Preparation of hydrophobic nanosilica-filled polyacrylate hard coatings on plastic substrates

Colloidal silica nanoparticles synthesized from tetraethoxysilane via a sol–gel process were surface-modified first by 3-(trimethoxysilyl)propyl methacrylate, and then by trimethylethoxysilane (TMES). The former agent acts both as a coupling agent and as a C=C provider, whereas the latter agent is used to prevent particle aggregation and to increase hydrophobicity of the coating. The modified silica particles were UV-cured together with the monomer, 2-hydroxyethyl methacrylate (2-HEMA), and the crosslinking agent, dipentaerythritol hexaacrylate (DPHA), to form highly transparent hard coatings on plastic (PMMA and PET) substrates. Both differential scanning calorimetric and thermal gravimetric analyses of the hybrid materials indicated enhanced thermal stability with respect to the neat HEMA–DPHA copolymer. Furthermore, due to the incorporation of TMES, hydrophobicity of the hybrid coating increased considerably with increasing modified silica content. In the extreme case, an antiabrasive hard coating (7H on PMMA) with a water contact angle of 99° was obtained at the silica content of 15 wt%.     

Preparation and characterization of polymer/zirconia nanocomposite antistatic coatings on plastic substrates

Zirconia nanoparticles synthesized by the sol–gel method were surface modified by the coupling agent, 3-(trimethoxy silyl) propyl methacrylate (MSMA), containing C=C bonds. These particles were then UV-cured together with the hexa-functional monomer, dipentaethritol hexaacrylate (DPHA), to prepare transparent coatings that exhibited antistatic property on plastic substrates. FTIR and solid ²⁹SiNMR were used to analyze the chemical bonds in the formed particles and coatings. Dynamic light scattering measurement of the modified ZrO₂ sol indicated a relatively small particle size distribution, 1.5–20 nm, with a maximum intensity at ~5.5 nm. These particles dispersed uniformly in the organic host, poly(DPHA), as was manifested by the high resolution SEM images of the coatings. Antistatic performance of the coatings was examined based on the surface resistivity measurements. A resistivity of 7.74 × 10⁸ Ω/□ suited to common antistatic applications could be attained for coatings containing 10% inorganic component. In addition, all of the prepared coatings were very hard with pencil hardness 7H–8H, and they attached perfectly to the PMMA substrate according to the peel test.     

Preparation of zirconia loaded poly(acrylate) antistatic hard coatings on PMMA substrates

Zirconia (ZrO₂) nanoparticles were synthesized by hydrolysis and condensation of zirconium‐n‐propoxide (ZNP) in 1‐propanol at the presence of methacrylic acid (MA), serving as a chelating agent for ZNP. The formed nanoparticles were chemically modified by the UV‐curable coupling agent, 3‐(trimethoxysilyl)propyl methacrylate (MSMA). The modified particles were then crosslinked with the hexa‐functional monomer, dipentaerythritol hexaacrylate (DPHA), to produce transparent antistatic hard coatings on poly(methyl methacrylate) (PMMA) substrates. Sizes of the modified particles, as determined by the dynamic light scattering technique, fell over a small range of 2–20 nm. Chemical analyses of the particles and the coatings were performed using FTIR and/or solid ²⁹SiNMR spectroscopy. Surface resistivities of the coatings were measured, and the results indicated that with inclusion of 10 wt % modified zirconia, surface resistivity of ～10⁹ Ω/sq could be achieved, which amounted to ～6 order magnitude lower than that of the particle‐free polymeric binder. Furthermore, this antistatic coating was very hard with pencil hardness of 8–9H, and attached perfectly to the PMMA substrate according to the peel test. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42411.     

