resistance due to their low surface tension and the self-migration of PDMS chains in the MAP resin. Meanwhile, the coating surface was smooth, highly transparent, and showed excellent abrasion resistance because the highly-branched structure of MAP was conjugated with many acrylate groups. This enhanced the compatibility of the MAP resin with PUA and strengthened the cross-link density of the coating. Consequently, the photocurable easy-cleaning coating provides a facile strategy for preparing environmentally friendly and mechanically robust anti-smudge coatings.

Facile fabricated transparent anti-smudge coating with high hardness and excellent flexibility from MTQ and branched silicone resins

The demand for high-transparent functional coatings with glass-like hardness, polymer-like flexibility, and anti-smudge properties has increased significantly, especially for foldable touchscreens. However, it is challenging to achieve all the required properties in a coating because the realization of these properties may conflict with each other. In this study, we present a facile method for preparing a special organic-inorganic hybrid coating by utilizing epoxy MTQ silicone resins and amine-terminated hyperbranched polysiloxane (HPSi). The chemical structure of the MTQ resin was fine-tuned to obtain the optimal M/T/Q ratio, and a novel HPSi with rich crosslinking sites and excellent flexibility was prepared as the curing agent. The resulting hybrid network imparted the coating with exceptional hardness (pencil hardness, 7–9H) and excellent flexibility (<2 mm bend diameter). In addition, by modifying the MTQ resin with fluorosilane, the surface energy of the coating was reduced to 14.8 ± 0.4 mJ/m2 and its anti-smudge and self-cleaning properties were improved without sacrificing the transparency of the coating (99.4 % at 550 nm). Notablely, even after 1000 cycles of steel wool abrasion, these coatings still maintain their outstanding performance. This study provides a promising strategy for the development of hard, flexible, and anti-smudge coatings suitable for foldable displays and other related fields.

Fabrication of UV-curable waterborne polyurethane coatings with self-cleaning, anti-graffiti performance, and corrosion resistance

A novel UV-curable anti-smudge coating based on waterborne polyurethane (WPU) was constructed by using polydimethylsiloxane (PDMS) as hydrophobic material and pentaerythritol triacrylate (PETA) as UV-curable cross-linking agent. At the same time, the effect of PDMS loading and the cross-linking density on the transparency, hydrophobicity, as well as graffiti resistance of the coating, were investigated. Due to the high cross-linking density, the obtained coating possessed desirable optical transparency. The synergistic effect of hydrophobic side chains and dense cross-linking imparts the coating favorable repellency to pollutant liquids such as water, coffee, muddy water, ink, hexadecane, ethanol, fingerprint liquid and others. The coating showed good anti-graffiti properties on a variety of substrates, including glass, tinplate, ceramics, wood, and paper sheet. In addition, aside from protecting the substrate against strong acid, alkali, and salt solutions, the coatings remained stain resistant despite being folded and curled. This study provides a new strategy for the design of WPU UV-curable anti-smudge coatings.

Preparation of epoxy-based silicone prepolymers with applications in UV-curable coatings

PurposeThis paper aims to investigate the effects on coatings performance in the epoxy silicone resin system owing to the existence of the different chain length of open-chain epoxy monomer. In this paper, [4-Methylphenyl-(4–(2-methylpropyl) phenyl)]iodonium as photoinitiator was added into epoxy silicone resin by ultraviolet (UV)-cured polymerization to investigate the effects on coatings performance owing to the existence of the different chain length of open-chain epoxy monomer.Design/methodology/approachA simple hydrosilylation reaction was used to synthesize epoxy-based silicone prepolymers by using hydrogen-terminated polydimethylsiloxane, 1,2-epoxy-5-hexene, 1,2-epoxy-7-octene and 1,2-epoxy-9-decene as precursors.FindingsThe results revealed that the glass transition temperatures (Tg) and hydrophobicity increased with the chain length of open-chain epoxy monomer in the UV curable epoxy-based silicone coatings, and these films had excellent heat resistance, hydrophobicity, antigraffiti and ink removal properties.Research limitations/implicationsThe cationic photocuring systems are not susceptible to the effect of oxygen inhibition. However, the limitation of cationic light curing process is that it requires a long curing time.Originality/valueThe coatings prepared via the UV curing approach can provide superior antismudge effects, and thus they are promising candidates for use in various industries, especially in fields such as antismudge coatings and antigraffiti coatings.

