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XRD pattern of single, mixed and multilayer thin films on PMMA, a PMMA, b SiO2, c TiO2, d SiO2–TiO2, e TiO2/SiO2–TiO2/SiO2
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Single and multilayer (SiO2, TiO2, SiO2–TiO2, TiO2/SiO2–TiO2/SiO2) films were deposited on polymer substrate poly-methyl methacrylate (PMMA) at room temperature by sol–gel method. Optical micrographs show that spin-coated nanoparticle thin films have homogeneous surface with good adhesion with PMMA substrate. Scanning electron microscope results sh...
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Citations
... Wang et al. [17] obtained superhydrophobic transparent film on a glass substrate by hydrolyzing the tetraethoxysilane (TEOS) in an acidic environment and then reacted with hexamethyldisilazane (HMDS). Islam et al. [18] reported that nanoparticle optical coating of silica and titania on polymer substrate PMMA can be prepared via a sol-gel method, at room temperature. Ortelli et al. [19] reported the preparation of organic-inorganic hybrid compositions (ceramers) through the sol-gel process, using different alkoxysilane precursors (trimethoxymethylsilane (TMEOS), (3-aminopropyl) trimethoxyalkoxysilane (APTMS) and tetraethoxysilane (TEOS)). ...
... Furthermore, nano scale geometries give a guarantee for the antireflective properties. Additionally, it was demonstrated that the homogeneous stable coatings with low reflectance (<2%) and controllable refractive index properties of this method make it feasible to obtain antireflective coating on plastic with optimal performance at low temperature [18]. Zhang et al. [32] developed a novel nanocomposites coating with a closed-pore structure by a sol-gel dip-coating method, silica sol synthetized in acidic medium. ...
Transparent and antireflective coatings were prepared by deposition of modified silica
materials onto polyvinyl chloride (PVC) substrates. These materials were obtained by the sol-gel route in acidic medium, at room temperature (25 oC), using different alkoxysilanes with various functional groups (methyl, vinyl, octyl or hexadecyl). Physicochemical and microstructural properties of resulted silica materials and of thin coatings were investigated through Fourier Transforms Infrared Spectroscopy (FTIR), UV-Vis spectroscopy, Thermal Gravimetric Analysis (TGA), Dynamic Mechanical Analysis (DMA), Atomic ForceMicroscopy (AFM) and ellipsometricmeasurements.Wetting behaviors of
the silica coatings were evaluated by measurement of static contact angle against water. FTIR spectra of materials confirmed the high degree of cross-linking that result from the formation of the inorganic backbone through the hydrolysis and polycondensation reactions together with the formation of the organic network. These sol-gel silica coatings showed a reduction in the reflectance (10%) compared with uncoated PVC substrate. AFM reveals that the films are uniform, and adherent to the substrate, but their morphology is strongly influenced by the chemical composition of the coating matrices.
These silica coatings can be useful for potential electronic and optical devices.
... Furthermore, refractive index for each matrix is calculated by the Fresnel formula and plotted profiles are shown in Fig. 6-II(a-d) for SiO 2 , SiO 2 -BPB, SiO 2 -CR and SiO 2 -PR matrices. The refractive index for SiO 2 matrix is observed ∼1.34 at 632.8 nm which is lower than the literature value of silica ∼1.47 [27]. After encapsulation, variations are observed such as 1.33 for SiO 2 -BPB, 1.36 for SiO 2 -CR and 1.35 for SiO 2 -PR matrices. ...
Owing to the fast responsive fiber optical pH sensing characteristics, silica porous matrix is synthesized through a low temperature sol-gel technique. Three different pH dyes namely bromophenol blue (BPB), creosol red (CR) and phenol red (PR) are encapsulated in silica matrix to observe their behavior on structural and optical characteristics of host matrix. FESEM/EDS and AFM analyses reveal that CTAB assisted silica matrix before and after dyes encapsulation has crack-free and porous morphology. The creosol red encapsulated silica matrix (SiO2-CR) has small average surface roughness (Ra) ∼1.05 nm with ultra-thin texture ∼4.06 nm compared to other dyes. FTIR analysis shows that higher content of SiOH group in SiO2-CR matrix shows more hydrophilic features than others matrices. BET analysis indicates that nano-porous structures possess extremely large surface area ∼450 m²/g, and they display specific selectivity towards each dye. UV–vis analysis shows that SiO2-CR matrix has low refractive index 1.36 and high transparency 81% at 632.8 nm with a certain extent of absorption in the visible region. The pH-responsive matrices are deposited onto the PCS (Plastic Clad Silica) optical fibers. The performance of the prepared devices is assessed by measuring their response in the pH range of 1–12. SiO2-PR matrix coated fiber sensor exhibited rapid response of time 0.51 s at pH 12 and 0.17 s at pH 1. The prepared pH sensor has linear response with coefficient of determination (R²) ∼ 0.90 at 440 nm within pH 1–12. Experimental findings suggest that SiO2-PR matrix has more sensing potential at dynamic pH range 1–12 than SiO2-CR matrix and SiO2-BPB matrix.
