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(a) Condensation reaction between hydrolyzed MTMS monomers, (b) schematic representation of hard and flexible silica aerogels and (c) photographs of silica aerogel (M=35): The measured length of before/during/after 60% strain-induced loading were 45/ 18/44 mm, respectively.
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The flexible and superhydrophobic properties of silica aerogels are extremely important material for thermal insulation and oil spill cleanup applications for their long-term use. Flexible silica aerogels were synthesized by using a two-step sol-gel process with precursors, methyltrimethoxysilane (MTMS) followed by supercritical drying. Silica aero...
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... of aerogels In the present paper, MTMS (H 3 C-Si-(OCH 3 ) 3 ) precursor used as a trifunctional organosilane compound to synthe- size superhydrophobic and flexible aerogels. Figure 1(a) corresponds to the condensation reaction between hydro- lyzed MTMS monomers. Figure 1(b) showed schematic representation of the hard and flexible structured silica aerogels prepared with M=28 and M=35, respectively. ...
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... 1(a) corresponds to the condensation reaction between hydro- lyzed MTMS monomers. Figure 1(b) showed schematic representation of the hard and flexible structured silica aerogels prepared with M=28 and M=35, respectively. Figure 1(c) demonstrates the elastic nature of silica aero- gels (M=35) by measuring the length of the cylindrical shaped silica aerogel with 60% strain-induced loading. ...
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... 1(b) showed schematic representation of the hard and flexible structured silica aerogels prepared with M=28 and M=35, respectively. Figure 1(c) demonstrates the elastic nature of silica aero- gels (M=35) by measuring the length of the cylindrical shaped silica aerogel with 60% strain-induced loading. The measured length of before/during/after loading were 45/18/ 44 mm, respectively and it could be confirmed that an excellent flexibility can be obtained for a silica aerogel by increasing solvent quantity in the sol using MTMS precursor. ...
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... flexibility can be obtained for a silica aerogel by increasing solvent quantity in the sol using MTMS precursor. The flexibility was observed for higher molar ratio of MeOH:MTMS i.e. by increasing solvent quantity, linear polymerization and distance between silica clusters can be increased to get flexible properties as schematic shown in Fig. 1(b). In the case of MTMS precursor, each monomer of the MTMS has one non-hydrolysable methyl group (CH 3 ) and three hydrolysable methoxy groups (OCH 3 ). Therefore, only hydrolysable methoxy groups are responsible for the matrix formation by undergoing the fol- lowing hydrolysis and condensation sol-gel reactions. 2) 3.2. FT-IR studies of ...
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Silica aerogel was often reinforced with glass fiber and changed to hydrophobicity via a surface modification to overcome its fragile and hygroscopic nature for practical application. However, though the mechanical and hydrophobic performances of the silica aerogel were improved, its unique ultra-low thermal conductivity was compromised. In order t...
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... A broad-band peak of Si-OH was observed from 3000 to 3700 cm −1 . The characteristic peak that appeared at the position of 1638 cm −1 was assigned to be the bending of a hydrophilic primary amine -NH 2 [33], which confirmed the participation of APTES in the sol-gel reactions for the A1, A2, and A3 MSPs. On the other hand, for the characterization of the M1 and M2 hydrophobic MSPs, the characteristic peak for the asymmetric absorption of Si-CH 3 and hydrophobic -CH 3 was observed at the positions of 1279 and 2968 cm −1 [34], respectively, which confirmed the participation of MTMS in the sol-gel reactions of M1 and M2. ...
In this paper, comparative studies of hydrophilic and hydrophobic mesoporous silica particles (MSPs) on the dielectric properties of their derivative polyester imide (PEI) composite membranes were investigated. A series of hydrophilic and hydrophobic MSPs were synthesized with the base-catalyzed sol-gel process of TEOS, MTMS, and APTES at a distinctive feeding ratio with a non-surfactant template of D-(-)-Fructose as the pore-forming agent. Subsequently, the MSPs were blended with the diamine of APAB, followed by introducing the dianhydride of TAHQ with mechanical stirring for 24 h. The obtained viscous solution was subsequently coated onto a copper foil, 36 μm in thickness, followed by performing thermal imidization at specifically programmed heating. The dielectric constant of the prepared membranes was found to show an obvious trend: PEI containing hydrophilic MSPs > PEI > PEI containing hydrophobic MSPs. Moreover, the higher the loading of hydrophilic MSPs, the higher the value of the dielectric constant and loss tangent. On the contrary, the higher the loading of hydrophobic MSPs, the lower the value of the dielectric constant with an almost unchanged loss tangent.
... A highly concentrated energy retention peak may be identified at 1098 cm −1 due to imbalanced of Si-O-Si. 20,21 Result clearly shows PDMS/MTMS nanocomposite outperforms PDMS composite. 22,23 The C=O group is represented by the incredibly sharp peak at 1742 cm −1 . ...
