Studies of the Initial Steps in Sol-Gel Processing of Si(OR)4:29Si NMR of Alkoxysilane and Alkoxysiloxane Solutions

1986 ◽  
Vol 73 ◽  
Author(s):  
Carol A. Balfe ◽  
Sheryl L. Martinez
Keyword(s):  
Aqueous Solution ◽  
Acid Catalysis ◽  
Chemical Shifts ◽  
Sol Gel ◽  
29Si Nmr ◽  
Methanol Solutions ◽  
Hydrolysis And Condensation ◽  
Silicic Acids ◽  
Starting Solutions ◽  
Gel Processing

ABSTRACTSilicon-29 NMR has been used to investigate the initial steps of hydrolysis and condensation of tetramethoxysilane (TMOS), hexamethoxydisiloxane, and octamethoxytrisiloxane in both basic and acidic methanol solutions. Comparisons of the spectra obtained from the various starting solutions and literature reports of mono-, di-, and tri-silicic acids in aqueous solution were used to identify and assign chemical shifts to condensation intermediates in the TMOS system. The observation of cyclic intermediates in the acid catalysis of TMOS in methanol and the chemical shifts of several products of its hydrolysis and condensation are reported.

Highly effective removal of Cu(II) in aqueous solution by using mesoporous TiO2

2019 ◽  
Vol 80 (5) ◽  
pp. 884-891
Author(s):  
Daying Chen ◽  
Nasi Tu ◽  
Changkun Si ◽  
Meilin Yin ◽  
Xiaohui Wang
Keyword(s):  
Aqueous Solution ◽  
Low Cost ◽  
Sol Gel ◽  
Mesoporous Tio2 ◽  
Adsorption Efficiency ◽  
Batch Experiments ◽  
Order Model ◽  
Effective Removal ◽  
Pseudo Second Order ◽  
Gel Processing

Abstract Mesoporous TiO2 has been prepared by a brief and simple sol–gel processing and applied for the removal of Cu(II) from aqueous solution. The adsorption behavior of mesoporous TiO2 for Cu(II) was investigated using batch experiments. Results showed that the pseudo-second-order model and Langmuir isotherm were more accurate to describe the kinetics process and adsorption isotherm. Mesoporous TiO2 adsorbent displayed excellent Cu(II) adsorption efficiency (195.52mg g−1). The thermodynamic parameters showed that the adsorption was spontaneous and endothermic. It was also found that mesoporous TiO2 could be used at least seven times without obvious loss of its original adsorption efficiency. Therefore, the obtained mesoporous TiO2 could be employed as an effective and low-cost adsorbent for removal of Cu(II) from contaminated effluents.

Non-Hydrolyzed Resins for Organic-Inorganic Hybrid Coatings

2017 ◽  
pp. 771-801 ◽  
Author(s):  
Stefan Holberg
Keyword(s):  
Protective Coatings ◽  
Sol Gel ◽  
Hybrid Coatings ◽  
Industrial Scale ◽  
Atmospheric Moisture ◽  
Inorganic Hybrid ◽  
Chemical Structures ◽  
Hydrolysis And Condensation ◽  
Gel Processing ◽  
Area Of Application

This chapter focuses on resins based on non-hydrolyzed, monomeric and polymeric alkoxysilanes. As alternative to classical sol-gel processing, the resins are applied to a surface without a preceding hydrolysis step. Only after application, hydrolysis and condensation of the alkoxysilyl groups occur by means of atmospheric moisture to result cross-linked organic-inorganic hybrid coatings. While the use of non-hydrolyzed silanes is well established, for example by applying polyethyl silicate as binder for zinc-rich anti-corrosive primers, this chapter describes the chemical structures of various novel organic-inorganic hybrid precursors that have significantly extended the area of application to adhesives and scratch-resistant, repellent, or anti-fouling coatings. At present, individual resins are produced and applied at industrial scale in the fields of protective coatings and automotive topcoats.

Synthesis and Characterization of Ga Doped SiO2 Nanoparticles by a Reverse Micelle and Sol–Gel Processing

2010 ◽  
Vol 11 ◽  
pp. 151-157 ◽  
Author(s):  
Min Yeong Kim ◽  
Min Cheol Chu ◽  
Seong Jai Cho ◽  
Dong Sik Bae
Keyword(s):  
Reverse Micelle ◽  
Sol Gel ◽  
Sio2 Nanoparticles ◽  
Molar Ratio ◽  
Metal Alkoxide ◽  
Hydrolysis And Condensation ◽  
Micro Emulsion ◽  
Average Size ◽  
Gel Processing

Ga doped SiO2 nanosized particles have been synthesized using a reverse micelle technique combined with metal alkoxide hydrolysis and condensation. The size of the particles and the thickness of the coating can be controlled by manipulating the relative rates of the hydrolysis and condensation reactions of tetraethyl orthosilicate(TEOS) within the micro-emulsion. The average size of synthesized Ga doped SiO2 nanoparticles were about in the size range of 10-15 nm and Ga particles 2-5 nm. The effects of synthesis parameters, such as the molar ratio of water to TEOS, and the molar ratio of water to surfactant, are discussed.

