scholarly journals Heterogeneous Hybrid Nanocomposite Based on Chitosan/Magnesia Hybrid Films: Ecofriendly and Recyclable Solid Catalysts for Organic Reactions

Polymers ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 3583
Author(s):  
Metwally Madkour ◽  
Khaled D. Khalil ◽  
Fakhreia A. Al-Sagheer
Keyword(s):  
Heterogeneous Catalysts ◽  
Sol Gel ◽  
Analytical Techniques ◽  
Hybrid Films ◽  
One Pot ◽  
Solid Catalysts ◽  
Force Microscopy ◽  
Chitosan Matrix ◽  
Atomic Force ◽  
Sol Gel Process

Chitosan/magnesia hybrid films (CS-Mg) have been prepared via sol-gel process and employed as heterogeneous catalysts. An in situ generation of a magnesia network in the chitosan matrix was performed through hydrolysis/condensation reactions of magnesium ethoxide. The synthesized hybrid films were characterized using various analytical techniques, such as X-ray photo-electron spectroscopy (XPS), field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). The hybrid films display excellent catalytic activities in Michael and Knoevenagel reactions via one pot or solvent-free approaches under microwave irradiation conditions. Chitosan/magnesia hybrid films, catalysed pyrimidine, benzochromene, coumarin and arylidene-malononitriles derivatives formation reactions occurred with highly efficient yields of 97%, 92%, 86% and 95% respectively. Due to the fact that the films are durable and insoluble in common organic solvents, they were easily separated and can be recycled up to five times without a considerable loss of their catalytic activity.

Infrared Characterization of PMMA-SiO2 Hybrid Glasses Obtained by Sol-Gel Process

2010 ◽  
Vol 1278 ◽  
Author(s):  
L.L. Díaz-Flores ◽  
A. S. López Rodríguez ◽  
P. SifuentesGallardo ◽  
M.A. Hernàndez Rivera ◽  
M.a Garnica Romo ◽  
...  
Keyword(s):  
Sol Gel ◽  
Chemical Properties ◽  
Hybrid Coatings ◽  
Force Microscopy ◽  
Air Atmosphere ◽  
Atomic Force ◽  
Sol Gel Process ◽  
Traditional Process ◽  
And Chemical Properties

AbstractThis work is about the production of hybrid coatings of the system SiO2-PMMA (PMMA, polymethylmethacrylate). These materials have interesting mechanical and chemical properties useful for anticorrosive and wear resistance applications. SiO2-PMMA hybrids were obtained by the sol-gel traditional process, using tetraethylorthosilicate (TEOS) and methylmethacrylate (MMA) by Aldrich Co, as starting reagents. The SiO2:PMMA ratio was varied from 0:1 to about 1:1 at air atmosphere deposition. The coatings were obtained on acrylic sheets and silicon wafers. A diversity of coatings with chemical composition ranging from SiO2 and PMMA to obtain the SiO2-PMMA hybrids were obtained. Infrared (IR) and atomic force microscopy (AFM), were performed to determinate structural and morphological behavior.

scholarly journals Synthesis and Characterization of Modified Cellulose Acetate Propionate Nanocomposites via Sol-Gel Process

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Patrycja Wojciechowska ◽  
Zenon Foltynowicz ◽  
Marek Nowicki
Keyword(s):  
Cellulose Acetate ◽  
Sol Gel ◽  
Hybrid Nanocomposites ◽  
Organic Polymer ◽  
Nmr Studies ◽  
Force Microscopy ◽  
Atomic Force ◽  
Cellulose Acetate Propionate ◽  
Sol Gel Process ◽  
Modified Cellulose

In this study novel organic-inorganic hybrid nanocomposites were synthesized from modified cellulose acetate propionate (MCAP) via sol-gel reaction at ambient temperature. The inorganic phase was introduced in situ by hydrolysis-condensation of tetraethoxysilane (TEOS) in different concentrations, under acid catalysis, in the presence of organic polymer dissolved in acetone. The chemical modification of CAP was monitored by infrared spectroscopy (IR). The nanocomposites structure was characterized by IR analysis and solid state29Si NMR studies. The spectral data revealed that organic and inorganic phases are linked through covalent bound. Surface morphology of the samples and the degree of dispersion of inorganic phase in the polymer matrix were investigated using atomic force microscopy (AFM) and scanning electron microscopy (SEM). The actual incorporation of the inorganic component into the hybrid nanocomposites was deducted from the residual weight according to thermogravimetric analysis (TGA).

scholarly journals Preparation of (Pb,Ba)TiO3 powders and highly oriented thin films by a sol-gel process

