Base Catalyzed Sol Gel Process Research Articles

Tailoring the Morphology of Monodisperse Mesoporous Silica Particles Using Different Alkoxysilanes as Silica Precursors.

The hard template method for the preparation of monodisperse mesoporous silica microspheres (MPSMs) has been established in recent years. In this process, in situ-generated silica nanoparticles (SNPs) enter the porous organic template and control the size and pore parameters of the final MPSMs. Here, the sizes of the deposited SNPs are determined by the hydrolysis and condensation rates of different alkoxysilanes in a base catalyzed sol-gel process. Thus, tetramethyl orthosilicate (TMOS), tetraethyl orthosilicate (TEOS), tetrapropyl orthosilicate (TPOS) and tetrabutyl orthosilicate (TBOS) were sol-gel processed in the presence of amino-functionalized poly (glycidyl methacrylate-co-ethylene glycol dimethacrylate) (p(GMA-co-EDMA)) templates. The size of the final MPSMs covers a broad range of 0.5-7.3 µm and a median pore size distribution from 4.0 to 24.9 nm. Moreover, the specific surface area can be adjusted between 271 and 637 m2 g-1. Also, the properties and morphology of the MPSMs differ according to the SNPs. Furthermore, the combination of different alkoxysilanes allows the individual design of the morphology and pore parameters of the silica particles. Selected MPSMs were packed into columns and successfully applied as stationary phases in high-performance liquid chromatography (HPLC) in the separation of various water-soluble vitamins.

Synthesis and Characterization of Erbium-Doped Silica Films Obtained by an Acid-Base-Catalyzed Sol-Gel Process.

Erbium-doped silica films were synthesized using a two-step sol-gel methodology that involved acid and base catalysts, with erbium concentration ranging from 0.2% to 6% and annealing temperatures varying from 500 °C to 900 °C. The photoluminescence spectra showed that the samples exhibiting efficient emission were annealed at 800 °C and 900 °C and doped with 3% and 6% erbium. The X-ray diffraction analysis revealed that the internal structure of the films was influenced by the different annealing temperatures and the doping concentrations. Samples with dominant 4f transitions were modelled. The results suggest that the proposed method is a promising approach for the synthesis of erbium-doped silica films with potential applications in optical devices.

Evaluation the mechanical and electrochemical anti-corrosion properties of polydimethylsiloxane/SiO2 gel coated carbon steel rebar in concrete pore solution

The aim of the current study was to evaluate the mechanical and electrochemical anti-corrosion properties of carbon steel rebar in concrete pore solution after the steel was coated with polydimethylsiloxane/SiO2 (PDMS/SiO2) hybrid material as an organic–inorganic hybrid coating. PDMS/SiO2 hybrid material was prepared using a base-catalyzed sol-gel process with different SiO2 contents (0 wt%, 5 wt%, 10 wt%, 15 wt% and 20 wt%). Mechanical studies showed that the synergetic effect of PDMS and SiO2 increased the values of yield stress and Young's modulus and decreased the elongation at break. Electrochemical studies using EIS and polarization tests showed that the coated steel rebar samples had higher corrosion resistance than the uncoated steel sample, illustrating that the PDMS/SiO2 coating exhibits great barrier properties in corrosion reactions and indicates more corrosion resistance in the CPS corrosive media, and increasing the SiO2 content in the hybrid coating from 5 to 15 wt% promotes corrosion inhibition effectiveness. The steel rebar sample coated with the PDMS/SiO2 hybrid sample with 15 wt% SiO2 content as the optimal amount of SiO2 showed the highest corrosion resistance and inhibition efficiency (95.81%) values. SEM micrographs of the surface morphology of uncoated and PDMS/15SiO2 coated steel rebar surface samples immersed in CCP solutions for 24 h revealed that the PDMS/15SiO2 coating effectively inhibits steel corrosion in CCP solution due to less corrosive ion penetration to the steel surface.

Comparative Studies of the Dielectric Properties of Polyester Imide Composite Membranes Containing Hydrophilic and Hydrophobic Mesoporous Silica Particles.