Preparation of polymer/silica composite antiglare coatings on poly(ethylene terphathalate) (PET) substrates

3-(Trimethoxysilyl) propyl methacrylate and fluoroalkylsilane modified silica particles were UV-cured with the multifunctional crosslinking agent, dipentaerythritol hexaacrylate (DPHA), to prepare antiglare (AG) coatings that exhibit high hardness. Modified silica was used to impart surface roughness whereas DPHA was used to provide hardness and adhesiveness. The formed AG coatings were characterized in terms of topological, optical, and mechanical properties. It was found that with the increase of DPHA content in the coatings, the surface roughness and haze decreased while the gloss and clarity increased. For samples containing 40 and 50 wt% DPHA, the optical properties are comparable to commercial AG products for flat panel display and touch panels. These prepared coatings also demonstrate high hardness of 5?C6H and 100% adhesion on poly(ethylene terphathalate) substrates.     

Organic base‐catalyzed sol–gel route to prepare PMMA–silica hybrid materials

A series of sol–gel‐derived organic–inorganic hybrid materials that comprise organic poly(methyl methacrylate) (PMMA) and inorganic silica (SiO₂) was successfully prepared using aniline as an organic base catalyst to catalyze the sol–gel reactions of tetraethylorthosilicate (TEOS). Aniline was adopted not only as a catalyst but also as a dispersing agent during the preparation of the hybrid materials. The as‐prepared hybrid materials were then characterized using transmission electron microscopy, SEM/energy dispersive X‐ray spectroscopy and Fourier transform infrared spectroscopy. The characteristic temperatures (including T_d and T_g) of the hybrid materials slightly exceeded those of neat PMMA, as revealed from thermogravimetric analysis and differential scanning calorimetry evaluations. Studies of the protection against corrosion demonstrated that the hybrid coatings all improved the protection performance on cold‐rolled steel coupons relative to that of neat PMMA coatings, according to measurements of electrochemical corrosion parameters. Additionally, incorporating silica particles into the polymer may effectively reduce the gas permeability of the polymer membrane. Reducing the size of silica particles (at the same silica feeding) further improved the gas barrier property. Optical clarity studies indicated that introducing silica particles into the PMMA matrix may slightly reduce the optical clarity of the films/membranes, as determined by UV‐visible transmission spectroscopy. The contact angle of H₂O of the hybrid films increased with the amount of aniline. Copyright © 2006 Society of Chemical Industry Society of Chemical Industry     

Synthesis and characterization of poly(methyl methacrylate)/polysiloxane composites and their coating properties

A series of poly(methyl methacrylate) (PMMA)/polysiloxane composites and their coatings were prepared as designed. A copolymer (PMMAVTEOS) containing methyl methacrylate (MMA) and vinyltriethoxysilane (VTEOS) was prepared by free radical polymerization and then condensed with methyl triethoxysilane (MTES) to fabricate PMMA/polysiloxane composites; their corresponding coatings were obtained via a curing process in an oven (at 75 °C). The polymers were characterized by gel permeation chromatography and Fourier transform infrared spectroscopy. The surface property, hardness, water contact angle, thermal stability, and optical property of the coatings were investigated by scanning electron microscopy, pencil hardness testing, water contact angle testing, thermogravimetric analysis, and ultraviolet–visible spectroscopy, respectively. The results showed that, after addition of MMA, the pencil hardness of the coatings was reduced from 6H to 2H and the thermal stability decreased from 365 to 314 °C. However, it increased the flexibility and adhesion properties (the water contact angle increased from 94.7° to 102.1°). The transparent PMMA/polysiloxane coatings showed excellent scratch resistance, a smooth surface, high thermal stability, and a strong adhesion property. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46358.     

短氟碳链含氟硅烷偶联剂及其疏水涂层的构建

以三氟丙基甲基环三硅氧烷(D3F)、二甲基氯硅烷、甲基二氯硅烷、乙烯基三甲氧基硅烷(VTMS)为主要原料,通过阴离子开环聚合和硅氢加成反应合成了一系列短氟碳链含氟硅烷偶联剂。载玻片表面经纳米二氧化硅溶胶涂膜和硅烷偶联剂表面修饰得到疏水涂层。探究了不同硅烷偶联剂对于涂层疏水性、附着力、硬度、透过率等性能的影响。结果表明,同类型含氟硅烷偶联剂中氟含量越大,其修饰的涂层接触角越大;相似相对分子质量及氟含量情况下,直链型含氟硅烷偶联剂修饰的涂层疏水性优于支链型修饰的涂层。经含氟硅烷偶联剂修饰的疏水涂层中,接触角最大的是由聚合度为9的支链型含氟硅烷偶联剂(DF3)修饰的涂层,可达141.6°。疏水涂层的附着力均达1级,硬度均达H,可见光透过率高于82.9%,具有良好的自清洁性能。     