2004 ◽  
Vol 19 (5) ◽  
pp. 1492-1498 ◽  
Author(s):  
Stacey W. Boland ◽  
Suresh C. Pillai ◽  
Wein-Duo Yang ◽  
Sossina M. Haile
Keyword(s):  
Thin Films ◽  
Sol Gel ◽  
Chelating Agent ◽  
Titanium Isopropoxide ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Force Microscopy ◽  
Molar Ratios ◽  
Atomic Force ◽  
Sol Gel Process

Solid solution Pb1-xBaxTiO3, with particular emphasis on Pb0.5Ba0.5TiO3, was prepared using a sol-gel process incorporating lead acetate trihydrate, barium acetate, and titanium isopropoxide as precursors, acetylacetone (2,4 pentanedione) as a chelating agent, and ethylene glycol as a solvent. The synthesis procedure was optimized by systematically varying acetylacetone: Ti and H2O:Ti molar ratios and calcination temperature. The resulting effects on sol and powder properties were studied using thermogravimetric analysis/differential scanning calorimetry, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller analysis, and x-ray diffraction (XRD). Crystallization of the perovskite structure occurred at a temperature as low as 450 °C. Thin films were prepared by spin coating on (100) MgO. Pyrolysis temperature and heating rate were varied, and the resultant film properties investigated using field-emission scanning electron microscopy, atomic force microscopy, and XRD. Under optimized conditions, highly oriented films were obtained at a crystallization temperature of 600 °C.

Anatase TiO2 Films via a Sol-Gel and Hydrothermal Crystallization for Enhanced Corrosion Resistance

2011 ◽  
Vol 356-360 ◽  
pp. 2707-2710 ◽  
Author(s):  
Hong Yun ◽  
Chang Jian Lin ◽  
Qun Jie Xu
Keyword(s):  
Corrosion Resistance ◽  
Hydrothermal Treatment ◽  
316L Stainless Steel ◽  
Electrochemical Impedance ◽  
Sol Gel ◽  
Metallic Substrates ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Sol Gel Process

Anatase of TiO2films were supplied on the surface of 316L stainless steel by a sol–gel process followed by hydrothermal treatment in water. The as-prepared samples were characterized with filed emission scanning electron microscope (FESEM), transmission electron microscopy (TEM), atomic force microscopy (AFM) and Raman spectroscopy. The corrosion performances of the films in 3.5 wt% NaCl solution were evaluated by electrochemical impedance spectroscopy (EIS) and polarization measurements. The results revealed that the corrosion resistance of the TiO2films via the hydrothermal treatment at 170°C for 4h exceeded that of the counterparts treated by conventional calcination at 450°C. This could be attributed that the surface of such a sample was more compact and uniform, relatively well-crystallized, able to act as an optimal barrier layer to metallic substrates.

Comparison between the optical and surface properties of TiO2 and Ag/TiO2 thin films prepared by sol-gel process

2011 ◽  
Vol 1352 ◽  
Author(s):  
Marcelo M. Viana ◽  
Nelcy D. S. Mohallem
Keyword(s):  
Thin Films ◽  
Sol Gel ◽  
Refraction Index ◽  
Titanium Isopropoxide ◽  
X Ray Diffraction ◽  
Tio2 Thin Films ◽  
Force Microscopy ◽  
Atomic Force ◽  
Vis Spectroscopy ◽  
Sol Gel Process

ABSTRACTColloidal precursor solutions, obtained from a mixture of titanium isopropoxide, isopropyl alcohol and silver nitrate, were used to fabricate amorphous TiO2 and Ag/TiO2 thin films by sol-gel process. The films were deposited on borosilicate substrates, which were heated at 400 °C for 30 minutes and cooled rapidly to the formation of amorphous coatings. The films were investigated by X-ray diffraction, scanning electron microscopy, atomic force microscopy and UV-vis spectroscopy. The thickness, roughness, refraction index, and particle size of the TiO2 and Ag/TiO2 films were determined and compared. Finally, hydrophobic-hydrophilic property was evaluated to the thin films produced.

Microstructure and Optical Properties of (Zr0.8, Sn0.2)TiO4 Thin Films Grown on Si(100) Substrates by a Sol-Gel Process

2005 ◽  
Vol 475-479 ◽  
pp. 3693-3696
Author(s):  
Wen Xiu Cheng ◽  
Ai Li Ding ◽  
Ping Sun Qiu
Keyword(s):  
Thin Films ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
Indirect Transition ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Sol Gel Process ◽  
Surface Morphologies ◽  
Transition Type

Amorphous and crystalline (Zr0.8,Sn0.2)TiO4 （ZST） thin films deposited on Si(100) substrates have been prepared by a sol-gel process. The crystal structure and surface morphologies of the thin films have been studied by X-ray diffraction and atomic force microscopy. The crystalline ZST films on Si(100) substrata with a (111) orientation The refractive index n and extinction coefficient k of the amorphous and crystalline thin films were obtained by spectroscopy ellipsometry as a function of phone energy in the range from 0.7 to 5.4 eV. The absorption edges for amorphous and crystalline ZST are 3.83 and 3.51eV of indirect–transition type respectively.