Fabrication and Microstructure of ZnO-SiO2 Nanoparticles by a Reverse Micelle and Sol-Gel Processing

2006 ◽  
Vol 510-511 ◽  
pp. 790-793 ◽  
Author(s):  
Rak Hee Kim ◽  
Jae Won Kim ◽  
K.S. Park ◽  
Dong Sik Bae
Keyword(s):  
Reverse Micelle ◽  
Condensation Reaction ◽  
Sol Gel ◽  
Sio2 Nanoparticles ◽  
Molar Ratio ◽  
Metal Alkoxide ◽  
Hydrolysis And Condensation ◽  
Micro Emulsion ◽  
Average Size ◽  
Gel Processing

ZnO-SiO2 nanoparticles were synthesized using a reverse micelle technique combined with metal alkoxide hydrolysis and condensation. The size of the particles was controlled by manipulating the relative rates of the hydrolysis and condensation reaction of tetraethyl orthosilicate (TEOS) within the micro-emulsion. The average size of synthesized ZnO-SiO2 nanoparticles was in the range of 20-40 nm. The effects of synthesis parameters such as the molar ratio of water to precursor and the molar ratio of water to surfactant are discussed.

Fabrication and Microstructure of Ru Core Silica Shell Structure Particles by a Reverse Micelle and Sol-Gel Processing

2017 ◽  
Vol 863 ◽  
pp. 107-111 ◽  
Author(s):  
Son Jeong Hun ◽  
Jeong Ho Sohn ◽  
Dong Sik Bae
Keyword(s):  
Reverse Micelle ◽  
Sol Gel ◽  
Molar Ratio ◽  
Metal Alkoxide ◽  
Diffusion Controlled ◽  
Hydrolysis And Condensation ◽  
Micro Emulsion ◽  
Shell Particles ◽  
Average Size ◽  
Gel Processing

The Ru core SiO2 shell nano size particles have been synthesized within reverse micelle via metal alkoxide hydrolysis and condensation. The size of the particles and the thickness of the coating can be controlled by manipulating the relative rates of the hydrolysis and condensation reactions of tetraethoxysilane (TEOS) within the micro-emulsion. The average size of synthesized Ru core SiO2 shell particles was about in the size range of 15-40 nm. The average size and distribution of the synthesized Ru core SiO2 shell particles increased and narrow with R value increased. Otherwise, the average size and distribution of the synthesized Ru core SiO2 shell particles decreased and narrow with H value increased. TEM studies of particle formation indicate that the reaction process in the complex system containing reverse micelles and TEOS is governed by a diffusion-controlled process. The effects of synthesis parameters, such as the molar ratio of water to TEOS, and the molar ratio of water to surfactant, are discussed.

Non-Hydrolyzed Resins for Organic-Inorganic Hybrid Coatings

2016 ◽  
pp. 105-135
Author(s):  
Stefan Holberg
Keyword(s):  
Protective Coatings ◽  
Sol Gel ◽  
Hybrid Coatings ◽  
Industrial Scale ◽  
Atmospheric Moisture ◽  
Inorganic Hybrid ◽  
Chemical Structures ◽  
Hydrolysis And Condensation ◽  
Gel Processing ◽  
Area Of Application

This chapter focuses on resins based on non-hydrolyzed, monomeric and polymeric alkoxysilanes. As alternative to classical sol-gel processing, the resins are applied to a surface without a preceding hydrolysis step. Only after application, hydrolysis and condensation of the alkoxysilyl groups occur by means of atmospheric moisture to result cross-linked organic-inorganic hybrid coatings. While the use of non-hydrolyzed silanes is well established, for example by applying polyethyl silicate as binder for zinc-rich anti-corrosive primers, this chapter describes the chemical structures of various novel organic-inorganic hybrid precursors that have significantly extended the area of application to adhesives and scratch-resistant, repellent, or anti-fouling coatings. At present, individual resins are produced and applied at industrial scale in the fields of protective coatings and automotive topcoats.

The Role of Chemical Additives in Sol-Gel Processing

1986 ◽  
Vol 73 ◽  
Author(s):  
L. L. Hench ◽  
G. Orcel ◽  
J. L. Nogues
Keyword(s):  
Chemical Reactions ◽  
Acid Catalysis ◽  
Structural Model ◽  
Sol Gel ◽  
Silica Sol ◽  
Chemical Additives ◽  
Solubility Test ◽  
Acid Solubility ◽  
Gel Processing

ABSTRACTThe effect of various concentrations of formamide with and without acid catalysis on TMOS derived silica sol and gel structures and physical properties is described using a quantitative structural model. The model is based upon 29Si NMR, SAXS, Raman and FTIR spectroscopy, and an acid solubility test. Changes in chemical reactions during drying due to formamide are presented using FTIR, DSC and TGA data.

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