Solvents Effects on Physicochemical Properties of Nano-Porous Silica Aerogels Prepared by Ambient Pressure Drying Method

2006 ◽  
Vol 510-511 ◽  
pp. 910-913 ◽  
Author(s):  
Seung Hun Lee ◽  
Eun A Lee ◽  
Hae Jin Hwang ◽  
Ji Woong Moon ◽  
In Sub Han ◽  
...  
Keyword(s):  
Ph Value ◽  
Ambient Pressure ◽  
Average Pore Size ◽  
Porous Silica ◽  
Sodium Silicate Solution ◽  
Silicate Solution ◽  
Silica Aerogels ◽  
Ambient Pressure Drying ◽  
Drying Method ◽  
Average Pore

Hydrophobic silica aerogels were synthesized by an ambient pressure drying method from silicic acid with a different pH value, which was prepared from sodium silicate solution (water glass). In this study we chose various hydrocarbon class solvents such as pentane, hexane, heptane, and toluene, and performed surface modification in TMCS (trimethylchlorosilane)/solvent solutions in order to improve reproducibility in aerogel production. Densities of the aerogels were about 0.1 ~ 0.3 g/cm3 , and apparent porosities were 88 ~ 96 %, depending on the processing conditions. Specific surface area was approximately 730 ~ 950 m2/g, and average pore size around 10 nm.

Synthesis of Silica Aerogel Thin Film from Waterglass

2007 ◽  
Vol 124-126 ◽  
pp. 671-674 ◽  
Author(s):  
Young Chul Cha ◽  
Chul Eui Kim ◽  
Seung Hun Lee ◽  
Hae Jin Hwang ◽  
Ji Woong Moon ◽  
...  
Keyword(s):  
Thin Film ◽  
Water Glass ◽  
Ph Value ◽  
Ambient Pressure ◽  
Silica Aerogels ◽  
Dip Coating ◽  
Ambient Pressure Drying ◽  
Drying Method ◽  
Silica Precursor ◽  
Dip Coating Technique

Hydrophobic thin film silica aerogels were synthesized by ambient pressure drying method from silicic acid which was prepared from sodium silicate (water glass) solution. The pH value of the silica precursor sol was adjusted to make a spinable sol, and gel films were coated on a glass substrate by dip coating technique. Aerogel-like thin films with the thickness of about 1 μm could be successfully fabricated by repeating the dip coating process three times.

scholarly journals Effect of sodium bicarbonate solution on methyltrimethoxysilane-derived silica aerogels dried at ambient pressure

2021 ◽  
Author(s):  
Yujing Liu ◽  
Xiao Han ◽  
Balati Kuerbanjiang ◽  
Vlado K. Lazarov ◽  
Lidija Šiller
Keyword(s):  
Contact Angle ◽  
Sodium Bicarbonate ◽  
Pore Diameter ◽  
Ambient Pressure ◽  
Sodium Bicarbonate Solution ◽  
Hydrophobic Surface ◽  
Silica Aerogels ◽  
Ambient Pressure Drying ◽  
Drying Method ◽  
Average Pore

AbstractHere we present an economical ambient pressure drying method of preparing monolithic silica aerogels from methyltrimethoxysilane precursor while using sodium bicarbonate solution as the exchanging solvent. We prepared silica aerogels with a density and a specific surface area of 0.053 g·cm−3 and 423 m2·g−1, respectively. The average pore diameter of silica aerogels is 23 nm as the pore specific volume is 1.11 cm3·g−1. Further, the contact angle between water droplet and the surface of silica aerogels in specific condition can be as high as 166°, which indicates a super-hydrophobic surface of aerogels.

Preparation and Characterization of Hydrophobic Silica Aerogel by Ambient Pressure Drying Method

2013 ◽  
Vol 544 ◽  
pp. 144-147 ◽  
Author(s):  
Hui Xu ◽  
Gui Ln Fu ◽  
Yu Qiang Guo ◽  
Jing Chun Tu ◽  
Yong Chen
Keyword(s):  
Silica Aerogel ◽  
Ambient Pressure ◽  
Average Pore Size ◽  
Ambient Pressure Drying ◽  
Solvent Exchange ◽  
Drying Method ◽  
Average Pore ◽  
Ft Ir ◽  
Hexane Solution

Silica aerogel has been prepared by ambient pressure drying technique using water glass as starting materials. Solvent exchange and surface modification were simultaneously conducted by immersing the wet hydrogel in EtOH/TMCS(Tri Methyl Chloro Silane)/hexane solution. The silica aerogel was obtained with the density of 0.110g•cm-3 and 95.2% porosity. The specific surface area of the silica aerogel was 472.5m2•g-1 with a average pore size distrubution of 27.5nm. FT-IR spectrum analysis showed that the surface of the silica aerogel was modified by Si-CH3 groups, which allowed the aerogel to be hydrophobic.