scholarly journals Sol-gel synthesis and study of neodymium substitution effects in Co-Al-Nd-O system with possible applications as novel inorganic pigments

2012 ◽  
Vol 10 (5) ◽  
pp. 1574-1583 ◽  
Author(s):  
Dalia Jonynaite ◽  
Darius Jasaitis ◽  
Rimantas Raudonis ◽  
Algirdas Selskis ◽  
Remigijus Juskenas ◽  
...  
Keyword(s):  
Sol Gel ◽  
Substitution Effects ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Sol Gel Process ◽  
New Compounds ◽  
Sol Gel Synthesis

AbstractIn the present work, the formation of cobalt aluminium spinel (CoAl2O4) as well as novel cobalt neodymium-aluminates with nominal compositions of CoAl1.75Nd0.25O4, CoAl1.5Nd0.5O4 and CoAlNdO4 by an aqueous sol-gel process and the sinterability of the products are investigated. The metal ions, generated by dissolving starting materials of metals in the diluted acetic acid were complexed by 1,2-ethanediol to obtain the precursors for the mixed metal ceramics. The phase purity of the synthesized compounds was characterized by powder X-ray diffraction analysis and infrared spectroscopy. The microstructural evolution and morphological features of the products were studied by scanning electron microscopy and atomic force microscopy, which together with the optical characterization of these new compounds showed that the sol-gel-derived materials could be successfully used as effective cobalt-based ceramic pigments.

Nano Composite Membranes of Sulfonated Poly (Ether Ketone)/ Poly (Ether Sulfone) Copolymer and SiO2 for Fuel Cell Application

2007 ◽  
Vol 544-545 ◽  
pp. 1013-1016
Author(s):  
Hae Suck Park ◽  
Dong Hwan Suh ◽  
Dong Hun Lee ◽  
Whan Gi Kim
Keyword(s):  
Sol Gel ◽  
Chemical Properties ◽  
Composite Membranes ◽  
Scanning Calorimetry ◽  
Nano Composite ◽  
Force Microscopy ◽  
Atomic Force ◽  
Fuel Cell Application ◽  
Sol Gel Process ◽  
Ether Ketone

Novel bisphenol-based wholly aromatic poly(ether ketone)/poly(ether sulfone) copolymers containing pendant sulfonate groups were prepared by direct aromatic nucleophilic substitution polycondensation of 4,4-difluoro-3,3’-disodiumsulfonylbenzophenone (40mol% of bisphenol), difluorophenylsulfone and bisphenol A. Organic-inorganic composite membranes were obtained by mixing organic polymers with hydrophilic SiO2 (ca. 20nm) obtained by sol-gel process. The physic-chemical properties of these composite membranes were studied by thermogravimetry analysis(TGA), differential scanning calorimetry (DSC) and transform infrared(FTIR) spectroscopy. Scanning electron microscopy (SEM) and atomic Force microscopy (AFM) were used to observe the surface of membrances. The proton conductivity as a function of temperature decreased as SiO2 content increased, but water uptake increased. The membranes were shown all requisite properties; IEC (1.5meq./g), thermal stablity (Tg= 185°C), and low affinity towards methanol (1.5x10-7 - 4.3x10-7 cm2/S).

Microstructural Evolution of Titania Sol-Gel Thin Films

1994 ◽  
Vol 346 ◽  
Author(s):  
Yongan Yan ◽  
S. Ray Chaudhuri ◽  
Din-Guo Chen ◽  
Barry Bolker ◽  
Arnab Sarkar
Keyword(s):  
Thin Films ◽  
Anatase Phase ◽  
Sol Gel ◽  
Structural Evolution ◽  
Dip Coating ◽  
Force Microscopy ◽  
Grain Sizes ◽  
Atomic Force ◽  
Sol Gel Process ◽  
Titania Sol

ABSTRACTThin films of crystalline titania with different grain sizes and porosities were prepared by dip-coating on Si (100) substrates starting from a sol-gel process. Three synthesis procedures were developed and compared, using acetylacetone (acac, with HCI) and acetic acid (HOAc) as modifying agents or directly using hydrochloric acid as catalyst. The structural evolution of the films was characterized by Glazing Angle X-ray Diffraction (XRD), Spectroscopic Ellipsometry and Atomic Force Microscopy (AFM). Anatase phase was observed on all of the films calcined at 440° C. The grain sizes and crystallinity generally increased with calcination temperature. Thin films obtained from acac- and HOAc-modified titanium sols had fine grains (50–80 nm) and less porosity (<10%) after calcination at 1000° C. Thin films derived from the sol catalyzed directly with acid had the largest grains (90–130 nm), higher crystallinity and greater porosity (17%).

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