Inorganic–Organic Silica/PDMS Nanocomposite Antiadhesive Coating with Ultrahigh Hardness and Thermal Stability

Antiadhesive surfaces have been gaining continuous attention, because of the scientific and industrial significance. Slippery surfaces and antismudge coatings with antiadhesive behavior have been readily designed and prepared. However, improving robustness of the surfaces, especially the simultaneous demonstration of features of high hardness, excellent adhesion to different substrates, and high thermal stability, is constantly challenging. Herein, we present a silica/polydimethylsiloxane (PDMS) nanocomposite coating (SPNC), wherein silica acts as a consecutive phase and nanophased PDMS is covalently embedded. The nanoconfined PDMS phase exhibits enhanced thermal stability and endows SPNC with slippery behavior; meanwhile, enrichment of PDMS on the surface renders a gradient composition of the coating. Accordingly, the inorganic-organic SPNC simultaneously displays a high nanoindentation hardness of 3.07 GPa and a pencil hardness over 9H, outstanding thermal stability of the slippery performance up to 400 °C, and excellent adhesion strength to different substrates. Additionally, SPNC exhibits high optical transparency, flexibility, resistance to bacterial clone, and chemical corrosion. With the scalable fabrication process, it can be envisioned that the antiadhesive coating with unprecedented comprehensive merits in this work has significant potentials for large-area applications, especially under severe service environments.

Bio-Based Waterborne Polyurethane Coatings with High Transparency, Antismudge and Anticorrosive Properties.

Green and environment-friendly preparation are of the utmost relevance to the development of transparent antismudge coatings. To prepare a waterborne polyurethane (WPU) coating with antismudge property, it is challenging to balance the stability of dispersion and the antismudge property of coating. Herein, we prepare a transparent bio-based WPU coating grafted with a minor proportion of poly(dimethylsiloxane) (WPU-g-PDMS) using renewable castor oil, monocarbinol-terminated PDMS, hexamethylene diisocyanate trimer, and 2,2-bis(hydroxymethyl)propionic acid as raw materials. Effects of the dosage of monocarbinol-terminated PDMS, the curing temperature, and the curing time on the antismudge performance were studied. Results showed that rigorous stirring (3000 rpm) is necessary to obtain a stable WPU-g-PDMS dispersion with a storage time longer than 6 months. A high curing temperature (>160 °C) and a period of curing time (>1 h) are indispensable to obtain the excellent antismudge property because they would facilitate the grafted low-surface-tension PDMS chains to migrate from the interior to the coating surface. The facts that simulated contaminated liquids such as water, HCl solution, NaOH solution, artificial blood, and tissue fluid could slide off easily and cleanly, and marker ink lined on the coating surface could shrink, indicated that the WPU-g-PDMS coating has good antismudge properties, which could be self-compensated shortly after deterioration. Due to the high cross-linking degree caused by multifunctional polyol and isocyanate, the WPU-g-PDMS coating has high hardness and good anticorrosive performance. The antismudge functionalization and waterborne technology of bio-based polyurethane coatings proposed in this work could be a promising contribution to the green and sustainable development of functional coatings. This kind of WPU-g-PDMS coating is expected to protect and decorate electronic screens, vehicles, and buildings, especially endoscopes.

A substrate-independent transparent UV-curable coating with excellent anti-smudge performance

Anti-smudge coatings are recognized as being strongly desirable because they are able to repel numerous contaminants and maintain surfaces spotless without cleaning. However, a simple preparation process suitable for various substrates has rarely been reported. Herein, a novel UV-curable transparent anti-smudge coating with adjustable wetting properties was prepared. Introducing polydimethylsiloxane (PDMS) as a low surface energy additive and trimethylolpropane triacrylate (TMPTA) as a crosslinking agent to a polyurethane acrylate (PUA) skeleton results in a coating that shows dynamic dewetting performance as well as extensive repellency to water- and oil-borne contaminants, including graffiti, ink, cooking oil, and salt solution. Additionally, owing to the advantages of a non-thermal and rapid UV-curing strategy, the obtained coating can be applied to a variety of substrates including heat-sensitive materials. This study provides unique insights into the design and fabrication of functional coatings aimed at dewetting surfaces, membrane separation, and petroleum and biomedical engineering applications.

Anti-smudge and self-cleaning characteristics of waterborne polyurethane coating and its construction

A novel anti-smudge coating, based on waterborne polyurethane (WPU), Polydimethylsiloxane (PDMS) and Hexamethoxymethylmelamine (HMMM) was constructed. Specifically, hydroxyl capped WPU emulsions grafted with PDMS (WPU-g-PDMSX) were prepared firstly, then the Hexamethoxymethylmelamine (HMMM) was used as the crosslinking agent to block the polar hydrophilic hydroxyl groups and the carboxyl groups in WPU-g-PDMSX and increase the cross-linking density of the coating. Oily markers, water, hexadecane, fingerprint liquid, and common liquids in life (milk, coffee, ink and cooking oil) were utilized to demonstrate the anti-graffiti and self-cleaning characteristics of coatings. Aside from having great transparency and exceptional resistance to liquid corrosion, the coating still retains its anti-smudge capabilities even when bent or impacted, and they also exhibit 5B adhesion and 5H pencil hardness. This work provides novel idea and strategy for the preparation of WPU anti-smudge coatings.