Preparation of organic–inorganic hybridized dual-functional antifog/antireflection coatings on plastic substrates

Dual-functional antifog/antireflection coatings with a special bi-layer structure for plastic substrates were prepared. The superhydrophilic top layer was a crosslinked network of dipentaerythritol hexaacrylate (DPHA), hydrophilic agent (synthesized from Tween 20, isophorone diisocyanate, 2-hydroxyethyl methacrylate), and organically modified silica. The high-refractive-index bottom layer was composed of TiO₂ nanoparticles and DPHA. The two layers were chemically bonded through a UV-curing process. By tuning the thicknesses of the two layers, a series of coatings were prepared. These coatings were highly transparent and able to reduce reflectance. In addition, they adhered well to the substrate, and demonstrated superb antifogging capability on steam tests. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48822.     

Non-fluorinated,room temperature curable hydrophobic coatings by sol–gel process

Non-fluorinated hydrophobic silica surfaces were generated on soda lime glass (SLG) substrates using hexamethyldisilazane (HMDS) as a surface modifying agent. Silica coatings were fabricated by dip coating of a sol derived from base catalyzed hydrolysis and condensation of tetraethoxysilane (TEOS). Two methodologies were adopted to generate the hydrophobic surface; one where the hydrophilic silica coated surface was treated by immersion into different concentrations of alcoholic solutions of HMDS varying from 2.5 wt% to 15 wt%. In the other method, HMDS was directly added to a mixture of TEOS, water, ethanol, and ammonium hydroxide and coatings were deposited using this sol by dip coating and spray coating. Water contact angles (WCA) were measured to study the effect of HMDS treatment times and concentrations on hydrophobicity in the first case, and in the second case, WCA were measured for dip and spray coated samples. UV–visible transmission, scratch resistance, and thermal stability of the coatings were determined. The WCA increased from 66 ± 2° to 125 ± 4° after the treatment of the silica coatings with HMDS. In case of coatings generated from direct addition of HMDS to silica sol, WCA varied from 145 ± 2° to 166 ± 4° for dip and spray coated surfaces respectively. Surface morphology was studied to explain the difference in hydrophobicity of coatings generated using the two methods.     

Fabrication of transparent super-hydrophilic coatings with self-cleaning and anti-fogging properties by using dendritic nano-silica

In this paper, super-hydrophilic coatings were generated on glass substrates via dipping method using colloidal silica with different morphologies as the main raw materials. The coatings were characterized by transmission electron microscope (TEM), field emission scanning electron microscope (FE-SEM), water contact angle (WCA) analyzer, and atomic force microscope (AFM). The hardness, adhesion, self-cleaning and antifogging properties of the coatings were examined. It has been found that the hydrophilicity of the coating can be significantly improved by using dendritic silica nanoparticles, and the comprehensive performance of the coating is optimum when the branch length of dendritic silica nanoparticles is about 60 nm. The coatings show super-hydrophilicity (CA, 1.7°), and high transmittance (the maximum light transmittance of the coating on glass is increased by 2.2%). Moreover, the coating is very effective in eliminating fog and dirt. The hardness and the adhesion of the coating can be reached 9H and grade 0, respectively, indicating that the coatings have a good mechanical performance, which is essential for its application.     

Transmittance and mechanical properties of PMMA-fumed silica composites

The transmittance, flexure strength, Young's modulus, and Vickers hardness of poly(methyl methacrylate) (PMMA), filled with fumed silica, was measured. Transmittance decreased with increasing content of filler. At 2 vol % filler content, composites had a higher transmittance with a lower surface area of fumed silica (larger primary particle size) because the lower surface area filler was better dispersed. At 4 vol % filler content, composites had a higher transmittance with a higher surface area fumed silica (smaller primary particle size). Flexure strength and Young's modulus of the composites was measured using three point bending. Addition of fumed silica led to a decrease of strength. Also, addition of fumed silica led to an increase of Young's modulus and Vickers hardness. © 1992 John Wiley & Sons, Inc.     

