Hydrophobic Silica Aerogels: Review of Synthesis, Properties and Applications

Anderson, Ann M.; Carroll, Mary K.

doi:10.1007/978-1-4419-7589-8_3

Cited by 36 publications

(35 citation statements)

References 93 publications

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“…In fact, they were already used as capture medium for hypervelocity cosmic particles (in Stardust) and as thermal insulators for Mars exploration (Mars Pathfinder, Mars Rovers, Mars Science Lander) [1]. However, whereas native silica aerogels are very brittle and deteriorate over time upon exposure to moisture, the MTMS-derived aerogels do not show these weaknesses due to their high flexibility and hydrophobicity [2][3][4][5]. The later exhibit very low bulk density (∼50 kg m −3 ) and thermal conductivity (achieving 0036 W m −1 K −1 ), high porosity (>95%) and surface area (∼500 m 2 g −1 ), good flexibility (order of kPa) and high hydrophobic character (∼140 • ) [5,6].…”

Section: Introductionmentioning

confidence: 99%

Effect of additives on the properties of silica based aerogels synthesized from methyltrimethoxysilane (MTMS)

Durães

Maia

Portugal

2015

The Journal of Supercritical Fluids

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Section: Introductionmentioning

confidence: 99%

Effect of additives on the properties of silica based aerogels synthesized from methyltrimethoxysilane (MTMS)

Durães

Maia

Portugal

2015

The Journal of Supercritical Fluids

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“…The degree of hydrophobicity of treated surfaces was assessed by measuring the contact angle (θ) between a drop of water and the surface. A goniometer device was used for this purpose; it involves a video recording system, which is attached to a digital image-processing programme (Anderson and Carroll 2011).…”

Section: Hydrophobicity Measurementmentioning

confidence: 99%

“…Increasing the contact angle results in increasing the hydrophobicity of the surface; surfaces with contact angles higher than 90°are considered hydrophobic. However, if the contact angle has reached or exceeded 150°, then the material is considered super-hydrophobic (Anderson and Carroll 2011).…”

Section: Hydrophobicity Measurementmentioning

confidence: 99%

Moisture evaluation of concrete pavement treated with hydrophobic surface impregnants

Al-Kheetan,

Rahman,

Chamberlain

2019

International Journal of Pavement Engineering

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Despite excellent service history, concrete pavement faces accelerated deterioration due to water and chemical ingress through micro cracks and surface voids. Surface protection could be an inexpensive way of enhancing the durability of concrete pavement. This research focuses on evaluating the performance of three surface applied hydrophobic materials with different chemistries; fluoropolymer, silicate resin and sodium acetate crystallising material. Tests consisted of a microscopic study to assess the mechanism of treatment, contact angle and pendulum tests to evaluate the hydrophobicity and frictional properties of treatment respectively. Also, surface absorption and water intake tests were conducted to appraise the resistance of treatment to absorb water. It was found that all three materials are capable of developing a hydrophobic effect in concrete, but with different efficacy in reducing water absorption. The rate of water absorption was minimum for sodium acetate compared to fluoropolymer and silicate resin treatments. Scanning Electron Microscope (SEM) analysis revealed different interaction approaches for the three materials with concrete.

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“…At present, aerogel-based insulation is under development for space TEG technology [5]. Aerogel was first produced in the 1930s [6], and is a unique class of materials exhibiting high specific surface area (200-1200 m 2 /g), high porosity (80-99%), low density (< 0.05 g/cm 3 ) and low thermal conductivity (< 0.02 W/(m.K)) [7][8][9][10][11]. When prepared using silica or carbon, aerogel can achieve the lowest thermal conductivity (< 0.01 W/(m.K) at 298 K) of any material, making it an appealing candidate for thermal insulation [7].…”

Section: Introductionmentioning

confidence: 99%

Cast-in-place, ambiently-dried, silica-based, high-temperature insulation

et al. 2017

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A novel sol-gel chemistry approach was developed to enable the simple integration of a cast-inplace, ambiently-dried insulation into high temperature applications. The insulation was silicabased and synthesized using methyltrimethoxysilane (MTMS) as the precursor. MTMS created a unique silica microstructure that was mechanically robust, macroporous, and superhydrophobic.To allow for casting into and around small, orthogonal features, zirconia fibers were added to increase stiffness and minimize contraction that could otherwise cause cracking during drying.Nano-sized titania powder was incorporated as an opacifier to reduce radiative heat transport. To assess relevance to high temperature thermoelectric generator technology, a comprehensive set of materials characterization experiments were conducted. The silica gel was thermally stable, retained superhydrophobicity with a water contact angle >150°, and showed a high electrical resistance >1 G ohm, regardless of heating temperature (up to 600 °C in Ar for 4 h). In addition,The silica-based thermal insulation exhibited a Young's modulus ~3.7 MPa and a low thermal conductivity < 0.08 W/(m.K) at room temperature before and after heat treatment (up to 600 °C in Ar for 4 h). Thus, based on the simplicity of the manufacturing process and the optimized material properties, we believe this technology can act as an effective cast-in-place thermal

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Hydrophobic Silica Aerogels: Review of Synthesis, Properties and Applications

Cited by 36 publications

References 93 publications

Effect of additives on the properties of silica based aerogels synthesized from methyltrimethoxysilane (MTMS)

Effect of additives on the properties of silica based aerogels synthesized from methyltrimethoxysilane (MTMS)

Moisture evaluation of concrete pavement treated with hydrophobic surface impregnants

Cast-in-place, ambiently-dried, silica-based, high-temperature insulation

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