Preparation of multifunctional silicone acrylate prepolymers with anti-oxygen inhibition ability for application in UV-curable anti-smudge coatings

UV curing technology is a new green technology developed in the 21st century, and has been widely used in daily life and industrial production. However, a major drawback encountered with UV curing is oxygen inhibition, especially in free radical photopolymerization. As reported herein, three multifunctional silicone acrylate prepolymers were obtained via the one-step hydrosilylation of dipentaerythritol hexaacrylate (DPHA) and hydride-terminated polydimethylsiloxane (H-PDMS). These prepolymers contain five acrylate groups at each end of the polysiloxane chain, and also has a high viscosity, all of which contribute to overcome oxygen inhibition, and thus they have efficient anti-oxygen inhibition abilities. After the addition of a few photoinitiators, each of the prepolymers could be rapidly cured in air to yield a transparent film. The transparency of these cured films is over 95% on the surface of an underlying polyethylene terephthalate (PET) substrate. They remain stable at temperatures reaching up to 352.2 to 364.8 °C, thus demonstrating that they have excellent heat resistance. Water droplets exhibit water contact angles between 103° and 105° on these films, and surface energies of the cured films are from 24.58 to 20.69 mN/m. Finally, the coatings have good anti-smudge and anti-fingerprint properties, and the overall results show that these films have potential applications as UV-curable anti-smudge coatings.

One-step synthesis of novel multifunctional silicone acrylate prepolymers for use in UV-curable coatings

As reported herein, three multifunctional silicone acrylate prepolymers were obtained via the one-step hydrosilylation of pentaerythritol tetraacrylate (PETTA) and hydride-terminated polydimethylsiloxane (H-PDMS). The structures of these prepolymers were subsequently characterized by FT-IR and 1H NMR spectroscopy techniques, which confirmed the successful synthesis of the target products. These prepolymers contain three acrylate groups at each end of the polysiloxane chain, which can participate in the UV curing process, and thus they have high UV curing activities. After the addition of a little photoinitiator, each of the prepolymers could be rapidly cured to yield a transparent film. The transparency of these cured films is over 95% on the surface of an underlying polyethylene terephthalate (PET) substrate. Water droplets exhibit water contact angles between 100° and 105° on this film, these films remain stable at temperatures reaching up to 356.0 to 386.8 °C, thus demonstrating that these films are hydrophobic and have excellent heat resistance. Finally, the coatings have good anti-smudge properties, and the overall results show that these films have potential applications as UV-curable anti-smudge coatings.

High-Performance Bio-Based Polyurethane Antismudge Coatings Using Castor Oil-Based Hyperbranched Polyol as Superior Cross-Linkers

High-Performance Bio-Based Polyurethane Antismudge Coatings Using Castor Oil-Based Hyperbranched Polyol as Superior Cross-Linkers

Are telechelic polysiloxanes better than hemi-telechelic for self-cleaning applications?

HypothesisPolysiloxanes are becoming new trend in self-cleaning (oil- and water‐repellent) applications due to their low-cost and environmentally friendly nature. Lower phase separation of polysiloxanes in coating matrix is critical to obtain excellent self-cleaning properties. We hypothesize that telechelic polysiloxanes can bind to coating matrix at both ends and thus will suppress phase separation of polysiloxane as compared to hemi-telechelic analog and thus will offer excellent self-cleaning properties. ExperimentEight PDMS additives were prepared via the free-radical polymerization of telechelic and hemi-telechelic methacryloxypropyl-based PDMS precursors with methylmethacrylate (MMA) and glycidylmethacrylate (GMA). The compositions of the prepared polysiloxane additives were optimized to obtain excellent self-cleaning performance. FindingsOur breakthrough development confirms that telechelic polysiloxanes (PDMS-T) incorporated into epoxy-based anti-smudge coatings outperform hemi-telechelic polysiloxanes (PDMS-HT) by offering excellent repellency against difficult to repel liquids. These breakthrough findings will vertically advance Science and innovations in the self-cleaning field by offering robust guidelines for choosing suitable polysiloxane for self-cleaning applications.

Fabrication of ultra-smooth hybrid thin coatings towards robust, highly transparent, liquid-repellent and antismudge coatings

Liquid-repellent and anti-smudge coatings have a wide range of applications on the surface of materials. In this work, a novel liquid-repellent anti-smudge hybrid coating was in situ fabricated by using tetraethyl orthosilicate (TEOS) and dimethoxydimethylsilane (DMDEOS) under acid catalysis. The resulting coatings had a high transmittance of 3–4% higher than that of blank glass. The superior smoothness and high mobility of generated poly(dimethyl siloxane) (PDMS) chains on the surface resulted in low sliding angles of 4.5° (water) and 2.8° (n-hexadecane), and a high water sliding velocity of 15.6 cm s−1 at a tilting angle of 70°. In addition, the hybrid coatings could repel both ink and dust contaminations and hinder bacteria adhesion. What’s more, the anti-smudge coatings demonstrated excellent durability and mechanical properties of 8H pencil hardness and 5A adhesion grade. Thus, a new perspective is provided for the preparation of anti-smudge coatings. The simple preparation method would bring a breakthrough in the development and application of anti-smudge materials.