Transparent polysilicone coatings as protecting films for gold commemorative coins

Novel transparent organic silicone resin coatings were successfully prepared through the reaction between the alkoxy groups of methyltrimethoxy‐silane (MTMS) and γ‐aminopropyltriethoxysilane (APTES) and hydroxyl groups of hydroxyl terminated silicone oil (HTSO). The influences of different monomer feed mass ratio on the coating properties were investigated via measuring the hydrophobicity and hardness of coating films. The coating films were characterized with IR, UV, TG, scanning electron microscope (SEM), and automatic contact angle meter. Some properties of coating films, such as adhesion, impact resistance, and wear‐resistance, were also evaluated. The results indicated that these coating films formed on the surfaces of gold commemorative coins possessed some good properties including high hydrophobicity, high water contact angles, high light transmittance, good heat‐resistance, adhesion, hardness, and weatherability, etc. Moreover, the uniform, clear, transparent, and dense coating films did not cover the symphony surface patterns or affect the metallic luster. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

氟硅耐候自清洁涂层的制备及在高铁动车组上应用

利用甲基丙烯酸甲酯（MMA）、甲基丙烯酸羟乙酯（HEMA）、甲基丙烯酸硬脂酸酯（SMA）、3-(丙烯酰氧基)丙基三异丙氧基硅烷（AC-76）和2-(全氟辛基)乙基甲基丙烯酸酯（FOEMA）合成一系列不同单体比例的聚合物（P1~P5），并用于构建耐候自清洁涂层。利用FTIR、1HNMR对聚合物结构进行表征，采用紫外-可见分光光度计及接触角测量仪测试了FOEMA和SMA质量分数涂层的透光率及疏水性的影响，当SMA质量分数为10%，FOEMA质量分数为15%（以反应体系总质量计，下同）时制备的涂层P3具有最大的透光率和水接触角，分别为98.6%和105.3°；人工加速老化实验结果表明，涂层P3具有极佳的耐候性，加速老化5000 h后，涂层的保光率及疏水性变化很小；液滴滑落及涂鸦实验结果表明，涂层P3具有优异的抗污及自清洁效果；摩擦实验结果表明，涂层P3在900 g压力下摩擦100次后其接触角仍大于95°，说明其具有优异的机械稳定性。最后，将该涂层喷涂到高铁动车组上，该涂层对动车组外车身实际污染物具有明显的自清洁效果。     

Fabrication and properties of polysilsesquioxane-based trilayer core–shell structure latex coatings with fluorinated polyacrylate and silica nanocomposite as the shell layer

Polysilsesquioxanes (PSQ)-based core–shell fluorinated polyacrylate/silica hybrid latex coatings were synthesized with PSQ latex particles as the seeds, and methyl methacrylate, butyl acrylate, 3-(trimethoxysilyl) propyl methacrylate (MPS)-modified SiO₂ nanoparticles (NPs), 1H,1H,2H,2H-perfluorooctyl methacrylate (PFOMA) as the shell monomers by emulsifier-free miniemulsion polymerization. The results of Fourier transform IR spectroscopy, transmission electron microscopy, and dynamic light scattering suggested the obtained hybrid particles emerged with trilayer core–shell pattern. Contact angle analysis, x-ray photoelectron spectroscopy, and atom force microscopy results indicated that the hybrid film containing SiO₂ NPs showed higher hydrophobicity, lower surface free energy and water absorption, in comparison with the control system (without SiO₂ NPs). Compared with the control system, the hybrid latex film containing SiO₂ NPs in the fluorinated polyacrylate shell layer showed the higher content of fluorine atoms and a rougher morphology on the film surface. Additionally, thermogravimetric analysis demonstrated the enhanced thermostability of PSQ-based nanosilica composite fluorinated polyacrylate latex film.     

