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Special Issue "Sol-Gel-Derived Materials"

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Materials Chemistry".

Deadline for manuscript submissions: closed (19 November 2021) | Viewed by 4169

Special Issue Editor

Prof. Bruno Capoen
E-Mail Website
Guest Editor
University of Lille, Villeneuve-d'Ascq, France
Interests: silica glasses; fiber preforms; emission spectroscopy; radiation dosimetry

Special Issue Information

Dear Colleagues,

Since the beginning of the 1990s, sol–gel technology has attracted a research community working in all the facets of materials sciences, including optics, electronics, catalysis, mechanics, pharmacy, and medicine. Hence, in these few decades, advanced sol–gel processes have enabled the preparation of new functional materials, even those unreachable through other technologies.

First of all, the passage through a controllable porous state is at the origin of important advantages of sol–gel materials. The porous texture and large surface areas associated with aerogels, and even xerogels, has been essential to the development of catalysts, to the control of the entrapment and release of drugs or biomolecules, and for obtaining homogeneously doped glasses that are usable in fiber optics devices. Second, the polymeric nature of the chemical bonds involved in the gelation transitions allows the association, at low temperature, of organic and inorganic species that can be combined in hybrid materials. Moreover, progress in the chemistry of metal alkoxide precursors makes it possible to produce high-purity materials that radically improve the optical quality of sol–gel-derived glasses and ceramics, for example.

Of course, sol–gel processes are now used to obtain different shapes of advanced materials, such as powders, thin films, fibers, porous monoliths, dense glasses, or ceramics for a wide range of applications. Furthermore, new potential applications are continuously emerging in all of these domains. I kindly invite you to submit a manuscript for this Special Issue, which is devoted to the development of sol–gel materials and to their applications in various areas. Full papers, communications, and reviews are all welcome.

Prof. Bruno Capoen
Guest Editor

Manuscript Submission Information

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2300 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • sol–gel material
  • applications
  • thin films
  • powders
  • fibers
  • glass
  • ceramics

Published Papers (4 papers)