Robust Hybrid Omniphobic Surface for Stain Resistance.

Inspired by natural living surfaces, researchers have developed many excellent anti-smudge coatings, but there remain some critical challenges such as complex or expensive fabrications, poor long-term stability, non-transparency, etc., which may limit their large-area application. In this work, we designed a robust and transparent omniphobic coating with a one-step dip coating method. The perfluoropolyether chains were grafted on a smooth glass surface, and the coating surface not only presented good liquid repellency and stain resistance but also owned excellent mechanical wear resistance. The stain resistance property and wettability have barely changed after hundreds of thousands of friction cycles in air or even in an organic solvent surrounding. The robust hybrid coating possesses simple preparation, an excellent property, and durability, which may bring a widespread interest in the engineering application field.

High modulus, fluorine-free self-healing anti-smudge coatings

Reported herein is a simple strategy for the fabrication of phenolic polyurethane coatings with self-healing and anti-smudge properties as well as good mechanical strength and optical clarity. Polydimethylsiloxane (PDMS) is incorporated to impart anti-smudge performance into urethane matrix comprised of biobased propyl gallate, hexamethylene diisocyanate trimer, and polytetrahydrofuran prepolymer. Propyl gallate is used as a reversible crosslinker to impart the self-healing properties to the coating. The reaction products were confirmed by Fourier transform infrared spectroscopic studies. Optical microscopic analysis was used to observe the self-healing behavior of polymer films. The contact angle and sliding angle tests were used to evaluate the anti-smudge ability of these polymers. Tensile test, hardness, and abrasion test were used to validate the mechanical properties of the coatings. The obtained coatings showed excellent anti-smudge properties as evident from their water, oil, ink, and hexadecane repellencies. Also, these coatings showed excellent optical clarity approach 100% transmittance. Furthermore, these coatings exhibit promising self-healing properties, which recover from 40 μm cuts in ∼10 min at 120 ℃ and in 1 h at 80 ℃. As this approach offers a simple route towards multi-functional coatings, therefore, real-world applications are anticipated for the coatings reported in this study.

Transparent Omniphobic Coating with Glass-Like Wear Resistance and Polymer-Like Bendability.

Transparent omniphobic or anti-smudge coatings with glass-like wear resistance and polymer-like bendability have many potential applications but there are no reports of such materials. We Report herein a molecular composite possessing these properties. The composite is prepared via the photo-initiated ring-opening polymerization of the epoxide rings of glycidyloxypropyl polyhedral silsesquioxane (GPOSS). While the desired hardness is provided by the silica core, the flexibility is imparted by the glycidyloxypropyl network. Oil and water repellency is achieved without adversely affecting the other properties by incorporating a low-surface-tension liquid lubricant poly(dimethyl siloxane). On the final coating, various organic solvents and water readily and cleanly glide, while complex fluids, such as ink and paint facilely contract. These properties are retained after an initially flat coating sample is rolled into a U-shape 500 times or is abraded with steel wool.

Robust Hyperbranched Polyester-Based Anti-Smudge Coatings for Self-Cleaning, Anti-Graffiti, and Chemical Shielding.

In this work, a novel anti-smudge coating system was developed by using hydroxyl-terminated hyperbranched polyester as a coating precursor, mono-hydroxyl-terminated poly(dimethylsiloxane) (PDMS) as an anti-smudge agent, and hexamethylene diisocyanate trimer as a curing agent. The resultant coatings with 0.5 wt % PDMS content incorporated are highly transparent and liquid repellent. They exhibit striking repellency against various liquids and display remarkable self-cleaning performance. Water, hexadecane, salt solution, strong alkali solution, strong acid solution, pump oil, and crude oil could slide off the coated surface without leaving any traces, and the dirt on the coated surface could be readily removed by water or oil. Besides, these coatings show potential application for anti-fingerprint and anti-graffiti due to the exceptional repellency of coated surface against artificial fingerprint liquid, oil-based ink, paint, and water-based smudge. Furthermore, they also possess superb chemical shielding ability and thus endow substrates with remarkable protection against exposure to harsh chemical conditions. Moreover, these coatings are mechanically robust against extensive abrasion, impact, and bending without compromising anti-smudge properties, and they also exhibit excellent adhesion to various substrates. Therefore, these newly developed coatings have tremendous potential for widespread applications.