Preparation of super‐hydrophobic film with fluorinated‐copolymer

Organic superhydrophobic films were prepared by utilizing TA‐N fluoroalkylate (TAN) and methyl methacrylate (MMA) copolymer as water‐repellent materials and inorganic silica powder as surface roughness material has been developed. Coating solutions prepared by adding silica powders into copolymer solution directly (one‐step method) and by adding silica powders into monomers and allowing them to react (two‐step method). The results showed that contact angles of the films prepared by one‐step method (37.6 wt % of silica powders in the coating solution) were greater than 150°, but the transmittance of the film at visible light was only 30%. On the other hand, the contact angle of films prepared by two‐step method (20 wt % of silica powders in the coating solution) was greater than 160° and the transmittance of the film was greater than 90%. The contact angle of the film prepared by poly(octyl acrylate), POA, was 32.1°, but while introducing silica powder into the system, the contact angle of the film was reduced to be smaller than 5°. Thus, superhydrophobic and superhydrophilic films can be obtained by introducing a roughening material on the hydrophobic surface and the hydrophilic surface, respectively. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1646–1653, 2007     

Synthesis and characterization of organic-inorganic hybrid thin films from poly(acrylic) and monodispersed colloidal silica

Hybrid thin films containing nano-sized inorganic domain were synthesized from poly(acrylic) and monodispersed colloidal silica with coupling agent. The 3-(trimethoxysilyl)propyl methacrylate (MSMA) was bonded with colloidal silica first, and then polymerized with acrylic monomer to form a precursor solution. Then, the precursor was spin coated and cured to form the hybrid films. The silica content in the hybrid thin films was varied from 0 to 50 wt%. The experimental results showed that the coverage area of silica particle by the MSMA decreased with increasing silica content and resulted in the aggregation of silica particle in the hybrid films. Thus, the silica domain in the hybrid films was varied from 20 to 35 nm by the different mole ratios of MSMA to silica. The results of scanning electron microscope, transmission electron microscope, and elemental analysis support the above results. The prepared hybrid films from the crosslinked acrylic polymer moiety showed much better film uniformity, thermal stability and mechanical properties than the poly(methyl methacrylate) (PMMA) based hybrid materials. Large pin-holes were found in the PMMA-silica hybrid films probably due to the significant difference on thermal properties between the two moieties or the evaporation of solvent. The refractive index decreased linearly with increasing the silica fraction in the hybrid films. Excellent optical transparence was obtained in the prepared hybrid films. These results show that the hybrid thin films have potential applications as passive films for optical devices.     

Fabrication of durable hydrophobic cellulose surface from silane‐functionalized silica hydrosol via electrochemically assisted deposition

Durable excellent hydrophobic surface on cellulose substrate was fabricated from the silica hydrosol functionalized with silane chemicals by a facile electrochemically assisted deposition technique. The silica hydrosol was synthesized using tetraethoxysilane (TEOS) as the precursor and sodium dodecylbenzene (SDBS) as the emulsifier under acidic conditions. The hydrophobic silane modifiers including octyltriethoxysiliane (OTES), dodecyltriethoxysiliane (DTES) and isooctyltriethoxysiliane (iso‐OTES) and the silane‐coupling agent γ‐mercaptopropyltriethoxysilane (MPTES) were used to dope the silica hydrosol for preparing durable hydrophobic cellulose surface. The cellulose surface modified with silane modifier iso‐OTES exhibited the best hydrophobicity with water contact angle of 162.3 ± 0.5° due to its non‐polar and hydrolytically stable of ? Si(C₈H₁₇) groups. The addition of silane‐coupling agent MPTES containing the ? SH group led to good durability of hydrophobicity with water contact angle of 130.0 ± 1.2° after 20 washing times. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42733.     