Among all the astonishing equipment found in power transmission and distribution networks, the insulator plays a vital role by providing mechanical support and electrical protection to power system. Despite of all these noteworthy facts, the breakdown of insulators owing to surface contaminants appears to be particularly fascinating in today's scientific world. Researchers provide a plethora of methods to eradicate this problem. From all method, superhydrophobic coating provide better solution for its resistance to moisture, wetness, dust and ice. This unique property of superhydrophobic coatings requires further investigation. Hence, the suggested technique achieves this purpose by preparing the eco-friendly superhydrophobic solution of PDMS (Polydimethylsiloxane) with MTMS (Methyl tri methoxy silane) composites. In this study superhydrophobic coating were prepared by using sol-gel method and spray coating technique Analysis like FTIR, surface morphology and coating thermal study were included. self-cleaning ability of superhydrophobic coating on insulator surface with contact angle (CA) was measured from 165° to 170° and sliding angle 5° to 10° confirming superhydrophobic property. Finally, in an intentionally contaminated conditions based on solid layer method of IEC60507 standards and IEC 60587 standards insulation resistance are tested using a megger instrument.
... Moreover, the two alkoxysilanes differ in the length and the chemical composition of the alkyl chain. MTMS contains a short hydrophobic non-polar methyl group, which minimizes inter-chain cohesion during polymerization and allow forming an almost linear and very flexible polymer (Mahadik et al., 2016) able to penetrate the cell wall. The presence of a longer propyl chain terminated with a thiol group makes the MPTES molecule more hydrophobic, which limits its penetrability into wood decreasing uptake (Donath et al., 2004). ...
... It leads to rearrangements within the previously formed silane network making it more unstable (Donath et al., 2004). Additionally, due to the non-polar nature of the methyl chain the resulting three-dimensional polymer network is very elastic and flexible (Mahadik et al., 2016). This two features (i.e. ...
Archaeological waterlogged elm wood was treated with methyltrimethoxysilane (MTMS) and (3-mercaptopropyl)trimethoxysilane (MPTES), respectively, and anti-shrink efficiency and sorption properties of the impregnated wood samples were determined. The applied impregnants stabilized wood dimensions efficiently enough, i.e. the obtained anti-shrink efficiency was 81% and 98% for MTMS- and MPTES-treated wood, respectively. Both alkoxysilanes can be considered as potential new consolidants. Hygroscopic properties of untreated and impregnated wood were investigated with the DVS experiments. The application of MTMS and MPTES reduced wood equilibrium moisture content (EMC) and sorption hysteresis e.g. hysteresis relative change was -83.7 and -73.7% for MTMS- and MPTES-treated wood, respectively. The EMC reduction was observed in the whole hygroscopic range and it was primary due to the monolayer capacity decrease to 50 and 30% of the value for untreated wood and observed for adsorption and desorption modes, respectively. The DVS experiments revealed chemical instability of the MTMS-wood system which was neutralized after the cyclic sorption. The possible scenarios of the interaction of both alkoxysilanes with wood structure were discussed.
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... A methyltrimethoxysilane (MTMS) silica precursor was used to incorporate hydrophobicity. Rao et al. [17] first reported the synthesis of a flexible aerogel using an MTMS silica precursor by a supercritical drying method. However, it was fragile and brittle like a conventional aerogel, so a reinforcement process was required. ...
... Three types of silicon bonding were observed from 1500 cm -1 to 500 cm -1 . Si-C bonding at 1250 cm -1 comes from the methyl group and silicon atom of the MTMS precursor [17]. At 1000 cm -1 and 750 cm -1 , Si-O-Si and Si-O absorption peaks were observed from the MTMS silica aerogel. ...
To complement the low mechanical strength of pristine methyltrimethoxysilane (MTMS) silica aerogels, a composite silica aerogel with structurally strong multi-wall carbon nanotubes (MWCNTs) was synthesised by supercritical drying. The surface structure of stable MWCNTs was oxidised and defected by acid treatment to attach carboxyl groups, which result in good dispersibility of the MWCNTs. By a sol–gel process, functionalised MWCNTs formed a network structure with the MTMS silica sol. Through the compositisation of the MTMS silica aerogel with functionalised MWCNTs, the mechanical strength of the composite aerogel became higher than that of the pristine MTMS silica aerogel; changes in the surface characteristics, chemical bonding state, and microstructure were also observed. The aerogels exhibit hydrophobicity except at the functionalised MWCNTs, which impart hydrophilicity due to polar functional groups. Chemical bonding, including carbonyl and carboxyl bonds, was also observed following functionalisation. Some fibre structures of MWCNTs and pore characteristics in composites were observed.
... The several absorption peaks, observed at 1400 cm −1 and from 3000 to 2500 cm −1 , were due to bending and stretching modes of C-H bonds of monomers. 26) The strong peaks observed at 1700 cm −1 proved the presence of C=O bonds, and C-O-C peaks are also seen at from 1300 to 1000 cm −1 . 11) These peaks came from carbonyl group and ether group of 2-EHA monomers and 2-EHMA monomers. ...