In this paper, comparative studies of hydrophilic and hydrophobic mesoporous silica particles (MSPs) on the dielectric properties of their derivative polyester imide (PEI) composite membranes were investigated. A series of hydrophilic and hydrophobic MSPs were synthesized with the base-catalyzed sol-gel process of TEOS, MTMS, and APTES at a distinctive feeding ratio with a non-surfactant template of D-(-)-Fructose as the pore-forming agent. Subsequently, the MSPs were blended with the diamine of APAB, followed by introducing the dianhydride of TAHQ with mechanical stirring for 24 h. The obtained viscous solution was subsequently coated onto a copper foil, 36 μm in thickness, followed by performing thermal imidization at specifically programmed heating. The dielectric constant of the prepared membranes was found to show an obvious trend: PEI containing hydrophilic MSPs > PEI > PEI containing hydrophobic MSPs. Moreover, the higher the loading of hydrophilic MSPs, the higher the value of the dielectric constant and loss tangent. On the contrary, the higher the loading of hydrophobic MSPs, the lower the value of the dielectric constant with an almost unchanged loss tangent.

Long-Term Performance and Stability of Interlayer-Free Mesoporous Silica Membranes for Wetland Saline Water Pervaporation.

Wetland water is an alternative water resource around wetland areas. However, it is typically saline due to seawater intrusion and contains high natural organic matter (NOM) that is challenging to treat. This study evaluated the stability of interlayer-free mesoporous silica matrix membranes employing a dual acid–base catalyzed sol–gel process for treatment of saline wetland water. The silica sols were prepared under a low silanol concentration, dip-coated in 4 layers, and calcined using the rapid thermal processing method. The membrane performance was initially evaluated through pervaporation under various temperatures (25–60 °C) using various feeds. Next, the long-term stability (up to 400 h) of wetland saline water desalination was evaluated. Results show that the water flux increased at higher temperatures up to 6.9 and 6.5 kg·m−2·h−1 at the highest temperature of 60 °C for the seawater and the wetland saline water feeds, respectively. The long-term stability demonstrated a stable performance without flux and rejection decline up to 170 h operation, beyond which slow declines in water flux and rejection were observed due to fouling by NOM and membrane wetting. The overall findings suggest that an interlayer-free mesoporous silica membrane offers excellent performance and high salt rejection (80–99%) for wetland saline water treatments.

ВЫСОКОГИДРОФОБНЫЕ ПОЛИУРЕТАНОВЫЕ ПОКРЫТИЯ, ПОВЕРХНОСТНО МОДИФИЦИРОВАННЫЕ ЗОЛЯМИ АМИНОСИЛАНОВ

In this article, highly-hydrophobic polyurethane coatings with low limiting wetting angle hysteresis were received by the surface modification with sol-gel technology. The influence of sol components on structure of obtained gels in acid- and base-catalyzed sol-gel process examined by both Fourier-infrared and nuclear magnetic resonance spectroscopy. Influence of tetraethoxysilane and 3-aminopropyltriethoxysilane ratio on wetting of xerogels coating was shown. Particle size distribution in receiving sols was investigated. By atomic-force microscopy and scanning electron microscopy the topography and the morphology of the surface of polyurethane coatings modified by xerogels were studied

Polyethylenimine wrapped mesoporous silica loaded benzotriazole with high pH-sensitivity for assembling self-healing anti-corrosive coatings

The aim of this work is to develop a self-healing coating doped with pH-sensitive nanocontainers for the active corrosion protection of mild steel. A pH-sensitive carboxyl-functionalized mesoporous silica nanomaterials (MSNs-COOH) was prepared via chemical modification of mesoporous silica nanomaterials (MSNs) which was synthesized in a tetraethyl orthosilicate (TEOS) solution via base catalyzed sol-gel process. Benzotriazole (BTA) molecules were loaded into the internal pores of the prepared MSNs-COOH. Then the BTA-loaded MSNs-COOH were wrapped by the highly branched polyethylenimine (PEI) to obtain the nanocontainers of BTA@MSNs-COOH-PEI. SEM, TEM, DLS, XRD, nitrogen adsorption-desorption isotherms, TGA and FT-IR analyses were employed to characterize the as-prepared nanocontainers. The pH-sensitive releasing property of BTA@MSNs-COOH-PEI was studied using UV–vis spectroscopy, which indicates that the releasing rate of BTA from BTA@MSNs-COOH-PEI can be accelerated under alkaline conditions. Afterwards, a self-healing coating was fabricated based on the epoxy resin primer doped with BTA@MSNs-COOH-PEI which can release BTA inhibitor once localized corrosion occurs. Finally, the active anti-corrosion performance of the as-prepared coating was confirmed by EIS measurements and salt spray tests. The self-healing coating prepared in this work brings a new sight for elaborate design of active anti-corrosion coatings.

