Photochromism of spiropyran and diarylethenedoped silica gels prepared by the sol-gel process

1995 ◽  
Vol 30 (22) ◽  
pp. 5789-5792 ◽  
Author(s):  
M. Nogami ◽  
Y. Abe
Keyword(s):  
Sol Gel ◽  
Silica Gels ◽  
Sol Gel Process

Preparation of Silica Aerogels Monoliths from Hydrophobic Silica Gels and Pluronic10R5 via Sol–Gel Process

2020 ◽  
Vol 12 (2) ◽  
pp. 206-211
Author(s):  
Supattra Eangpayung ◽  
Supan Yodyingyong ◽  
Darapond Triampo
Keyword(s):  
Mass Loss ◽  
Propylene Oxide ◽  
Silica Aerogel ◽  
Sol Gel ◽  
Silica Aerogels ◽  
Silica Gels ◽  
High Porosity ◽  
Hydrophobic Silica ◽  
Sol Gel Process ◽  
Poly Propylene

Silica aerogel, the most common type of aerogels, comprised of 95% air in its structure which made the aerogel has a high surface area, high porosity, low density, and low thermal conductivity. Because of its structure and high porosity, one of its major weakness compared to other materials is being very brittle. This study aims at strengthening the connection points between silica nanoparticles using Pluronic10R5 (poly(propylene oxide)8–poly(ethylene oxide)22–poly(propylene oxide)8) where the Pluronic10R5 was used to reduce phase separation during the silica condensation reaction in the sol–gel process. Silica aerogel monoliths were prepared via a sol–gel process from hydrophobic silica gels and Pluronic10R5 with an ambient pressure drying (APD) process. Results from the compression test showed that the Pluronic10R5/silica aerogels have improved mechanical property by ten times that of unmodified silica aerogels. A thermogravimetric analysis (TGA) showed a mass loss at 300–400 °C that is attributed to the surface methyl group, while a mass loss at 200 °C refers to the loss of Pluronic10R5 which confirms the incorporation of Pluronic10R5 into the monolith. Moreover, infrared (IR) images revealed that the top surface temperature of Pluronic10R5/silica aerogels monolith is about 80 °C differs from the bottom heat source temperature of 160 °C.

Dual-porosity silica gels by polymer-incorporated sol-gel process

1992 ◽  
Vol 147-148 ◽  
pp. 291-295 ◽  
Author(s):  
Kazuki Nakanishi ◽  
Ryoji Takahashi ◽  
Naohiro Soga
Keyword(s):  
Sol Gel ◽  
Silica Gels ◽  
Dual Porosity ◽  
Sol Gel Process

Leaching Behavior of Edta In A Silica Sol-Gel Matrix

1994 ◽  
Vol 346 ◽  
Author(s):  
Kris S. Oka ◽  
J.D. Mackenzie
Keyword(s):  
Pore Volume ◽  
Sol Gel ◽  
Silica Matrix ◽  
Silica Gels ◽  
Volume Distribution ◽  
Leaching Behavior ◽  
Sol Gel Process ◽  
The Matrix ◽  
Physical Changes ◽  
Hydrolysis Of

ABSTRACTEthylene diamine tetra-acetic acid (EDTA) doped silica gels were made by the sol-gel process for the potential application as a filter for heavy metal ions in wastewater. The behavior of the organic molecule in the matrix was studied by investigating the percentage of EDTA leached out with a variation in the timing of addition of the EDTA molecule into the starting silica gel solution. Leach tests using water as the medium were performed for 2, 12 and 24 hours in order to determine the amount of EDTA trapped in the pores or in the matrix. A minimum amount of EDTA leached from the gels was detected in the samples to which EDTA was added 4 hours after initial hydrolysis of TEOS. This result was correlated to having a greater percentage of pore volume in the range of 15–20 Å, which was further substantiated with density measurements. The physical changes in the silica matrix altering the pore volume distribution were attributed to the addition of the water into which the EDTA molecule was initially dissolved.

scholarly journals Mesoporous silica matrices derived from sol-gel process assisted by low power ultrasonic activation

2009 ◽  
Vol 3 (1-2) ◽  
pp. 59-64 ◽  
Author(s):  
Cecilia Savii ◽  
László Almásy ◽  
Claudia Ionescu ◽  
Kinga Székely ◽  
Corina Enache ◽  
...  
Keyword(s):  
Low Power ◽  
Size Distribution ◽  
Rough Surface ◽  
Sol Gel ◽  
Silica Gels ◽  
Synthesis Process ◽  
Ultrasonic Activation ◽  
Sol Gel Process ◽  
Power Ultrasonic ◽  
Silica Matrices

The present work contributes to elucidating the differences between silica gels obtained by low doses ultrasonic activation, and those obtained by the conventional method, termed as classical sol gel. Silica matrices were produced by sol-gel synthesis process, assisted and non-assisted by an ultrasonic field, and subsequently characterized by various methods. Nitrogen adsorption and small-angle neutron scattering (SANS) measurements provided texture and microstructure of the dried gels. The adsorption results show that the sample sonicated for 2 hours presents the most ordered microstructure, characterized by pore shape close to spherical and the narrowest size distribution - about 90 % of the pores for this sample fall into the mesopore range (2-50 nm). SANS data reveal the formation of primary structural units of sizes around 1.5-2 nm which are small linear or branched polymeric species of roughly spherical shape and with rough surface. They are generated in the very early stage of sol gel process, as a result of hydrolysis and condensation reactions. The aggregated primary units form the secondary porous structure which can be described as a rough surface with fractal dimension above 2. The best porosity characteristics were obtained for the sample activated for 2 hours, indicating the optimal doses of sonication in the present conditions. Our results demonstrate the possibility of tailoring the pore size distribution using a low power ultrasonic bath. .

Synthesis of porphyrin-introduced silica gels by sol–gel process

2005 ◽  
Vol 286 (2) ◽  
pp. 812-815 ◽  
Author(s):  
Hidekazu Tanaka ◽  
Toshiyuki Yamada ◽  
Shinichiro Sugiyama ◽  
Hideo Shiratori ◽  
Ryozi Hino
Keyword(s):  
Sol Gel ◽  
Silica Gels ◽  
Sol Gel Process
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