... Silica matrix and Si-CR matrix refractive index profiles are illustrated in Fig. 6-II(a, b) within the range of 400 nm-700 nm A very low value of refractive index 1.35 at 550 nm was calculated for silica matrix and 1.38 at 550 nm for Si-CR matrix. A high degree of porosity between the particles is responsible for low refractive index [33]. ...
This research work is concerned with the synthesis of cetyl trimethylammonium bromide (CTAB) assisted silica nanomatrix and creosol red (CR) immobilization in silica nanomatrix. The synthesized nanomatrices are systematically characterized by FESEM/EDS analysis, AFM, FTIR, TGA, BET and UV–vis spectroscopy. FESEM analysis suggests the porous structure network of CTAB assisted silica occupied by CR species after immobilization. Silicon and oxygen signals along with CTAB and CR species by EDS spectra confirm a strong interaction with each other. AFM analysis exhibited the crack-free smooth surface with low average surface roughness ∼2.25 nm which decreased down to ∼1.98 nm. The thickness ∼12 nm is calculated after CR immobilization. FTIR spectroscopy confirmed the presence of silica molecules and CR species bonding after immobilization in silica matrix. BET analysis confirmed the mesoporosity of synthesized matrices with surface area of 458 m²/g, after immobilization. TGA and UV–vis analysis show that thermally stable CR immobilized matrix is 82% transparent and has low refractive index ∼1.38. The proposed sensing device has linear sensitivity ∼90 (a.u.)/pH unit with coefficient of determination (R²) ∼0.98 within pH 1–9. Fast response has been observed at 0.2 s in pH 9 with color change behavior and 98% repeatability identify that the coated matrix has potential in opto-chemical sensing device.
... Low value of refractive index 1.36 at 550 nm was observed for silica nano-matrix and 1.35 at 550 nm for BPB encapsulated silica matrix. A high degree of porosity is responsible for low refractive index or probably voids between the particles are responsible for the reduction in refractive index of the coating, as observed in our previous studies [44]. ...
Thermally stable surfactant modified silica nano-matrix is synthesized by the sol–gel method at low temperature. The surfactant such as cetyltrimethylammonium bromide (CTAB) assisted silica matrix is encapsulated with bromophenol blue (BPB) for sensing activities. Prepared nano-matrix consists of numerous morphological structures such as a pseudo-spherical, hierarchal and islands. The morphology of mesoporous high surface area matrices is strongly affected by CTAB, BPB dye and the aging conditions that determine the transformation from disordered silica nano-matrix morphologies to ordered encapsulated structures. Furthermore, smooth surface matrices with low surface roughness 1.2 nm, low refractive index 1.36, large pores and small dimensions of heteroatoms contribute to the stable sensing activities. The response of coated fiber optic is determined at dynamic pH range 1–12. The prepared sensor has reversibility/repeatability, stability and fast response time of approximately 0.25 s in basic media. The accuracy of sensing device measurements in household ammonia solution and the borax solution suggested that prepared device has clear potential for daily life usage.
... The refractive index is an important parameter of the coating [1], and it is necessary to obtain an appropriate refractive index for broadband antireflective (AR) coatings, optical instruments and solar cells in the ambient air [2]. The relationship between the refractive index of the coatings and the reflectivity of incident light are determined by the Fresnel's law [3]. ...
... The refractive index is an important parameter of the coating [1], and it is necessary to obtain an appropriate refractive index for broadband antireflective (AR) coatings, optical instruments and solar cells in the ambient air [2]. The relationship between the refractive index of the coatings and the reflectivity of incident light are determined by the Fresnel's law [3]. ...
... N2 Adsorption isotherms of (a) as-synthesized (b) after heating at 150 • C (c) after heating at 250 • C. sion can be seen for as-deposited sample, which is probably due to the scattering from a few large pores. Moreover, larger grain size leads to increase in transmission [24]. ...
