Effect of different types of surfactants on the microstructure of methyltrimethoxysilane-derived silica aerogels: A combined experimental and computational approach

Vareda, João P.; Maximiano, Pedro; Cunha, Luis Paulo Azevedo Henriques; Ferreira, André F.; Simões, Pedro; Durães, Luísa

doi:10.1016/j.jcis.2017.10.035

Cited by 45 publications

(18 citation statements)

References 47 publications

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“…The broad band at about 3500 cm −1 revealed O−H stretching bands originated from H−O‐H⋅⋅⋅H 2 O and SiO−H⋅⋅⋅H 2 O groups. The peak belonging to adsorbed water molecules was appeared at 1597 cm −1 . It is clearly seen that the intensity of broad band at 3500 cm −1 and peak at 1597 cm −1 decreased in the order of aging solvents: methanol < isopropanol < ethanol < n‐propanol that can be explained with molecular structure of solvents as shown in Scheme 1S.…”

Section: Resultsmentioning

confidence: 83%

“…So, vapor pressure and chemical structure of solvents become significant among other parameters . Before drying, silica gel washing treatment with water, solvent or mixture of water/solvent is important to remove impurities and unreacted materials . Entrapped solvent in silica gel is exchanged with air by different drying methods which include many variables such as temperature, pressure and time.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Aging Solvents on Physicochemical and Thermal Properties of Silica Xerogels Derived from Steel Slag

Kaya¹,

Deveci²

2020

ChemistrySelect

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Silica xerogels were synthesized from steel slag by sol-gel method with ambient pressure drying. Effect of aging solvents (methanol, ethanol, n-propanol and isopropanol) on properties of silica xerogels was investigated. Formation of amorphous structure and silica network of silica xerogels was confirmed by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy analysis, respectively. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) analyses revealed highly porous structure silica xerogel aged in isopropanol. Specific surface area and pore volume of silica xerogels increased in the order: n-propanol < ethanol < methanol < isopropanol. Specific surface area of silica xerogel aged in isopropanol was 481 m 2 g À 1 . Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) presented that highest thermal stability of silica xerogel was obtained in the presence of methanol. Lowest thermal conductivity and bulk density were specified with isopropanol as 0.046 g cm À 3 and 0.036 W m À 1 K À 1 .[a] G.

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Section: Resultsmentioning

confidence: 83%

Section: Introductionmentioning

confidence: 99%

Effect of Aging Solvents on Physicochemical and Thermal Properties of Silica Xerogels Derived from Steel Slag

Kaya¹,

Deveci²

2020

ChemistrySelect

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“…Here, organic surfactants and micelles act like a “pore-forming agent”. Moreover, some recent works [21,22,23,24] on the effect of surfactants in silica aerogels have also reported.…”

Section: Introductionmentioning

confidence: 99%

Silica Aerogel Monoliths Derived from Silica Hydrosol with Various Surfactants

et al. 2018

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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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“…The synthesis conditions also affect the aggregations influencing the particle size, pore formation, and chain branching. As a result, the macroscopic properties like pore size, porosity, bulk density, and surface area can be changed [16]. Very few research reports are available in the literature about the effect of pH on the physicochemical parameters of silica aerogel.…”

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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Effect of different types of surfactants on the microstructure of methyltrimethoxysilane-derived silica aerogels: A combined experimental and computational approach

Cited by 45 publications

References 47 publications

Effect of Aging Solvents on Physicochemical and Thermal Properties of Silica Xerogels Derived from Steel Slag

Effect of Aging Solvents on Physicochemical and Thermal Properties of Silica Xerogels Derived from Steel Slag

Silica Aerogel Monoliths Derived from Silica Hydrosol with Various Surfactants

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

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