Preparation of Hydrophobic Silica Aerogels from Industrial Microsilica and its Oil Adsorption Properties

2012 ◽  
Vol 531-532 ◽  
pp. 103-107 ◽  
Author(s):  
Fei Shi ◽  
Jing Xiao Liu ◽  
Xiao Li Dong ◽  
Zhi Wei Zhang ◽  
Peng Cheng Du ◽  
...  
Keyword(s):  
Sodium Silicate ◽  
Hydrothermal Reaction ◽  
Ambient Pressure ◽  
Sodium Silicate Solution ◽  
Silicate Solution ◽  
Silica Aerogels ◽  
Ambient Pressure Drying ◽  
Mixed Solution ◽  
Hydrophobic Silica ◽  
Oil Adsorption

Hydrophobic silica aerogels were prepared from industrial microsilica via ambient pressure drying. The process consists of two stages, synthesis of sodium silicate solution from microsilica by hydrothermal reaction with sodium hydroxide, and preparation of silica aqueous gel and porous silica aerogels from the obtained sodium silicate solution. The mixed solution of hexane/ethanol/trimethylchlorosilane was used to modify the sol-gel derived silica aqueous gel so as to obtain porous structure by ambient pressure drying. The microstructure, pore properties of the silica aerogels were analyzed by FTIR and N2 adsorption-desorption methods, and the oil adsorption of the synthesized silica aerogels was investigated. The results indicate that the obtained silica aerogels are light-weight and hydrophobic porous materials, with the specific surface area of 767~828 m2•g-1, porosity of 91.5~95.1% and the average pore diameter of 5.22~8.02 nm. The synthesized silica aerogels have good oil adsorption capacity and the highest saturated oil adsorption rate can achieve 1105%.

Cellulose nanofibril reinforced silica aerogels: optimization of the preparation process evaluated by a response surface methodology

RSC Advances ◽  
2016 ◽  
Vol 6 (102) ◽  
pp. 100326-100333 ◽  
Author(s):  
Jingjing Fu ◽  
Chunxia He ◽  
Jingda Huang ◽  
Zhilin Chen ◽  
Siqun Wang
Keyword(s):  
Mechanical Properties ◽  
Response Surface Methodology ◽  
Response Surface ◽  
Ambient Pressure ◽  
Silica Aerogels ◽  
Ambient Pressure Drying ◽  
Preparation Process ◽  
Cellulose Nanofibril ◽  
Drying Method ◽  
Composite Aerogels

CNF–silica composite aerogels with reinforced mechanical properties were prepared under an ambient pressure drying method and optimized by a response surface methodology.

The effect of pH on the physicochemical properties of silica aerogels prepared by an ambient pressure drying method

2007 ◽  
Vol 61 (14-15) ◽  
pp. 3130-3133 ◽  
Author(s):  
Seunghun Lee ◽  
Young Chul Cha ◽  
Hae Jin Hwang ◽  
Ji-Woong Moon ◽  
In Sub Han
Keyword(s):  
Physicochemical Properties ◽  
Ambient Pressure ◽  
Silica Aerogels ◽  
Ambient Pressure Drying ◽  
Drying Method ◽  
Effect Of Ph

scholarly journals Eco-Friendly Synthesis of Water-Glass-Based Silica Aerogels via Catechol-Based Modifier

Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2406
Author(s):  
Hyeonjung Kim ◽  
Kangyong Kim ◽  
Hyunhong Kim ◽  
Doo Jin Lee ◽  
Jongnam Park
Keyword(s):  
Water Glass ◽  
Ambient Pressure ◽  
Cost Effective ◽  
Silica Aerogels ◽  
Ambient Pressure Drying ◽  
Drying Process ◽  
Average Pore ◽  
Glass Silica ◽  
Effective Water ◽  
Alkoxide Precursors

Silica aerogels have attracted much attention owing to their excellent thermal insulation properties. However, the conventional synthesis of silica aerogels involves the use of expensive and toxic alkoxide precursors and surface modifiers such as trimethylchlorosilane. In this study, cost-effective water-glass silica aerogels were synthesized using an eco-friendly catechol derivative surface modifier instead of trimethylchlorosilane. Polydopamine was introduced to increase adhesion to the SiO2 surface. The addition of 4-tert-butyl catechol and hexylamine imparted hydrophobicity to the surface and suppressed the polymerization of the polydopamine. After an ambient pressure drying process, catechol-modified aerogel exhibited a specific surface area of 377 m2/g and an average pore diameter of approximately 21 nm. To investigate their thermal conductivities, glass wool sheets were impregnated with catechol-modified aerogel. The thermal conductivity was 40.4 mWm−1K−1, which is lower than that of xerogel at 48.7 mWm−1K−1. Thus, by precisely controlling the catechol coating in the mesoporous framework, an eco-friendly synthetic method for aerogel preparation is proposed.

Permittivities of Ultra-Low Dielectric Silica Beads and Aerogels

2015 ◽  
Vol 830-831 ◽  
pp. 444-447
Author(s):  
S. Nagapriya ◽  
B. Masin ◽  
H. Sreemoolanadhan ◽  
M.R. Ajith ◽  
Mariamma Mathew ◽  
...  
Keyword(s):  
High Speed ◽  
Ambient Pressure ◽  
Porous Silica ◽  
Silica Aerogels ◽  
Ambient Pressure Drying ◽  
Inorganic Materials ◽  
Silica Gels ◽  
Low Dielectric ◽  
Silica Beads ◽  
Lcr Meter

Materials with relative permittivity or dielectric constant near to that of air (εr~1) are known as ‘ultra-low k’ materials. They find a number of applications in inter-connects of micro-electronic circuits, antennae, high-speed communication substrates etc. Among the inorganic materials, porous silica is the widely studied candidate. Porous silica can be of many types depending upon the extent of porosity and size and connectivity of pores. This paper presents the details of measurement of permittivities and the results of silica beads and silica aerogels. Silica beads, prepared by microwave heating of silica gels, are spherical beads of average 1mm size. Hydrophobic silica aerogels, prepared by ambient pressure drying of silica gels, are irregular chunks of 5-10 mm size. Both are potential bulk fill insulation materials and hence the permittivity can be measured as an aggregate filling a definite volume. The permittivities of these have been measured upto 1 MHz by 3-terminal method using a precision LCR meter and a powder-paste cell as per ASTM-D150-11. The εr values of silica aerogels and silica beads in 20 Hz-1 MHz range could be measured and are less than 1.6 at 1 MHz.

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