Hydrophobic Antireflective Silica Coatings via Sol-gel Process (original) (raw)
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Surface and Coatings Technology, 2012
This paper reports the synthesis of hydrophobic and antireflective coatings by sol-gel process at room temperature (25°C), using tetraethylorthosilicate (TEOS) as a precursor and methyltriethoxysilane (MTES), phenyltriethoxysilane (PTES), vinyltriethoxysilane (VTES), and octyltriethoxysilane (OTES) as surface modifying agents. The silica sol was prepared by keeping the molar ratio of TEOS:RTES at 1:1, in acidic conditions with ethanol and 0.1 M HCl. All hybrid systems were enriched with titanium(IV) isopropoxide as the cross-linking agent. It was observed that the obtained silica films become hydrophobic with the introduction of the hydrophobic organic group. The higher value of static water contact angle (107 ± 3°) was obtained for the silica film prepared with TEOS + OTES. Under optimal synthesis condition, we obtained antireflection coatings, exhibiting a low reflection in the visible range.
Sol-gel Derived Optical Coating with Controlled Parameters
The optical properties and structure of antireflective coatings (AR) deposited from hydrolysed TEOS sol were characterized in detail in this study. The influence of different parameters on the formation of colloidal silica antireflective coatings by dip-coating technique has been investigated. For the characterization of colloidal silica films the UV-visible spectroscopy, laser ellipsometry and atomic force microscopy were used. Using optimal sol-gel processing conditions (dipping rate – 40 mm/min, coating time – 20 s, and temperature – 20 °C) the colloidal silica coatings were obtained and characterized in comparison with non-coated glass substrate. The reflectance of AR coatings increases with increasing the temperature of sol-gel processing. The Nd:YAG laser damage threshold of AR coating exceeded 15.22 J/cm 2 at 1064 nm and 26.82 J/cm 2 at 355 nm.
Study on low-refractive-index sol-gel SiO2 antireflective coatings
Chinese Optics Letters, 2016
A study on low-refractive-index SiO 2 antireflective (AR) coatings by a sol-gel method is reported. Variations in the properties of the coatings are related to the molar ratios of ammonia to deionized water being changed in the process of preparing the sols. From the performance test results, the optimal ratio of the reactants necessary to prepare low-refractive-index SiO 2 AR coatings is determined. Of all the SiO 2 AR coatings, the lowest recorded refractive index is 1.16 at a wavelength of 700 nm. The largest water contact angle is 121.2°, and the peak transmittance is 99.95% at a wavelength of 908 nm. Furthermore, the sol used to deposit the film with the lowest refractive index is stable because of the narrow size distribution of its constituent particles.
Optical characterization of antireflective sol-gel coatings fabricated using dip coating method
Laser-Induced Damage in Optical Materials: 2006, 2006
In recent years, there has been a growing interest in further development of sol-gel method which can produce ceramics and glasses using chemical precursors at relative low-temperatures. The applications for sol-gel derived products are numerous. Physics continues an ongoing research effort on the synthesis, deposition and characterization of porous solgel. Our target is highly optically resistant anti-reflective (AR) coatings for general optics and nonlinear optical crystals. In order to produce AR coatings a silica (SiO 2 ) sol-gel has been dip coated on the set of fused silica substrates. The optical properties and structure of AR-coatings deposited from hydrolysed tetraethylorthosilicate (TEOS) sol were characterized in detail in this study. The influence of different parameters on the formation of colloidal silica antireflective coatings by dip-coating technique has been investigated. All samples were characterized performing, transmission electron microscopy, UV-visible spectroscopy, atomic force microscopy, ellipsometric, total scattering and laser-induced damage threshold measurements. Herewith we present our recent results on synthesis of sol-gel solvents, coating fabrication and characterization of their optical properties.
