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

2006 ◽  
pp. 910-913
Author(s):  
Seung Hun Lee ◽  
Eun A Lee ◽  
Hae Jin Hwang ◽  
Ji Woong Moon ◽  
In Sub Han ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Ambient Pressure ◽  
Porous Silica ◽  
Silica Aerogels ◽  
Ambient Pressure Drying ◽  
Drying Method

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

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.

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.

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.

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 Properties of Hydrophobic Silica Aerogels by Ambient Pressure Drying Method

2011 ◽  
Vol 71-78 ◽  
pp. 1040-1043
Author(s):  
Hui Wang ◽  
Shi Ming Liu ◽  
Ling Ke Zeng
Keyword(s):  
Surface Area ◽  
Ambient Pressure ◽  
High Surface ◽  
High Surface Area ◽  
Volume Ratio ◽  
Silica Aerogels ◽  
Ambient Pressure Drying ◽  
Drying Method ◽  
Hydrophobic Properties ◽  
Large Pore Volume

Silica alcogels were prepared by hydrolysis with hydrochloric acid and condensation with NH4OH of ethanol diluted tetraethylorthosilicate (TEOS) precursor and trimethylchlorosilane and hexane as surface modifying agent. The physical properties such as density, appearance, hydrophobicity, surface area, pore size distribution and thermal stability were measured. It was found that the physical and hydrophobic properties of the silica aerogels depend on the TMCS/hexane (V) volume ratio. The density decreased with increase ofV, and the aerogels are more hydrophobic asV=3%. The aerogels were thermally stable up to a temperature of 350 °C, and the aerogel prepared has a high surface area and large pore volume.

scholarly journals Silica Aerogel Monoliths Derived from Silica Hydrosol with Various Surfactants

Molecules ◽  
2018 ◽  
Vol 23 (12) ◽  
pp. 3192 ◽  
Author(s):  
Dong Chen ◽  
Xiaodong Wang ◽  
Wenhui Ding ◽  
Wenbing Zou ◽  
Qiong Zhu ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Stability ◽  
Silica Aerogel ◽  
Low Cost ◽  
Ambient Pressure ◽  
Silica Aerogels ◽  
Ambient Pressure Drying ◽  
Low Thermal Conductivity ◽  
Silica Hydrosol ◽  
High Production Cost

Owing to their ultra-low thermal conductivity, silica aerogels are promising thermal insulators; however, their extensive application is limited by their high production cost. Thus, scientists have started to explore low-cost and easy preparation processes of silica aerogels. In this work, a low-cost method was proposed to prepare silica aerogels with industrial silica hydrosol and a subsequent ambient pressure drying (APD) process. Various surfactants (cationic, amphoteric, or anionic) were added to avoid solvent exchange and surface modification during the APD process. The effects of various surfactants on the microstructure, thermal conductivity, and thermal stability of the silica aerogels were studied. The results showed that the silica aerogels prepared with a cationic or anionic surfactant have better thermal stability than that prepared with an amphoteric surfactant. After being heated at 600 °C, the silica aerogel prepared with a cationic surfactant showed the highest specific surface area of 131 m2∙g−1 and the lowest thermal conductivity of 0.038 W∙m−1∙K−1. The obtained low-cost silica aerogel with low thermal conductivity could be widely applied as a thermal insulator for building and industrial energy-saving applications.

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