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Research

Article
Development of Efficient One-Pot Methods for the Synthesis of Luminescent Dyes and Sol–Gel Hybrid Materials
Materials 2022, 15(1), 203; https://doi.org/10.3390/ma15010203 - 28 Dec 2021
Cited by 1 | Viewed by 645
Abstract
This paper presents a comparison of the simultaneous preparation of di-O-alkylated and ether–ester derivatives of fluorescein using different methods (conventional or microwave heating). Shortening of the reaction time and increased efficiency were observed when using a microwave reactor. Moreover, described here [...] Read more.
This paper presents a comparison of the simultaneous preparation of di-O-alkylated and ether–ester derivatives of fluorescein using different methods (conventional or microwave heating). Shortening of the reaction time and increased efficiency were observed when using a microwave reactor. Moreover, described here for the first time is the application of a fast, simple, and eco-friendly ball-assisted method to exclusively obtain ether–ester derivatives. We also demonstrate that fluorescein can be effectively functionalized by O-alkylation carried out under microwave or ball-milling conditions, saving time and energy and affording the desired products with good yields and minimal byproduct formation. All the synthesized products as well as pH-dependent (prototropic) forms trapped in the SiO2 matrix were examined using UV–Vis and fluorescence spectroscopy. Full article
(This article belongs to the Special Issue Sol-Gel-Derived Materials)
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Article
Silica and Silica–Titania Xerogels Doped with Iron(III) for Total Antioxidant Capacity Determination
Materials 2021, 14(8), 2019; https://doi.org/10.3390/ma14082019 - 17 Apr 2021
Cited by 2 | Viewed by 671
Abstract
In order to design a sensor material for total antioxidant capacity determination we have prepared silica and silica–titania xerogels doped with iron(III) and modified with 1,10-phenanthroline. Titanium(IV) tetraethoxyde content in the precursors (titanium(IV) tetraethoxyde and tetraethyl orthosilicate) mixtures has been varied from 0 [...] Read more.
In order to design a sensor material for total antioxidant capacity determination we have prepared silica and silica–titania xerogels doped with iron(III) and modified with 1,10-phenanthroline. Titanium(IV) tetraethoxyde content in the precursors (titanium(IV) tetraethoxyde and tetraethyl orthosilicate) mixtures has been varied from 0 to 12.5% vol. Iron(III) concentrations in sol has been varied from 1 to 100 mM. The increase of titanium(IV) content has led to a decrease in BET surface area and average pore diameter and an increase of micropore surface area and volume, which has resulted in better iron(III) retention in the xerogels. Iron(III), immobilized in the xerogel matrix, retains its ability to form complexes with 1,10-phenanthroline and to be reduced to iron(II). Static capacities for 1,10-phenanthroline have been determined for all the iron(III) doped xerogels (0.207 mmol/g–0.239 mmol/g) and they are not dependent on the iron(III) content. Sensor materials—xerogels doped with iron(III) and modified with 1,10-phenanthroline—have been used for antioxidants (catechol, gallic and ascorbic acids, and sulphite) solid phase spectrophotometric determination. Limits of detection for catechol, gallic and ascorbic acids, and sulphite equal 7.8 × 10−6 M, 5.4 × 10−6 M, 1.2 × 10−5 M, and 3.1 × 10−4 M, respectively. The increase of titanium(IV) content in sensor material has led to an increase of the reaction rate and the sensitivity of determination. Proposed sensor materials have been applied for total antioxidant capacity (in gallic acid equivalents) determination in soft beverages, have demonstrated high stability, and can be stored up to 6 months at room temperature. Full article
(This article belongs to the Special Issue Sol-Gel-Derived Materials)
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Article
Comparison between the UV and X-ray Photosensitivities of Hybrid TiO2-SiO2 Thin Layers
Materials 2020, 13(17), 3730; https://doi.org/10.3390/ma13173730 - 24 Aug 2020
Cited by 3 | Viewed by 947
Abstract
The photo-induced effects on sol–gel-based organo TiO2-SiO2 thin layers deposited by the dip-coating technique have been investigated using two very different light sources: A light-emitting diode (LED) emitting in the UV (at 365 nm, 3.4 eV) and an X-ray tube [...] Read more.
The photo-induced effects on sol–gel-based organo TiO2-SiO2 thin layers deposited by the dip-coating technique have been investigated using two very different light sources: A light-emitting diode (LED) emitting in the UV (at 365 nm, 3.4 eV) and an X-ray tube producing 40 keV mean-energy photons. The impact of adding a photo-initiator (2,2-dimethoxy-2-phenylacetophenone-DMPA) on the sol–gel photosensitivity is characterized namely in terms of the photo-induced refractive index measured through M-line spectroscopy. Results show that both silica-titania sol–gel films with or without the photo-initiator are photosensitive to both photon sources. The induced refractive index values reveal several features where slightly higher refractive indexes are obtained for the sol–gel containing the photo-initiator. UV and X-ray-induced polymerization degrees are discussed using Fourier-transform infrared (FTIR) spectroscopy where the densification of hybrid TiO2-SiO2 layers is related to the consumption of the CH=C groups and to the decomposition of Si-OH and Si-O-CH3 bonds. X-rays are more efficient at densifying the TiO2-SiO2 inorganic and organic network with respect to the UV photons. Hard X-ray photolithography, where no cracks or damages are observed after intense exposition, can be a promising technique to design submicronic-structure patterns on TiO2-SiO2 thin layers for the building of optical sensors. Full article
(This article belongs to the Special Issue Sol-Gel-Derived Materials)
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Article
Cu/Ce-co-Doped Silica Glass as Radioluminescent Material for Ionizing Radiation Dosimetry
Materials 2020, 13(11), 2611; https://doi.org/10.3390/ma13112611 - 08 Jun 2020
Cited by 6 | Viewed by 1198
Abstract
Optically activated glasses are essential to the development of new radiation detection systems. In this study, a bulk glassy rod co-doped with Cu and Ce ions, was prepared via the sol-gel technique and was drawn at about 2000 °C into a cylindrical capillary [...] Read more.
Optically activated glasses are essential to the development of new radiation detection systems. In this study, a bulk glassy rod co-doped with Cu and Ce ions, was prepared via the sol-gel technique and was drawn at about 2000 °C into a cylindrical capillary rod to evaluate its optical and radioluminescence properties. The sample showed optical absorption and photoluminescence (PL) bands attributed to Cu+ and Ce3+ ions. The presence of these two ions inside the host silica glass matrix was also confirmed using PL kinetics measurements. The X-ray dose rate was remotely monitored via the radioluminescence (RL) signal emitted by the Cu/Ce scintillating sensor. In order to transport the optical signal from the irradiation zone to the detection located in the instrumentation zone, an optical transport fiber was spliced to the sample under test. This RL signal exhibited a linear behavior regarding the dose rate in the range at least between 1.1 mGy(SiO2)/s and 34 Gy(SiO2)/s. In addition, a spectroscopic analysis of this RL signal at different dose rates revealed that the same energy levels attributed to Cu+ and Ce3+ ions are involved in both the RL mechanism and the PL phenomenon. Moreover, integrated intensities of the RL sub-bands related to both Cu+ and Ce3+ ions depend linearly on the dose rate at least in the investigated range from 102 mGy(SiO2)/s up to 4725 mGy(SiO2)/s. The presence of Ce3+ ions also reduces the formation of HC1 color centers after X-ray irradiation. Full article
(This article belongs to the Special Issue Sol-Gel-Derived Materials)
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