Sol-Gel Processing Using Aminofunctional Silanes

1994 ◽  
Vol 346 ◽  
Author(s):  
Wanqing Cao ◽  
Arlon J. Hunt
Keyword(s):  
Light Scattering ◽  
Sol Gel ◽  
Gel Formation ◽  
Fluoride Ions ◽  
Homogeneous Microstructure ◽  
Acid Catalyzed ◽  
Gel Processing

ABSTRACTClear gels have been made from TEOS and the aminofunctional silane under acid-catalyzed conditions and light scattering of the gels has been related to pH and the concentration of fluoride ions in the sol as well as the amount of the aminosilane used. We have succeeded in preparing a series of gels containing Ni2+ or Cu2+ ions immobilized by chelation either before or after the gel formation. Aerogels made from these gels in particular, doped by the method of impregnation, have had a homogeneous microstructure on the scale of only a few nanometers.

Hafnium Metallo-Organic Films and Gels Produced by Sol-Gel Processing

1989 ◽  
Vol 155 ◽  
Author(s):  
Charles D. Gagliardi ◽  
Kris A. Berglund
Keyword(s):  
Light Scattering ◽  
Sol Gel ◽  
Organic Films ◽  
Spin Casting ◽  
Synthesis Technique ◽  
Refractory Oxides ◽  
Sol Gel Process ◽  
Optically Transparent ◽  
Acid Catalyzed ◽  
Gel Processing

ABSTRACTMetallo-organic materials are often used as precursors for highly refractory oxides and hightemperature composites. The feasibility of producing hafnium metallo-organic films and gels by sol-gel techniques is demonstrated in the present study. Since hafnium alkoxides are not commercially available, their preparation is an obstacle in the development of their sol-gel processing applications. A common synthesis technique was used to produce hafnium isopropoxide, which was subsequently hydrolyzed under acid catalyzed conditions to produce films and gels. The films were prepared by spin casting and remained optically transparent. Initially, the gels were also optically transparent, but became translucent upon drying. Raman, IR, and light scattering spectroscopies were used to characterize this sol-gel process, and it is compared with the analogous processing of titanium and zirconium alkoxides.

Physical Properties of Dried Na2O-SiO2 Monoliths

1988 ◽  
Vol 121 ◽  
Author(s):  
Rounan Li ◽  
L. L. Hench
Keyword(s):  
Optical Properties ◽  
Physical Properties ◽  
Bulk Density ◽  
Sol Gel ◽  
Index Of Refraction ◽  
True Density ◽  
Compositional Dependence ◽  
Ir Reflection ◽  
Acid Catalyzed ◽  
Gel Processing

ABSTRACTDried monolithic gels of compositions XNa2O-(1-X)SiO2 (with X from 0 mol% to 7 mol%) were obtained by acid catalyzed sol-gel processing using tetramethylorthosilicate and NaNO3. Optically clear monoliths in the range of 20 to 90 mm diameter by 3 to 20 mm thickness were routinely produced by controlling the processing schedule. Complete drying in air without cracking was achieved at 180°C from 10–14 days. The bulk density and optical properties of the gels, characterized by UV/VIS/NIR transmission, IR reflection and index of refraction, showed a compositional dependence on Na2O similar to melt glasses of the same Na2O content. However, the true density and microhardness decreased with Na2O content in contrast to melt glasses.

Investigation of the Effect of Dimethylformamide Addition on Alumina Sol-Gel Formation by 27Al NMR and Rheology Measurements

1988 ◽  
Vol 121 ◽  
Author(s):  
L. F. Nazar ◽  
L. C. Klein ◽  
D. Napier
Keyword(s):  
Room Temperature ◽  
Sol Gel ◽  
Gel Formation ◽  
27Al Nmr ◽  
Rapid Decay ◽  
Similar Treatment ◽  
High Acid ◽  
Alumina Sol ◽  
Gel Processing

ABSTRACTThe role of dimethylformamide (DMF) in the sol-gel processing of alumina at high acid/Al ratios was studied at different hydrolysis and aging temperatures by 27A1 NMR and rheology measurements. The composition of sols in which aluminum sec-butoxide was hydrolyzed in 50/50 mixtures of DMF and H2O was similar to those hydrolyzed without DMF, although the DMF sols contained a slightly lower concentration of mobile alumina species. The Al13O4 (OH)24(H2O)127+ cation predominated in both DMF and aqueous sols hydrolyzed at room temperatures at acid/Al ratios between 0.4 and 0.6. However, aging the room temperature DMF sols at 90°C for 24 hrs was found to cause rapid gelation whereas a similar treatment of the aqueous sols resulted in a decrease in viscosity. This gelation process was correlated with a more rapid decay of the Al13 and A1(H2O)63+ cations in the DMF sols. In contrast, DMF sols hydrolyzed at 90°C were found to be less viscous than their aqueous counterparts at high acid ratios.