This work highlights the versatility of sol-gel-derived nanocomposite silica-titania host matrix along with functionalized organic dyes i.e., bromophenol blue (C19H10Br4O5S), phenol red (C19H14O5S), cresol red (C21H17NaO5S) and phenolphthalein (C20H14O4) encapsulation with surfactant CTAB for pH sensing. The synthesized matrices before and after heat treatment (at 150 °C and 250 °C) are analyzed for chemical and physical uniformity; observed as stable, homogeneous, low surface roughness and with functionalized nano-pore surfaces. Particle size distributions in the range of 2.28 nm, 2.73 nm and 2.54 nm are established. Surface analysis shows that the nanoparticles are uniformly distributed on the surface of the mesoporous channel systems with high surface area 400 m²/g, and highly accessible pore system which has more capability to sense the broad pH range. The films show good optical qualities in the visible region with tunable refractive indices 1.57, 1.52-and 1.56. The response of the prepared sensor even shows stability towards higher pH value 12 and has linear relationship with correlation coefficient R² ∼0.9341. The sensitivity of the proposed pH sensor is observed to be 0.614 mV/pH.
... The role of boehmite, as a filler, in some organic matrices has been evaluated [13,18,19]. Polymethyl methacrylate (PMMA) as one of the most important acrylates has been located in the heart of the different studies due to its outstanding optical [20,21] and mechanical features but suffers from weak thermal stability [22]. The enhancement of generally thermal properties of polymers is the main concern, chiefly in the fields of the building, civil and electrical engineering, transportation, and food packaging [23][24][25][26][27][28]. ...
A method to acquire polymethyl methacrylate/Boehmite hybrid nanoparticles with well-controlled morphology synthesized directly from their relevant precursors (methyl methacrylate and aluminum nitrate) via an aqueous one-pot process is proposed which considerably shorten the number of steps and render substantial commercial benefits. Silane coupling agent was applied to yield a better compatibility between the organic-inorganic counterparts that confirmed by fourier transform infrared spectroscopy spectra with the chemical bond of Si–O–Al as the main link between organic and inorganic moieties. Thermal stability, morphology study, and microhardness of (polymethyl methacrylate/Boehmite) nanohybrids were also evaluated using thermogravimetric analysis, field emission scanning electron microscopy, and Vickers hardness experiments. Field emission scanning electron microscopy analysis confirmed the formation of polymethyl methacrylate/Boehmite nanostructure with an excellent dispersion of inorganic particles in an organic matrix with high uniformity. The uniform particles including different morphologies (cauliflower, semispherical, and bean–like particles) obtained by adjusting pH, surfactant, and sequence of precursor addition. Under acidic pH 4 and basic pH 8, the cauliflower and semispherical particles were made while bean-like particles obtained when polymethyl methacrylate particles formed after boehmite. The presence of boehmite improved the thermal stability and microhardness of hybrid. The microhardness of hybrid increased more than 44% with increasing just 5% boehmite.
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... Low value of refractive index 1.34 at 632.8 nm was observed for silica matrix and 1.33 at 632.8 nm was observed for phph encapsulated silica matrix. Probably, voids between the particles are responsible for the reduction in refractive index of the coating, as observed in our previous studies [24,25]. However, the refractive index of both samples is much lower than that of literature values of silica 1.47 and phenolphthalein 1.67 [26,27] meaning that the fabricated samples have a porous structure. ...
Exploration of novel meso-materials with higher surface areas is a major challenge in the rapidly expanding field of opto-chemical sensor devices. Therefore, synthesis and growth mechanism of surfactant CTAB assisted sol-gel based silica and phenolphthalein encapsulated silica nanoparticles (NPs) and their optical and pH sensing activities is reported at low temperature in this present communication. Hierarchical/ordered structures/architectures are observed after encapsulation of phenolphthalein by FE-SEM analysis. AFM analysis exhibits the formation of porous nanostructures with average surface roughness Ra ∼5.15 nm which is reduced to Ra ∼4.98 nm after encapsulation of phenolphthalein, whereas, particle size increased from 8 nm to 13 nm. N2 adsorption isotherms explain the meso-porous nature of the matrix with high surface area value of 443 m²/g with a pore volume of 0.93 cm³/g and pore diameter of 85.59 Å. Experimental findings show that the prepared meso-silica-phenolphthalein frameworks have high thermal stability, low refractive index (1.33) with good optical transparency of 83%. Furthermore, the evanescent wave is used to selectively excite the phph molecules encapsulated in silica matrix and deposited on the Plastic Clad Silica fiber as cladding for sampling the aqueous media (pH solutions 2–12) surrounding the fiber. Highest sensing response is optimized for pH 12 within 1s with pink color indication. The improved structural and optical characteristics identify that the prepared optochemical nanosensor device has potential for fast detection of pH at dynamic range.
... Antireflective (AR) coatings are required to improve the light transmission in a wide variety of applications [1][2][3]. The principle of single-layer AR coatings is based on the destructive interference between the air-coating and the coating-substrate interfaces. ...
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.
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