Optical characterization of anti reflective sol-gel coatings fabricated using dip coating method
2007
In recent years, there has been a growing interest in further development of sol-gel method which can produce ceramics and glasses using chemical precursors at relative low-temperatures. The applications for sol-gel derived products are numerous. Department of General and Inorganic Chemistry with Laser Research Center of Vilnius University and Institute of Physics continues an ongoing research effort on the synthesis, deposition and characterization of porous solgel. Our target is highly optically resistant anti-reflective (AR) coatings for general optics and nonlinear optical crystals. In order to produce AR coatings a silica (SiO2) sol-gel has been dip coated on the set of fused silica substrates. The optical properties and structure of AR-coatings deposited from hydrolysed tetraethylorthosilicate (TEOS) sol were characterized in detail in this study. The influence of different parameters on the formation of colloidal silica antireflective coatings by dip-coating technique has been investigated. All samples were characterized performing, transmission electron microscopy, UV-visible spectroscopy, atomic force microscopy, ellipsometric, total scattering and laser-induced damage threshold measurements. Herewith we present our recent results on synthesis of sol-gel solvents, coating fabrication and characterization of their optical properties.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2018
We report the fabrication of nanoporous silica coatings with tunable refractive indices by a one-step basecatalyzed sol-gel process using tetraethoxysilane as the precursor, hexamethylisilazane as the modifier at ambient conditions. The advantages of the present method are inexpensive, etchant-free and without high temperature calcination treatment. Importantly, porosity of the coatings can be tunable by changing the monomer ratio of the starting solution, which makes them suitable for top layer of broadband AR coatings. The tri-wavelength broadband AR coating with the refractive indices of the bottom and top layers as 1.27 and 1.16 was achieved on a fused silica substrate, which possessed high transmittance of 99.6%, 98.0% and 99.3% at 351 nm, 527 nm and 1053 nm, respectively. Moreover, the double-layer coating showed significant stability, when tested with polydimethylsiloxane pollution in vacuum for a week. In addition, LIDT of the double-layer coating was up to ca. 19.0 J cm −2 at a 6.3 ns laser pulse of 351 nm wavelength. This double-layer AR coating possesses excellent broadband AR performance, high LIDT, and excellent vacuum stability, which can open a new avenue to explore applications in high-power laser systems.
Sol–gel preparation of PTMS modified hydrophobic and transparent silica coatings
Journal of Porous Materials, 2013
Wettability of solid surfaces is an important property, which depends on both the surface chemistry and surface roughness. The present paper describes the room temperature synthesis of dip coated water repellent silica coatings on glass substrates using phenyltrimethoxysilane (PTMS) as a co-precursor with two-step sol-gel process. Silica sol was prepared by keeping the molar ratio of tetraethylorthosilicate precursor, methanol solvent, acidic water (0.001 M oxalic acid) and basic water (12 M NH 4 OH) constant at 1:11.03:0.17:0.58 respectively, throughout the experiments and the PTMS weight percentage was varied from 0 to 15 %. It was found that with an increase in wt% of PTMS, the roughness and hydrophobicity of the films increased. However, the optical transmission decreased from 93 to 82 % in the visible range. The hydrophobic silica films retained their hydrophobicity up to a temperature of 386°C and above this temperature the films became hydrophilic. The hydrophobic silica thin films were characterized by taking into consideration the surface roughness studies, Fourier transform infrared spectroscopy, percentage of optical transmission, scanning electron microscopy, thermogravimetric-differential thermal analysis and contact angle measurements.
Journal of Physical Chemistry C, 2007
Porous silica coatings were prepared by acid-and base-catalyzed sol-gel method. Surface morphology studies by atomic force microscopy showed smooth surface for acid-catalyzed coatings while base catalysis resulted in coarse particle morphology. On increasing the tetraethyl orthosilicate to base molar ratio from 1:1 to 1:3, the mean particle size of the coating shifted from 30 to 100 nm while the pore size varied from 4.7 to 14 nm. Infrared spectral analysis exhibited a change in the ratio of integrated peak intensities of Si-O-Si to Si-OH in acid-and base-catalyzed silica coatings. Textural studies showed an increase in particle size and porosity with base concentration. Optical transmission and surface roughness of base-catalyzed samples were found to be higher than that of acid-catalyzed silica coatings.
Engineering and Technology Journal, 2021
The sol-gel-prepared silica incorporated into the RTV matrix demonstrated the optimal hydrophobic surface at contact angle 146°. Zeta potential analysis demonstrated the stability of nanoparticles at recorded average values of −41 to −50 mV. Some XRD peak intensities of hydrophobic coating (RTV silicone rubber/silica) coated glass differed from the neat component (RTV or silica). XRD differences between the neat materials and their corresponding composite demonstrate satisfactory incorporation and a cohesive layer that produced significant bonding between components. This works aims to investigate the influence of three different categories of silica, namely, precipitated silica, fumed silica and nanosilica prepared via solgel process, for hydrophobic application in this work. Nanosilica was characterised using scanning electron microscopy, Fourier transform infrared spectroscopy, particle size and zeta potential. Diluted silicone rubber (roomtemperature vulcanising silicone...