Phenazine-1-carboxamide functionalized mesoporous silica nanoparticles as antimicrobial coatings on silicone urethral catheters

Microbial infections due to biofilms on medical implants can be prevented by antimicrobial coatings on biomaterial surfaces. Mesoporous silica nanoparticles (MSNPs) were synthesized via base-catalyzed sol-gel process at room temperature, functionalized with phenazine-1-carboxamide (PCN) and characterized by UV-visible, FT-IR, DLS, XRD spectroscopic techniques, SEM, TEM, TGA and BET analysis. Native MSNPs, PCN and PCN-MSNPs were evaluated for anti-Candida minimum inhibitory concentration (MIC), minimum fungicidal concentration (MFC), Candida albicans (C. albicans) biofilms and C. albicans-Staphylococcus aureus (S. aureus) polymicrobial biofilm inhibition. PCN-MSNPs were four-fold effective (MIC 3.9 µg mL−1; 17.47 µM) and MFC (7.8 µg mL−1; 34.94 µM) as compared to pure PCN (MIC 15.6 µg mL−1; 69.88 µM) and MFC (31.2 µg mL−1; 139.76 µM). PCN-MSNPs inhibited in vitro C. albicans MTCC 227-S. aureus MTCC 96 biofilms at very low concentration (10 µg mL−1; 44.79 µM) as compared to pure PCN (40 µg mL−1; 179.18 µM). Mechanistic studies revealed that PCN induced intracellular ROS accumulation in C. albicans MTCC 227, S. aureus MTCC 96 and S. aureus MLS-16 MTCC 2940, reduction in total ergosterol content, membrane permeability, disruption of ionic homeostasis followed by Na+, K+ and Ca2+ leakage leading to cell death in C. albicans MTCC 227 as confirmed by confocal laser scanning micrographs. The silicone urethral catheters coated with PCN-MSNPs (500 µg mL−1; 2.23 mM) exhibited no formation of C. albicans MTCC 227 - S. aureus MTCC 96 and C. albicans MTCC 227 - S. aureus MLS -16 MTCC 2940 biofilms. This is the first report on PCN-MSNPs for use as antimicrobial coatings against microbial adhesion and biofilm formation on silicone urethral catheters.

A hydrophobic ultralow refractive-index silica coating towards double-layer broadband antireflective coating with exceptionally high vacuum stability and laser-induced damage threshold

We report the fabrication of nanoporous silica coatings with tunable refractive indices by a one-step base-catalyzed 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.

Rational design and fabrication of highly transparent, flexible, and thermally stable superhydrophobic coatings from raspberry-like hollow silica nanoparticles

Multifunctional coatings with superhydrophobicity, high transparency, thermal stability, flexibility, and ultralow refractive index have been investigated for many years. They have promising applications in industries such as in electronic and optical devices, photonic materials, and templates for fabricating biological and chemical sensors. However, the relatively complex preparation technology of these coatings or difficult to possess these properties simultaneously are still the main factors that limit their wide application. In this paper, we report a facile atmospheric approach to create transparent multifunctional raspberry-like particulate coatings with a low refractive index, which were obtained via one-pot base-catalyzed sol-gel process using tetraethyl orthosilicate (TEOS) and 1H, 1H, 2H, 2H-perfluorooctyltrimethoxysilane (POTS) as co-precursors. The excellent superhydrophobicity, mechanical flexibility, self-cleaning property, thermal and chemical stability of the as-fabricated coatings were demonstrated. The refractive indices of coatings can be easily tuned at a range of 1.07–1.16. Particularly, the resulted samples on the K9 glasses exhibited superhydrophobicity with a water contact angle (WCA) of 162° when the scale ratio of the POTS and TEOS was 1.0. The superhydrophobicity of the as-prepared coatings could last for more than half a year under indoor condition, demonstrating the long stability of the superhydrophobicity. Furthermore, we demonstrated that this simple efficient method could be extended to different substrates, including K9 glass, Polyvinyl chloride (PVC), stainless steel, aluminum alloy, and gingko leaf, to achieve superhydrophobicity. Interestingly, the superhydrophobicty of the coatings transferred to superhydrophilicity (WCA < 5°) by calcination at 500 °C, which resulted in a good antifogging property. Moreover, the coatings were not sensitive to the strong acid (pH = 1) and kept their superhydrophobic state for a long time (over 80 min). The coatings on PVC retain their excellent water-repellency after multiple bending cycles. Also, these coatings produced a fair transparency consisting of more than a 2.0% increase in optical transmittance in the visible-near infrared spectral range. Our study is promising building blocks for large-area, mechanical flexible, ultralow-refractive-index, superhydrophobic and environment-resistant surfaces.