Solvent Quality Effects in Sol-Gel Processing

1992 ◽  
Vol 271 ◽  
Author(s):  
Joseph K. Bailey
Keyword(s):  
Molecular Weight ◽  
Light Scattering ◽  
Solubility Parameter ◽  
Sol Gel ◽  
Parameter Range ◽  
Molecular Weights ◽  
Solvent Quality ◽  
Silicon Alkoxides ◽  
Gel Processing

ABSTRACTTo understand how solvent quality can be used to tailor structure in sol-gel processing of silicon alkoxides, polymerized tetramethoxysilane polymers were synthesized and fractionated to give relatively stable, narrow molecular weight dispersion samples. These polymers had molecular weights ranging from 8000 to 45,000. The solubility parameter range for these polymers is 8.9–14.5 (cal/cm3)1/2. Light scattering confirmed that this range could be used to predict solvent quality. Bulk gels prepared using good versus poor solvents demonstrated that solvent quality can be used to tailor properties of the gels, presumably by modifying the extent of interpenetration of the growing polymers.

scholarly journals Mesoporous adsorbent for competitive adsorption of fluoride ions in zinc sulfate solution

RSC Advances ◽  
2021 ◽  
Vol 11 (22) ◽  
pp. 13521-13529
Author(s):  
Lisi Liang ◽  
Jiayu Mi ◽  
Linbo Li ◽  
Xihong He ◽  
Wenlong Guo
Keyword(s):  
Zinc Sulfate ◽  
Competitive Adsorption ◽  
Sol Gel ◽  
Sulfate Solution ◽  
Fluoride Ions ◽  
Zinc Sulfate Solution ◽  
Adsorption Performance ◽  
Mesoporous Adsorbent ◽  
Sol Gel Process ◽  
Acid Catalyzed

Al–La hybrid gel was prepared using an innovative acid-catalyzed and calcination free sol–gel process, and showed excellent adsorption performance for fluoride ions in zinc sulfate solution.

Preparation of graft copolymers by the reaction of polymeric acyl chlorides with monohydroxy-terminated polymers: An introductory study

1988 ◽  
Vol 53 (8) ◽  
pp. 1735-1744 ◽  
Author(s):  
Jitka Horská ◽  
Jaroslav Stejskal ◽  
Pavel Kratochvíl ◽  
Aubrey D. Jenkins ◽  
Eugenia Tsartolia ◽  
...  
Keyword(s):  
Light Scattering ◽  
Chemical Composition ◽  
Statistical Model ◽  
Graft Copolymers ◽  
Coupling Reaction ◽  
Molecular Characteristics ◽  
Gel Formation ◽  
Acyl Chlorides ◽  
Molecular Weights

An attempt was made to prepare well-defined graft copolymers by the coupling reaction between acyl chloride groups located along the backbone chain and monohydroxy-terminated grafts prepared separately. The molecular weights and the parameters of heterogeneity in chemical composition of the products were determined by light scattering and osmometry. The determination of molecular characteristics revealed that the degree of grafting was low. The results therefore could not be confronted with a statistical model at this stage. The problems encountered in the synthesis, e.g., gel formation, and the data relating to the soluble products are discussed.

Synthesis and characterization of BaMgAl10O17:Eu phosphors derived by sol–gel processing

2002 ◽  
Vol 126 (2) ◽  
pp. 161-165 ◽  
Author(s):  
Junying Zhang ◽  
Zhongtai Zhang ◽  
Zilong Tang ◽  
Zishan Zheng ◽  
Yuanhua Lin
Keyword(s):  
Sol Gel ◽  
Synthesis And Characterization ◽  
Gel Processing

Chemical Solution Deposition of Lanthanum Zirconate Buffer Layers on Biaxially Textured Ni–1.7% Fe–3% W Alloy Substrates for Coated-conductor Fabrication

2002 ◽  
Vol 17 (6) ◽  
pp. 1543-1549 ◽  
Author(s):  
S. Sathyamurthy ◽  
M. Paranthaman ◽  
T. Aytug ◽  
B. W. Kang ◽  
P. M. Martin ◽  
...  
Keyword(s):  
Sol Gel ◽  
Rf Sputtering ◽  
Cube Texture ◽  
Dip Coating ◽  
Buffer Layers ◽  
Lanthanum Zirconate ◽  
Solution Deposition ◽  
Ybco Films ◽  
Current Densities ◽  
Gel Processing

Sol-gel processing of La2Zr2O7 (LZO) buffer layers on biaxially textured Ni–1.7% Fe–3% W alloy substrates using a continuous reel-to-reel dip-coating unit has been studied. The epitaxial LZO films obtained have a strong cube texture and uniform microstructure. The effects of increasing the annealing speed on the texture, microstructure, and carbon content retained in the film were studied. On top of the LZO films, epitaxial layers of yttria-stabilized zirconia and Ceria (CeO2) were deposited using rf sputtering, and YBa2Cu3Ox (YBCO) films were then deposited using pulsed laser deposition. Critical current densities (Jc) of 1.9 MA/cm2 at 77 K and self-field and 0.34 MA/cm2at 77 K and 0.5 T have been obtained on these films. These values are comparable to those obtained on YBCO films deposited on all-vacuum deposited buffer layers and the highest ever obtained using solution seed layers.

Effect of acetylacetone on the preparation of PZT materials in sol–gel processing

2002 ◽  
Vol 96 (3) ◽  
pp. 307-312 ◽  
Author(s):  
Luqian Weng ◽  
Xujin Bao ◽  
Kwesi Sagoe-Crentsil
Keyword(s):  
Sol Gel ◽  
Gel Processing
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