Preparation of UV-cured spironaphthooxazine/silica/polyacrylate photochromic hard coatings on plastic substrates

Hard coatings exhibiting photochromic properties were prepared by UV-curing of formulations that incorporated surface-modified silica nanoparticles, hexa-functional curing agent, and organic dye (spironaphthooxazine) on poly(methyl methacrylate) (PMMA) substrates. Spectroscopic studies of the coatings indicated effective photochromic activities over the visible range in response to UV irradiation (365 nm). The color density and bleaching performance were found to depend on the silica and dye contents in the coatings; generally, increasing either quantity could increase the color density and raise the initial bleaching rate, and yet it took a longer time to completely bleach the coatings. Furthermore, the coatings were very hard (8H), attached perfectly (5B) on the substrate, and were much more wear-resistant than pure PMMA against the CS-10 abradant.     

Physical properties and crystallization behavior of poly(lactide)/poly(methyl methacrylate)/silica composites

Poly(lactide)/poly(methyl methacrylate)/silica (PLA/PMMA/SiO₂) composites were fabricated using a twin‐screw extruder. Nanosilica particles were incorporated to improve the toughness of the brittle PLA, and a chain extender reagent (Joncryl ADR 4368S) was used to reduce the hydrolysis of the PLA during fabrication. Highly transparent PLA and PMMA were designated to blend to obtain the miscible and transparent blends. To estimate the performance of the PLA/PMMA/SiO₂ composites, a series of measurements was conducted, including tensile and Izod impact tests, light transmission and haze measurements, thermomechanical analysis, and isothermal crystallization behavior determination. A chain extender increases the ultimate tensile strength of the PLA/PMMA/SiO₂ composites by ～43%, and both a chain extender and nanosilica particles increase Young's modulus and Izod impact strength of the composites. Including 0.5 wt % nanosilica particles increase the elongation at break and Izod impact strength by ～287 and 163%, respectively, compared with those of the neat PLA. On account of the mechanical performances, the optimal blending ratio may be between PLA/PMMA/SiO₂ (90/10) and PLA/PMMA/SiO₂ (80/20). The total light transmittance of the PLA/PMMA/SiO₂ composites reaches as high as 91%, indicating a high miscible PLA/PMMA blend. The haze value of the PLA/PMMA/SiO₂ composites is less than 35%. Incorporating nanosilica particles can increase the crystallization sites and crystallinities of the PLA/PMMA/SiO₂ composites with a simultaneous decrease of the spherulite dimension. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42378.     

Electrochemical investigations on the corrosion protection effect of poly(vinyl carbazole)‐silica hybrid sol–gel materials

A series of sol–gel derived organic–inorganic hybrid coatings consisting of organic poly (vinyl carbazole) (PVK) and inorganic silica (SiO₂), with 3‐(trimethoxysilyl)propyl methacrylate (MSMA) as coupling agent, were successfully synthesized. First of all, vinyl carbazole (VCz) monomers are copolymerized with MSMA by performing free‐radical polymerization reactions with AIBN as initiator. Subsequently, as‐prepared copolymer (i.e., sol–gel precursor) was further reacted with various feeding content of tetraethyl orthosilicate (TEOS) through organic acid (CSA)‐catalyzed sol–gel reaction to form a series of PVK‐silica hybrid (PSH) sol–gel materials. The as‐synthesized hybrid materials were subsequently characterized by Fourier‐Transformation infrared (FTIR) spectroscopy and solid‐state ²⁹Si NMR. It should be noted that the PVK‐SiO₂ hybrid (PSH) coating on cold‐rolled steel (CRS) electrode with low silica loading (e.g., 10 phr) was found to be superior in anticorrosion property over those of neat PVK based on a series of electrochemical measurements such as corrosion potential, polarization resistance, corrosion current, and electrochemical impedance spectroscopy in 3.5 wt% NaCl electrolyte. The better anticorrosion performance of PSH coatings as compared to that of neat polymer may probably be attributed to the stronger adhesion strength of PSH coatings on CRS electrode, which was further evidenced by Scotch tape test evaluation. Increase of adhesion strength of PSH coatings on CRS electrode may be associated with the formation of Fe–O–Si covalent bonds at the interface of PSH coating and CRS electrode based on the FTIR–RAS (reflection absorption spectroscopy) studies. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers