Effect of Surfactants on Stability of Colloidal Sols as Precursors in Sol-Gel Encapsulation

2009 ◽  
Vol 415 ◽  
pp. 57-60 ◽  
Author(s):  
Ioana Lacatusu ◽  
Nicoleta Maria Badea ◽  
Aurelia Meghea
Keyword(s):  
Sol Gel ◽  
Functional Materials ◽  
Flavonoid Compound ◽  
Quaternary Salts ◽  
Bioactive Properties ◽  
Nir Fluorescence ◽  
Scattering Measurements ◽  
Ft Ir ◽  
Preparation Route ◽  
Gel Preparation

This paper aims to study the effect of three alkyl quaternary salts on stability of colloidal sols further used as water-insoluble oligomers for encapsulation of an active flavonoid compound – quercitin. The preparation procedure is described and practical remarks on silica-based sol-gels are included. It is also demonstrated how to exploit the sol-gel preparation route in order to improve the thermal resistance of quercitin and to increase an optical function - fluorescence. The evolution in time of competitive hydrolysis and condensation processes has been observed by dynamic light scattering measurements. The sol-gel materials with entrapped quercitin molecule have been characterised by spectral methods (FT-IR, UV-VIS-NIR), fluorescence and by thermal analysis as well. Sol-gel materials doped with active flavonoid compound may be used in preparation of some functional materials with bioactive properties.

Optical Properties of ATO Sol-gel Coated Carbon Fibers

2012 ◽  
Vol 1454 ◽  
pp. 221-226
Author(s):  
Brandon Richard ◽  
Norma Alcantar ◽  
Andrew Hoff ◽  
Sylvia Thomas
Keyword(s):  
Heat Treatment ◽  
Optical Properties ◽  
Carbon Fibers ◽  
Sol Gel ◽  
Functional Materials ◽  
Additional Material ◽  
Heat Treated ◽  
Ft Ir ◽  
Recent Trends ◽  
Thermal Infrared Radiation

ABSTRACTRecent trends in composite research include the development of structural materials with multiple functionalities. In new studies, novel materials are being designed, developed, modified, and implemented into composite designs. Typically, an increase in functionality requires additional material phases within one system. The presence of excessive phases can result in deterioration of individual or overall properties. True multi-functional materials must maintain all properties at or above the minimum operating limit. In this project, samples of Sb-doped SnO2(ATO) sol-gel solutions are used to coat carbon fibers and are heat treated at a temperature range of 200 – 500 °C. Results from this research are used to model the implementation of sol-gel coatings into carbon fiber reinforced multifunctional composite systems. This research presents a novel thermo-responsive sol-gel/ (dopant) combination and evaluation of the actuating responses due to various heat treatment temperatures. While ATO is a well-known transparent conductive material, the implementation of ATO on carbon fibers for infrared thermal reflectivity has not been examined. These coatings serve as actuators capable of reflecting thermal infrared radiation in mid-range and near-range wavelengths (λ). By altering the ATO sol gel thickness and heat treatment temperatures, optimal optical properties are obtained. While scanning electron microscopy (SEM) is used for imaging, electron diffraction spectroscopy (EDS) is used to verify the compounds present in the coatings. Fourier transform infrared (FT-IR) spectroscopy was performed to analyze the reflectivity in the infrared spectra and analyze the crystal structures after heat treatments.

scholarly journals New SiO2/Caffeic Acid Hybrid Materials: Synthesis, Spectroscopic Characterization, and Bioactivity

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 394 ◽  
Author(s):  
Michelina Catauro ◽  
Federico Barrino ◽  
Giovanni Dal Poggetto ◽  
Giuseppina Crescente ◽  
Simona Piccolella ◽  
...  
Keyword(s):  
Caffeic Acid ◽  
Hybrid Materials ◽  
Structural Changes ◽  
Sol Gel ◽  
Functional Materials ◽  
Spectroscopic Characterization ◽  
Silica Matrix ◽  
Materials Synthesis ◽  
Vis Spectroscopy ◽  
Ft Ir

The sol–gel route represents a valuable technique to obtain functional materials, in which organic and inorganic members are closely connected. Herein, four hybrid materials, containing caffeic acid entrapped in a silica matrix at 5, 10, 15, and 20 wt.%, were synthesized and characterized through Fourier-Transform Infrared (FT-IR) and Ultraviolet-Visible (UV–Vis) spectroscopy. FT-IR analysis was also performed to evaluate the ability to induce the hydroxyapatite nucleation. Despite some structural changes occurring on the phenol molecular skeleton, hybrid materials showed scavenging properties vs. 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and 2,2′-azinobis-(3-ethylbenzothiazolin-6-sulfonic acid) radical cation (ABTS•+), which was dependent on the tested dose and on the caffeic acid wt.%. The SiO2/caffeic acid materials are proposed as valuable antibacterial agents against Escherichia coli and Enterococcus faecalis.

Calcined Powder of the Sol-Gel Synthesis Hydroxyapatite

2013 ◽  
Vol 284-287 ◽  
pp. 41-45
Author(s):  
Chich Kuan Chen
Keyword(s):  
Sol Gel ◽  
Calcium Nitrate ◽  
Molar Ratio ◽  
Sintering Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sintering Time ◽  
Bioactive Properties ◽  
Gel Preparation ◽  
Sol Gel Synthesis

The bioactive properties of hydroxyapatite [HA, Ca10(PO4)6(OH)2] have been demonstrated to be akin to osseous tissue, and provide quick fixation in prosthesis and orthopedics. In this study, sol-gel preparation of hydroxyapatite were arranged for Ca/P=1.67 molar ratio in calcium nitrate [Ca(NO)3.4H2O ] and triethylphosphate [TEP, C6H15PO4] and then dilute in the solvent of ethylene glycol mono-methyl ether [HOCH2CH2OCH3]. Consequently, sintering process was carried out at different temperature for various sintering time to materialize this inorganic polycrystalline phosphate. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) are applied to investigate the as dried amorphous and calcined hydroxyapatite. Results reveal calcinations at 1000oC prolonged for 30 minutes in air can exhibit crystalline hydroxyapatite.

Synthesis and Luminescence Properties of 1,10-Phenanthroline Terbium/Polyvinyl Alcohol Hybrid Functional Materials

2010 ◽  
Vol 663-665 ◽  
pp. 316-319
Author(s):  
Hua Zhang ◽  
Lei Zhou
Keyword(s):  
Polyvinyl Alcohol ◽  
Hybrid Materials ◽  
Hybrid Material ◽  
Fluorescence Spectra ◽  
Photophysical Properties ◽  
Sol Gel ◽  
Functional Materials ◽  
Hybrid Functional ◽  
Separation Processes ◽  
Ft Ir

A series of 1, 10-phenanthroline terbium/ polyvinyl alcohol hybrid materials with different coupling agent contents were prepared by sol-gel method. The morphology and photophysical properties were investigated. FT-IR was applied to characterize the structure of the obtained hybrid material, SEM and fluorescence spectra were applied to characterize the performance of the hybrid material. The result shows that the phase separation processes and the fluorescence quenching were avoided and the optical performance of hybrid materials were improved effectively.

Sol-Gel Preparation of Fe-Doped TiO2 Loaded on HZSM-5 Zeolite

2010 ◽  
Vol 146-147 ◽  
pp. 466-469
Author(s):  
Wen Jie Zhang ◽  
Kuan Ling Wang ◽  
Yang Yu
Keyword(s):  
Supported Catalysts ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
Doped Tio2 ◽  
X Ray ◽  
Photocatalytic Activities ◽  
Ft Ir ◽  
Supported Tio2 ◽  
Gel Preparation ◽  
Scanning Electron

Iron doped TiO2 nanoparticles with different doping amounts were prepared using sol–gel method and characterized. These materials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR). Photocatalytic activities of the supported catalysts were examined for decolorization processes of methyl orange (MO) solution under UV irradiation. The results showed that doping of Fe3+ enhanced the photocatalytic activity of TiO2/HZSM-5, and the optimum Fe3+ doping of Fe/Ti mole ratio for TiO2/HZSM-5 was 0.07%. Doping of Fe3+ did not change the surface morphology of TiO2/HZSM-5. The Fe3+-doped TiO2/HZSM-5 possessed the anatase structures and Ti-O-Si bonds did not form between the HZSM-5 bulk and the supported TiO2.

scholarly journals New SiO2/Caffeic Acid Hybrid Materials: Synthesis, Spectroscopic Characterization and Bioactivity

2019 ◽  
Author(s):  
Michelina Catauro ◽  
Federico Barrino ◽  
Giovanni Dal Poggetto ◽  
Giuseppina Crescente ◽  
Simona Piccolella ◽  
...  
Keyword(s):  
Caffeic Acid ◽  
Hybrid Materials ◽  
Structural Changes ◽  
Sol Gel ◽  
Functional Materials ◽  
Spectroscopic Characterization ◽  
Silica Matrix ◽  
Materials Synthesis ◽  
Vis Spectroscopy ◽  
Ft Ir

Sol-gel route represents a valuable technique to obtain functional materials, in which organic and inorganic members are closely connected. Herein four hybrid materials, containing caffeic acid entrapped in a silica matrix at 5, 10, 15 and 20 wt%, were synthesized and characterized through FT-IR and UV-Vis spectroscopy. FT-IR analysis was also performed to evaluate the ability to induce the hydroxyapatite nucleation. Despite some structural changes occurred on the phenol molecular skeleton, hybrid materials showed scavenging properties vs DPPH and ABTS+ radicals, which was dependent on the tested dose and on the caffeic acid wt%. Finally, the SiO2/caffeic acid materials have been proposed as valuable antibacterial agents against Escherichia coli and Enterococcus faecalis.