In an effort to overcome the weakness of aerogel, polymer aerogels have been prepared by copolymerizing the different types of monomers through sol-gel process. Polymerizing the successive phase of a high internal phase emulsion, which has interconnected porous structure, porous polymer aerogel can be manufactured. In this paper, we use the styrene/divinylbenzene chain as a basic monomer structure, and additionally use 2-ethylhexyl methacrylate (2-EHMA) or 2-ethylhexyl acrylate (2-EHA) as monomers for distinguishing the visible mechanical properties of synthesized polymer aerogel. We can observe the different tendency of polymer aerogels by kinds of monomer or ratio. Flexibility and microstructure can be changed by the types of monomer. EHA polymer aerogel shows high flexibility and thin microstructure, and EHMA polymer aerogel shows high hardness and thick microstructure. EHA/EHMA polymer aerogel shows the intermediate nature between them. By utilizing the mechanical properties of three types of polymer aerogels to adequate situation or environment, polymer aerogels could be used as drug agent, ion exchange resin, oil filter and insulator, and so on.
The fragility of silica-based aerogels limits their potential use in various applications. These exceptional materials can be immobilized on more flexible insulation materials to form materials called ‘aerogel blankets’. In situ, sol-gel deposition is one way to synthesize aerogel material directly on the fibrous matrix. This study presents aerogel blankets’ formation and thermophysical performance obtained by in situ deposition of a methyltrimethoxysilane (MTMS) precursor prepared with sodium dodecyl sulphate surfactants. X-ray diffraction analysis indicates increased peak intensities, suggesting a more organized crystalline-like structure. Corresponding Raman spectroscopy and transmission electron microscopy (TEM) observations corroborate the results, highlighting the surfactant’s role in promoting structural order within the aerogel. A distinct silica spherical structure was also observed in the TEM analysis. The process was carried out at ambient pressure conditions; thus, the process is scalable for large-volume production. The MTMS concentration of the sol varied in the range of 5 to 30 wt.%, resulting in different aerogel characteristics deposited onto the ceramic fiber matrix. Samples were characterized mainly for their thermal, mechanical, and morphological properties. Remarkably, the thermal conductivity performance of the obtained composite blanket showed 30% lower heat conductivity than the pristine ceramic blanket.
A silver doped superhydrophobic silica coatings shows strong antibacterial activity against both gram positive and gram negative bacteria.
Water glass is much cheaper than silicon alkoxide, so it has advantage for commercialization. A condensation by acid catalyst makes considerable effect about the properties of water glass based silica aerogel among many factors in silica aerogel process. The pore structural properties of water glass based silica aerogel such as specific surface area and pore size distribution have been investigated through the changes in the amount and the kinds of acid catalyst. It has been confirmed that water glass based silica aerogel is affected by various conditions of catalyst in the condensation reaction such as the kind, concentration, and the amount of mole of acid catalyst on the properties of final products. Especially, it is checked that the effect of mole of acid is more prominent than that of concentration. In the case for conventional method with introducing 4M HCl in condensation step, the silica aerogel could be synthesized which has 394m^2/g of specific surface area, 2.20 cc/g of pore volume, 22.3 nm of average pore size, and 92.53% of porosity. On the other hand, when 4M sulfuric acid was used with 73 mmol at the condensation step of water glass based silica aerogel, the pore structural characteristics of water based silica aerogel showed better properties than the case of using HCl, for example, specific surface area was measured as 516m^2/g, and pore volume, average pore diameter, and porosity were obtained as 3.10 cc/g, 24.1 nm, and 96.1%, respectively.
Hydrophobic surfaces can be developed with low surface energy materials as per the Wenzel state. To intensify the adherence of the coating on the substrates, polymer has been employed in the coating. The Polymer-silica coating has been prepared with the help of PMMA (Poly methyl methacrylate), PS (Polystyrene) and MTMS (Methyltrimethoxy silane) in the study. Composite of PMMA/MTMS and PS/MTMS were coated uniformly on the substrates by spin-coating technique at a speed of 1500 and 1300 rpm. The functional groups have been identified with Fourier Transform Infrared Ray Spectroscopy. Property of low surface energy (ϒ), for hydrophobic surface can be evolved, with Hamaker's constant (A H ), Vander Waals interaction between the particles of opposite surface charge which form permanent dipoles. The contact angle for PMMA/MTMS is 112° and PS/MTMS is 119° is measured. Further, the optical and structural properties were designated by UV-Visible spectroscopy and FESEM. The particles of dust on the coated surface rolls off smoothly upon contact with the water droplet ensuring the self-cleaning nature.
Silica aerogels are attracting attention due to certain outstanding properties such as low bulk density, low thermal conductivity, high surface area, high porosity, high transparency and flexibility. Due to these extraordinary properties of aerogels, they have become a promising candidate in thermal superinsulation. The silica-based aerogels are brittle in nature, which constrains their large scale-application. It is necessary to achieve transparency and flexibility of silica-based aerogels at the same time and
with the same porous structure for optical field applications. Therefore, the present review focuses on the different sol-gel synthesis parameters and precursors in the synthesis of flexible as well as transparent silica aerogels. Also, a brief overview of reported flexible and transparent aerogels with some important properties and applications is provided