Synthesis of a fluorine-free polymeric water-repellent agent for creation of superhydrophobic fabrics

A non-fluorinated polymeric alkylsilane, poly(isobutyl methacrylate-co-3-methacryloxypropyltrimethoxysilane) (PIT), is designed and synthesized to replace the commercial long-chain perfluoroalkylsilane (FAS) water-repellent agent. The superhydrophobic polyester fabrics are prepared by anchoring sol-gel derived silica nanoparticles onto alkali-treated polyester fabric surfaces and subsequently hydrophobilizing with PIT, using FAS as control. The surface chemical composition, surface morphology, wetting behavior and durability of the modified polyester fabrics are characterized by scanning electron microscopy (SEM), X-ray photoelectron spectrophotometer (XPS) and video-based contact angle goniometer, respectively. The results show that a porous silica layer could be successfully fabricated onto the surface of polyester fabric through base-catalyzed sol-gel process with tetraethoxysilane (TEOS) as precursor, incorporating additional nanostructured roughness essential for superhydrophobicity. At the same time, such a silica primer layer could provide both secondary reactive moieties (−Si − OH) for the subsequent surface hydrophobization and acceptable adhesion at the silica-polyester fabric interface. When silica modified polyester fabric (SiO2@ fabric) is hydrophobized by PIT solution (10mg/mL), excellent water-repellency could be obtained. The water contact angle is up to 154° and the sliding angle is about 5°. Compared with small molecule water-repellent agent FAS, PIT modified SiO2@ fabric exhibits greatly improved solvent resistance under ultra-sonication, abrasion and simulated laundering durability. The anti-stain property of PIT-modified SiO2@ fabric is also evaluated by using different aqueous colored solutions.

Design and synthesis of temperature-responsive polymer/silica hybrid nanoparticles and application to thermally controlled cellular uptake

This study reports the development of temperature-responsive polymer/silica hybrid nanoparticles and their application to temperature-dependent intracellular uptake of hydrophobic encapsulated fluorescence molecules. Amphiphilic diblock copolymer comprising a temperature-responsive segment, poly(N-isopropylacrylamide-co-N,N-dimethylacrylamide) [P(NIPAAm-co-DMAAm)] and a trimethyoxysilyl-containing hydrophobic segment was synthesized (PBM-b-ND); this amphiphilic diblock copolymer self-assembled in an aqueous solution, and temperature-responsive polymer/silica hybrid fluorescence nanoparticles were fabricated via a base-catalyzed sol–gel process. The fluorescence probe rhodamine DHPE or boron dipyrromethene derivative was encapsulated into the polymer core with a silica network in a stable manner. Other types of polymer/silica hybrid fluorescence nanoparticles were also developed using either homo-PNIPAAm (PBM-b-N) or homo-PDMAAm (PBM-b-D) segments, instead of P(NIPAAm-co-DMAAm). While PBM-b-D did not exhibit a temperature-dependent phase transition (hydrophilic characteristic), PBM-b-N and PBM-b-ND exhibited temperature-dependent phase transition (hydrophilic/hydrophobic) at 32°C and 38°C, respectively. The cellular uptake of PBM-b-N was clearly observed at both 37°C and 42°C, while the cellular uptake of PBM-b-D was minimal at these temperatures. On the other hand, significant enhancement in the intracellular uptake of PBM-b-ND was observed at 42°C, compared to its uptake at a lower temperature of 37°C. These results indicated that temperature-responsive polymer/silica hybrid nanoparticle, PBM-b-ND demonstrate potential for applications in theranostics with cancer therapy via the combination of local drug delivery and local hyperthermia, as well as for monitoring treatment effectiveness with fluorescence imaging.

