Synthesis of flexible silica aerogels using methyltrimethoxysilane (MTMS) precursor

Rao, A. Venkateswara; Bhagat, Sharad D.; Hirashima, Hiroshi; Pajonk, G.M.

doi:10.1016/j.jcis.2006.03.044

Cited by 357 publications

(86 citation statements)

References 18 publications

(14 reference statements)

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“…Lower MTES contents give bigger and non-spherical particles, while higher MTES contents produces smaller and more spherical particles with a more uniform size distribution [66]. Highly flexible and superhydrophobic silica aerogels can be synthesized from the silicon precursor methyltrimethoxysilane (MTMS) [67]. A study of tetramethoxysilane (TMOS) and methyltrimethoxysilane (MTMS) mixtures has proved that the increase of the MTMS/TMOS molar ratio is correlated with an increase in surface area and a decrease in average pore size [68].…”

Section: Influence Of Synthesis Conditions On Nanoporous Structurementioning

confidence: 99%

Influence of Chemical Conditions on the Nanoporous Structure of Silicate Aerogels

Sinkó

2010

Materials

137

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Silica or various silicate aerogels can be characterized by highly porous, open cell, low density structures. The synthesis parameters influence the three-dimensional porous structures by modifying the kinetics and mechanism of hydrolysis and condensation processes. Numerous investigations have shown that the structure of porous materials can be tailored by variations in synthesis conditions (e.g., the type of precursors, catalyst, and surfactants; the ratio of water/precursor; the concentrations; the medium pH; and the solvent). The objectives of this review are to summarize and elucidate the effects of chemical conditions on the nanoporous structure of sol-gel derived silicate aerogels.

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Section: Influence Of Synthesis Conditions On Nanoporous Structurementioning

confidence: 99%

Influence of Chemical Conditions on the Nanoporous Structure of Silicate Aerogels

Sinkó

2010

Materials

137

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“…However, the silica gel prepared with tetraethylsilicate had poor mechanical properties, and the shell of the microencapsulated PCM cracked easily. The mechanical properties of the silica gel prepared with methyl trimethoxysilane (MTES) can be improved [31,32].…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of Microencapsulated Paraffin Microcapsules as Shape-Stabilized Thermal Energy Storage Materials

Chen

Cao

Fang

et al. 2013

Nanoscale and Microscale Thermophysical Engineering

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This article presents the preparation and characterization of microencapsulated paraffin microcapsules with silicon dioxide (SiO 2 ) shells as thermal energy storage materials. The microcapsules were prepared using a sol-gel method. Paraffin was used as the core material, and SiO 2 prepared with methyl triethoxysilane (MTES) acted as the shell material. The morphology and particle size of the microcapsules were investigated using scanning electron microscopy (SEM). The chemical characterization of the microcapsules was measured using Fourier transform infrared spectroscope (FTIR). The crystalloid phase of the microcapsules was measured using X-ray diffraction (XRD). The thermal properties and thermal stability of the microcapsules were analyzed using differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The FTIR, XRD, and SEM results showed that the paraffin was encapsulated in the shell of the SiO 2 . The DSC results indicated that the typical microcapsules melted at 57.96 • C with a latent heat of 156.86 kJ/kg and solidified at 55.78 • C with a latent heat of 144.09 kJ/kg at microencapsulation ratio of 82.2%. The TGA and DTG results showed that the microcapsules had good thermal stability. The SiO 2 shells improved the thermal stability of the microcapsules.

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“…However, it appears that few attempts have been made to quantify the hydrophobicity of the materials in the context of their use for enzyme immobilization. There are some recent reports which describe the use of contact angle to quantify the hydrophobicity of films (Yoon and Kim, 2001) and aerogels (El Rassy et al, 2003;Venkateswara Rao et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

Use of water to evaluate hydrophobicity of organically-modified xerogel enzyme supports

Clifford

Legge

2005

Biotechnol. Bioeng.

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Silica xerogels are a new class of materials suitable for the immobilization of enzymes for various applications including biotransformations and biosensors. The physicochemical properties of xerogels, such as hydrophobicity, can be manipulated by the introduction of organically-modified silicates. This allows the immobilization matrix to be engineered to suit the enzyme and its application. Interfacial activation of lipase is a phenomenon in which the enzyme displays increased activity when it is bound to a hydrophobic interface. Lipase was entrapped in organically-modified xerogels in which the hydrophobicity of the enzyme support was modulated by the selection of different alkyltrimethoxysilane co-precursors and the ratio in which they were combined with tetramethyl orthosilicate. Interaction between the enzyme support and water was investigated with two methods to quantitatively assess the hydrophobicity of the entrapment matrix. The contact angle formed between the xerogel and water was used to determine hydrophobicity on a macroscopic level. Temperature-controlled water desorption was used to determine hydrophobicity on a microscopic level. Both methods were suitable for quantitatively discriminating between hydrophobic and hydrophilic materials. Further, the hydrophobicity of the enzyme support influenced the hydrolytic activity of the entrapped lipase under non-aqueous conditions. The specific activity of lipase increased only when entrapped in xerogels which could be classified as hydrophobic materials, that is with contact angles greater than 90 degrees or hydrophobicity values as determined by water desorption greater than 0.65.

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Synthesis of flexible silica aerogels using methyltrimethoxysilane (MTMS) precursor

Cited by 357 publications

References 18 publications

Influence of Chemical Conditions on the Nanoporous Structure of Silicate Aerogels

Influence of Chemical Conditions on the Nanoporous Structure of Silicate Aerogels

Synthesis and Characterization of Microencapsulated Paraffin Microcapsules as Shape-Stabilized Thermal Energy Storage Materials

Use of water to evaluate hydrophobicity of organically-modified xerogel enzyme supports

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