Flexible and Transparent Silica Aerogels: An Overview

Parale, Vinayak G.; Lee, Kyu Yeon; Park, Hyung Ho

doi:10.4191/kcers.2017.54.3.12

Cited by 89 publications

(63 citation statements)

References 250 publications

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“…In contrast, the SP4 and SP4-3 samples exhibited superior thermal and mechanical properties to SP1, which suggests that PMMA blending and incorporation of silica aerogel powder effectively allows the acquisition of thermally and mechanically stable solid electrolytes [41]. In particular, the SP4-3 sample, containing 8 wt% silica aerogel and possessing the highest lithium-ion conductivity, showed no shrinkage or shape change after the application of thermal and mechanical stresses.…”

Section: Figurementioning

confidence: 95%

Fabrication of PEO-PMMA-LiClO4-Based Solid Polymer Electrolytes Containing Silica Aerogel Particles for All-Solid-State Lithium Batteries

2018

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To improve the ionic conductivity and thermal stability of a polyethylene oxide (PEO)-ethylene carbonate (EC)-LiClO4-based solid polymer electrolyte for lithium-ion batteries, polymethyl methacrylate (PMMA) and silica aerogel were incorporated into the PEO matrix. The effects of the PEO:PMMA molar ratio and the amount of silica aerogel on the structure of the PEO-PMMA-LiClO4 solid polymer electrolyte were studied by X-ray diffraction, Fourier-transform infrared spectroscopy and alternating current (AC) impedance measurements. The solid polymer electrolyte with PEO:PMMA = 8:1 and 8 wt% silica aerogel exhibited the highest lithium-ion conductivity (1.35 × 10−4 S∙cm−1 at 30 °C) and good mechanical stability. The enhanced amorphous character and high degree of dissociation of the LiClO4 salt were responsible for the high lithium-ion conductivity observed. Silica aerogels with a high specific surface area and mesoporosity could thus play an important role in the development of solid polymer electrolytes with improved structure and stability.

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Section: Figurementioning

confidence: 95%

Fabrication of PEO-PMMA-LiClO4-Based Solid Polymer Electrolytes Containing Silica Aerogel Particles for All-Solid-State Lithium Batteries

2018

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“…A silica (SiO 2 ) aerogel is an ultra‐porous (90–99% of theoretical density) material with a 3‐dimensional network structure of silica nanoparticles . Because of its interesting characteristics such as high specific surface area, low thermal conductivity, low dielectric constant, and low refractive index, it has received wide attention within various fields as a promising material for catalysis,, adsorption,, heat insulation, and drug delivery …”

Section: Figurementioning

confidence: 99%

Fast Synthesis of Spherical Silica Aerogel Powders by Emulsion Polymerization from Water Glass

Lee

Kim²,

Lee³

et al. 2018

ChemistrySelect

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In this study, a fast synthesis technique for silica aerogel powder was proposed that reduces the length of the tedious surface modification and solvent exchange processes. Spherical silica aerogel powder could be fabricated by an emulsion polymerization method from water glass and n-hexane. A stable water glass-in-hexane emulsion with a water glass to hexane ratio of 5:5 was fabricated using the surfactant, sorbitan monooleate (Span80). It was found that acetic acid and isopropanol catalysts for the hydrolysis and condensation of water glass droplets dispersed in the emulsion were crucial for the synthesis of the spherical silica aerogel powder with a narrow particle size distribution and for reducing production time. In addition, the particle size of the spherical silica aerogel could be controlled by changing the water glass droplet size.A silica (SiO 2 ) aerogel is an ultra-porous (90-99% of theoretical density) material with a 3-dimensional network structure of silica nanoparticles. [1] Because of its interesting characteristics such as high specific surface area, low thermal conductivity, low dielectric constant, and low refractive index, it has received wide attention within various fields as a promising material for catalysis, [2,3] adsorption, [4,5] heat insulation [6,7] and drug delivery. [8"9] Silica aerogels are normally synthesized via a sol-gel route from silicon alkoxides such as tetramethylorthosilicate (TMOS) or tetraethylorthosilicate (TEOS). A silica wet gel is formed as a result of a hydrolysis and condensation process of the silicon alkoxide molecules. The silica aerogel can then be obtained by a supercritical drying process with carbon dioxide (CO 2 ). [10,11] However, the alkoxide-derived silica aerogels use expensive precursors, and the supercritical drying process requires long processing times (low heating and depressurization rates) [12,13] which increases the overall cost of the aerogel.Ambient pressure drying (APD) is another option to produce silica aerogel, and water glass-based silica aerogels by APD has been extensively studied by many researchers. [14][15][16][17] The APD relies on surface modification and solvent exchange processes that are not only tedious but also economically unfavorable. Since surface modification agents (typically, trimethylchlorosilane (TMCS) or hexamethyldisilazane (HMDS)) can be transported within the silica hydrogel only by diffusion, APD requires processing times longer than a few or sometimes even tens of hours. [14][15][16] Recently, some groups have attempted to reduce the processing time of APD via a co-precursor method. [18][19][20] Huber et al. proposed a one-pot synthesis technique for a silica aerogel granulate, which could reduce solvent use and production time to within 4 h. However, they used an expensive precursor like polyethoxysiloxane (PEDS), and the morphology of the synthesized silica aerogel granulate was irregular. [21] Pan et al. prepared a silica aerogel powder via APD from water glass within 4 h. [22] Although the mechanical cru...

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“…The special class of materials having the air as main constituent (up to 98%) and solid material as a minimal constituent (up to 2%) are generally referred to as the 'Aerogels' [1]. The term aerogels became earmarked for the porous gels obtained by eliminating solvent from highly distended gels without or minimal collapsing of the gel network.…”

Section: Introductionmentioning

confidence: 99%

Physicochemical properties of ambient pressure dried surface modified silica aerogels: effect of pH variation

et al. 2020

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This work demonstrates the synthesis of hydrophobic silica aerogels from silicic acid with pH variations by using a costeffective and safe ambient pressure drying process. The work aims to evaluate the effect of pH variation on physicochemical properties of silica aerogels by standard techniques. In the present investigation, we have selected hexane as the solvent and trimethylchlorosilane/hexane was used to perform the surface modification of wet gel in order to elude the contraction and disintegration of gel association subsequent to a drying process. The effect pH on gelation in the form hydrolysis and condensation as well as on amorphous structure, physical properties such as density, thermal stability, surface area, pore-volume, pore radius, optical transmittance were investigated. FTIR spectroscopy was used to confirm the silylation (surface modification) of the prepared silica aerogel samples. Water contact angles were measured to verify the hydrphobic behaviour of all the samples. Among the prepared pH varied samples, the sample having pH ~ 5 shows better results such as high optical transmittance, thermal stability, hydrophobicity and high surface area.

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Flexible and Transparent Silica Aerogels: An Overview

Cited by 89 publications

References 250 publications

Fabrication of PEO-PMMA-LiClO4-Based Solid Polymer Electrolytes Containing Silica Aerogel Particles for All-Solid-State Lithium Batteries

Fabrication of PEO-PMMA-LiClO4-Based Solid Polymer Electrolytes Containing Silica Aerogel Particles for All-Solid-State Lithium Batteries

Fast Synthesis of Spherical Silica Aerogel Powders by Emulsion Polymerization from Water Glass

Physicochemical properties of ambient pressure dried surface modified silica aerogels: effect of pH variation

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