Development of hydrophobic and optically transparent monolithic silica aerogels for window panel applications

In the present paper, highly transparent, monolithic and hydrophobic silica aerogel monoliths were prepared by using tetraethoxysilane (TEOS) as precursor and methyltriethoxysilane (MTES) as co-precursor with different MTES/TEOS molar ratios (M) by two-step acid–base catalyzed sol–gel process followed by supercritical alcohol drying. The molar ratio of TEOS, ethanol (EtOH), water (0.001 M oxalic acid catalyst) and ammonium hydroxide (1 M NH4OH) was kept constant at 1:5:3.5:3.5 respectively, while the molar ratio of MTES/TEOS (M) was varied from 0 to 0.75. It has been observed that as the M value increases, the gelation time increases. It has been found that lower (0.25) M values resulted in highly transparent (optical transmission >90 % for a 10 mm thick sample at 700 nm wavelength) and negligible volume shrinkage ( 10 % volume shrinkage but excellent hydrophobicity. A good compromise of acceptable optical transmittance (~87 % optical transmission at 700 nm wavelength for a 10 mm thick sample) with negligible volume shrinkage (6 %) were obtained at M = 0.50. The hydrophobicity of the aerogels was tested by measuring the contact angle between a water droplet and silica aerogel surface. The hydrophobicity was confirmed by Fourier transform infra-red spectroscopy and contact angle measurements. the aerogels have been characterized by percentage of volume shrinkage, optical transmittance, scanning electron microscopy, thermal conductivity measurements and thermogravimetric analysis and differential thermal analysis.

Sol–gel preparation of moisture-resistant antireflective coatings from novel hollow silica nanoparticles

In this study, a simple approach was developed to prepare hollow silica nanoparticles (HSNs) sols via a one-step base-catalyzed sol–gel process using methyltriethoxysilane and tetraethoxysilicate as co-precursors. The prepared sols were suitable for large-area processing with ease of antireflective (AR) coating and being directly applicable without requiring any pre- or post-treatment. AR coatings were dip coated on K9 glasses from these sols. Furthermore, AR coatings were intrinsically hydrophobic with static water contact angles up to 126.5° on the smooth K9 glass. A particle growth mechanism of the hybrid HSNs was proposed, and the relationship between the microstructure of HSNs and the properties of AR coatings was investigated. These AR coatings with relatively excellent AR properties and improved moisture resistance were useful in solar cells, low-cost electronics, and optical devices.

Effect of SiCl4 on the preparation of functionalized mixed-structure silica from monodisperse sol–gel silica nanoparticles

Mesoporous functionalized nanoparticles (nanosilica) and functionalized mixed-structure silica with surface Si–Cl groups were prepared via a SiCl4 hydrolysis base-catalyzed sol–gel process. This study presents hierarchically structured systems formed via growth and self-assembly of functionalized silica nanospheres on the surface of Sylopol-948, generating functionalized mixed-structure silica. The fabricated materials were characterized by nitrogen adsorption, small angle X-ray (SAXS), dynamic light scattering (DLS), zeta potential (ZP), infrared spectroscopy (FT-IR), and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM–EDX). The incorporation of Si–Cl groups (0.02–0.43 Cl/Si) on the surface—to functionalize the nanoparticles and modify their properties—was confirmed by SEM–EDX and cyclic voltammetry. In functionalized mixed-structure silica, the SBET value (567m2/g) increases, particle size (13.6–17.2nm) decreases and surface charge (−9.0mV) diminishes as SiCl4 concentration increases. In functionalized nanosilica, a lower SiCl4 concentration results in a higher SBET value (730.6m2/g), smaller nanoparticle size (6.0–12.4nm) and higher surface charge (−22.9mV). These materials were experimentally compared and found to demonstrate improved characteristics compared to Stöber nanosilica, non-functionalized mixed-structure silica, and Sylopol-948.