Efficient Micromixing for Continuous Biodiesel Production from Jatropha Oil

2018 ◽  
Vol 9 (1) ◽  
pp. 133-139
Author(s):  
Waleed S. Mohammed ◽  
Ahmed H. El-Shazly ◽  
Marwa F. Elkady ◽  
Masahiro Ohshima
Keyword(s):  
Methyl Esters ◽  
Continuous Process ◽  
Sol Gel ◽  
Average Diameter ◽  
Biodiesel Production ◽  
High Mass ◽  
Molar Ratio ◽  
Jatropha Oil ◽  
Energy Deficiency ◽  
Gel Preparation

Introduction: The utilization of biodiesel as an alternative fuel is turning out to be progressively famous these days because of worldwide energy deficiency. The enthusiasm for utilizing Jatropha as a non-edible oil feedstock is quickly developing. The performance of the base catalyzed methanolysis reaction could be improved by a continuous process through a microreactor in view of the high mass transfer coefficient of this technique. Materials & Methods: Nanozirconium tungstovanadate, which was synthetized using sol-gel preparation method, was utilized in a complementary step for biodiesel production process. The prepared material has an average diameter of 0.066 &µm. Results: First, the NaOH catalyzed methanolysis of Jatropha oil was investigated in a continuous microreactor, and the efficient mixing over different mixers and its impact on the biodiesel yield were studied under varied conditions. Second, the effect of adding the nanocatalyst as a second stage was investigated. Conclusion: The maximum percentage of produced methyl esters from Jatropha oil was 98.1% using a methanol/Jatropha oil molar ratio of 11 within 94 s using 1% NaOH at 60 &°C. The same maximum conversion ratio was recorded with the nanocatalyst via only 0.3% NaOH.

scholarly journals Elucidation of the Crystal Growth Characteristics of SnO2 Nanoaggregates Formed by Sequential Low-Temperature Sol-Gel Reaction and Freeze Drying

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1738
Author(s):  
Saeid Vafaei ◽  
Alexander Wolosz ◽  
Catlin Ethridge ◽  
Udo Schnupf ◽  
Nagisa Hattori ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Low Temperature ◽  
Photoelectron Spectroscopy ◽  
High Performance ◽  
Freeze Drying ◽  
Sno2 Nanoparticles ◽  
Sol Gel ◽  
Functional Materials ◽  
Cost Effective ◽  
High Concentration

SnO2 nanoparticles are regarded as attractive, functional materials because of their versatile applications. SnO2 nanoaggregates with single-nanometer-scale lumpy surfaces provide opportunities to enhance hetero-material interfacial areas, leading to the performance improvement of materials and devices. For the first time, we demonstrate that SnO2 nanoaggregates with oxygen vacancies can be produced by a simple, low-temperature sol-gel approach combined with freeze-drying. We characterize the initiation of the low-temperature crystal growth of the obtained SnO2 nanoaggregates using high-resolution transmission electron microscopy (HRTEM). The results indicate that Sn (II) hydroxide precursors are converted into submicrometer-scale nanoaggregates consisting of uniform SnO2 spherical nanocrystals (2~5 nm in size). As the sol-gel reaction time increases, further crystallization is observed through the neighboring particles in a confined part of the aggregates, while the specific surface areas of the SnO2 samples increase concomitantly. In addition, X-ray photoelectron spectroscopy (XPS) measurements suggest that Sn (II) ions exist in the SnO2 samples when the reactions are stopped after a short time or when a relatively high concentration of Sn (II) is involved in the corresponding sol-gel reactions. Understanding this low-temperature growth of 3D SnO2 will provide new avenues for developing and producing high-performance, photofunctional nanomaterials via a cost-effective and scalable method.

scholarly journals Chemical and Structural Characterization of Amorphous and Crystalline Alumina Obtained by Alternative Sol–Gel Preparation Routes

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1761
Author(s):  
Izabela Rutkowska ◽  
Jakub Marchewka ◽  
Piotr Jeleń ◽  
Mateusz Odziomek ◽  
Mateusz Korpyś ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Aluminum Oxide ◽  
Physicochemical Properties ◽  
Sol Gel ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Bet Method ◽  
Gel Preparation ◽  
Angle Spinning ◽  
Middle Infrared

Aluminum oxide is one of the most commonly used materials in the industry. It is used in the field of catalysis, refractories, and optics. Despite the fact that there are many techniques available, there is still a great challenge in obtaining a material with desired and designed properties. Nevertheless, there is a great flexibility in making customized alumina materials with desired physicochemical properties synthesized by sol–gel methods. This work consists in characterizing the physicochemical properties of sol–gel synthesized aluminum oxide using different sol–gel preparation routes. Three different sols were obtained by using organic precursors and underwent thermal treatment. The structure (Middle Infrared Spectroscopy, Diffused Reflectance Infrared Spectroscopy, X-ray Diffraction, Magic Angle Spinning Nuclear Magnetic Resonance) and microstructure (Scanning Electron Microscopy with Electron Dispersive Spectroscopy) tests of the materials were carried out. The specific surface area was determined by using the Brunauer–Emmett–Teller (BET) method. Thermal analysis was performed for all the powders, in order to analyze the specific temperature of materials transformation.

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