Sol-Gel Preparation of PHFBMA/PFG/Silica Coatings with Durable Short-wave-band Antireflective Performance

A new silica shortwave-band antireflective (AR) coating with durable optical performance on fused silica substrate was prepared by a base-catalyzed Sol-Gel process using tetraethyl orthosilicate (TEOS) as a precursor. 1H, 1H, 12H, 12H-perfluoro-dodecane-1, 12-diol (simplified as PFG) was used to control the structure and size of the sil- ica particles in the sols, and hence decreased the refractive indices of the coatings. After Poly (2, 2, 3, 4, 4, 4-hexafluorobutyl) methacrylate (PHFBMA) being introduced into the silica sols, the AR coatings could retain a transmission about 99.9% at about 300 nm. At the same time, the transmission stability of the coatings was improved significantly, which were tested in a moisture environment and an organic-containing vacuum chamber, respectively.

Influence of hydrophobic characteristic of organo-modified precursor on wettability of silica film

The objective of this study is to design new hybrid silica materials as templates with hydrophobic properties, prepared at room temperature by a base catalyzed sol–gel process. As silica sources, organoalkoxysilanes functionalized with short hydrophobic chains were used: tetraethylorthosilicate (TEOS), methyltriethoxysilane (MTES), vinyltriethoxysilane (VTES), octyltriethoxysilane (OTES) and isobutyltriethoxysilane (iTES). It was shown that hydrophobicity of the functionalized silica nanoparticles increased as a function of length of the aliphatic chains (MTES < iTES < OTES) or when, instead of a hydrophobic alkyl chains (substituting group of silica precursors), a monounsaturated group was used (VTES). It was observed that the samples responded in a specific way to each type (hydrophilic or hydrophobic) of the dropped liquid. Even though the experiments were limited to short hydrocarbon chains, they showed that there is a threshold to reach high hydrophobicity of the hybrid surface.

Improvement in Mechanical Property of SiO2 Films Prepared by Sol-Gel

Silica films prepared by the base catalyzed sol–gel process show poor mechanical property. In this study, silica anti-reflective films with good mechanical property have been prepared by the catalyzed sol–gel process with dimethyl formamide added as drying control chemical additives. The silica sol was first dip deposited onto substrate to form films on both sides of the substrate and then subjected to thermal treatment. After thermal treatment, the film was achieved due to the formation of porous structure in the resultant film as a result of decomposing tetraethylorthosilicate and dimethyl formamide. Nano-indenter measurement shows that the Young’s modulus and hardness of base catalyzed films are 10-20GPa and 0.25-0.55GPa, respectively. But the films added with dimethyl formamide are much better than those films derived from base-catalyzed silica sols, the Young’s modulus and hardness are 32-39GPa and 1.22-1.47GPa, respectively. The good mechanical properties make such films potential in both military and civil applications.

A novel route to prepare weather resistant, durable antireflective films for solar glass

Silica antireflective coatings by the base catalyzed sol–gel process show poor mechanical property. In this study, the base-catalyzed sol was modified by acid-catalyzed polysiloxane and nano-TiO2 sol. The single layer antireflective films were prepared using spray coating technology, the effects of transmission speed on the optical performance of the films were studied. The results show that the films derived from the modified sol have an excellent weather resistance. Its degradation of transmittance after damp-heat test is only 0.23%. The maximum transmittance of the antireflective solar glass with single layer coating is about 95.02% at 565nm wavelength, which is about 3.36% higher than the substrate glass. The adhesion of the film is 5B and the pencil hardness is equal or higher than 3H. High transmittance, good mechanical properties and excellent durability make the films be suited to solar glass.

Novel pathways for the preparation of silica antireflective films: Improvement in mechanical property

Silica antireflective films by the base catalyzed sol–gel process show poor mechanical property. In this study, silica antireflective films with good mechanical property have been prepared by the acid catalyzed templating sol–gel process. The single-layer film was deposited from an acid-catalyzed silica sol solution with polymer F127 incorporation. The silica sol was first dip deposited onto substrate to form films on both sides of the substrate and then subjected to thermal treatment at 500 °C. After thermal treatment, the abrasion resistant antireflective film was achieved due to the formation of porous structure in the resultant film as a result of decomposing F127. Optical spectroscopic measurement shows that the coated glass with maximum transmittance of 99.5% has been obtained. Nanoindenter measurement shows that the elastic modulus and hardness of films are 16 GPa and 1.3, respectively, which are much better than those films derived from base-catalyzed silica sols. The high transmittance and good mechanical property make such films potential in both military and civil applications.