A new trend for development of mechanically robust hybrid silica aerogels

Maleki, Hajar; Durães, Luísa; Portugal, António

doi:10.1016/j.matlet.2016.05.085

Cited by 20 publications

(6 citation statements)

References 9 publications

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“…Commercially available silica aerogels are being developed in different forms of blankets and granules and commercialized with a global market of ∼250 million €/ a . However, research on silica aerogels continues, as the mechanical strength of native silica aerogels is still suboptimal, and a further improvement of the mechanical stability with low or no sacrifice to the other physical properties is necessary. ,− The extension of network connectivity in the silica skeleton through cross-linking with various polymeric networks, such as polyurethane, epoxide, and polystyrene, to name only a few, results in mechanically more robust materials that are suitable for most load-bearing applications. − However, the bottlenecks with regard to compromises in the set of the physical properties as well as the multistep, non-green tedious processing approaches are still problematic.…”

Section: Introductionmentioning

confidence: 99%

Compressible, Thermally Insulating, and Fire Retardant Aerogels through Self-Assembling Silk Fibroin Biopolymers Inside a Silica Structure—An Approach towards 3D Printing of Aerogels

Maleki

Montes

Hayati-Roodbari

et al. 2018

ACS Appl. Mater. Interfaces

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135

110

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Thanks to the exceptional materials properties of silica aerogels, this fascinating highly porous material has found high-performance and real-life applications in various modern industries. However, a requirement for a broadening of these applications is based on the further improvement of the aerogel properties, especially with regard to mechanical strength and postsynthesis processability with minimum compromise to the other physical properties. Here, we report an entirely novel, simple, and aqueous-based synthesis approach to prepare mechanically robust aerogel hybrids by cogelation of silk fibroin (SF) biopolymer extracted from silkworm cocoons. The synthesis is based on sequential processes of acid catalyzed (physical) cross-linking of the SF biopolymer and simultaneous polycondensation of tetramethylorthosilicate (TMOS) in the presence of 5-(trimethoxysilyl)pentanoic acid (TMSPA) as a coupling agent and subsequent solvent exchange and supercritical drying. Extensive characterization by solid-state H NMR,Si NMR, and 2D H-Si heteronuclear correlation (HETCOR) MAS NMR spectroscopy as well as various microscopic techniques (SEM, TEM) and mechanical assessment confirmed the molecular-level homogeneity of the hybrid nanostructure. The developed silica-SF aerogel hybrids contained an improved set of material properties, such as low density (ρ = 0.11-0.2 g cm), high porosity (∼90%), high specific surface area (∼400-800 m g), and excellent flexibility in compression (up to 80% of strain) with three orders of magnitude improvement in the Young's modulus over that of pristine silica aerogels. In addition, the silica-SF hybrid aerogels are fire retardant and demonstrated excellent thermal insulation performance with thermal conductivities (λ) of 0.033-0.039 W m K. As a further advantage, the formulated hybrid silica-SF aerogel showed an excellent printability in the wet state using a microextrusion-based 3D printing approach. The printed structures had comparable properties to their monolith counterparts, improving postsynthesis processing or shaping of the silica aerogels significantly. Finally, the hybrid silica-SF aerogels reported here represent significant progress for a mechanically customized and robust aerogel for multipurpose applications, namely, as a customized thermal insulation material or as a dual porous open-cell biomaterial used in regenerative medicine.

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Section: Introductionmentioning

confidence: 99%

Compressible, Thermally Insulating, and Fire Retardant Aerogels through Self-Assembling Silk Fibroin Biopolymers Inside a Silica Structure—An Approach towards 3D Printing of Aerogels

Maleki

Montes

Hayati-Roodbari

et al. 2018

ACS Appl. Mater. Interfaces

Self Cite

135

110

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“…While the special skeleton of aerogel may be destroyed and nanoparticles may grow up at higher temperatures, both can acutely reduce the density and thermal properties of SiO 2 aerogel [6]. Many researches concentrated on strengthening the thermal stability and strength of the aerogel via the preparation of hybrid aerogels [7][8][9][10][11]. Kim et al [9] synthesized a glass fiber/silica aerogel, which possessed bigger pore size and specific surface area than aerogel composites made of only colloidal silica.…”

Section: Introduction mentioning

confidence: 99%

A study of morphological properties of SiO2 aerogels obtained at different temperatures

Liao

Gao

et al. 2018

J Adv Ceram

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In this paper, temperature dependence of nanoporous framework evolution process and variety of pore properties (pore volume, specific surface area (BET), and pore size) of SiO 2 aerogels were characterized by FTIR, XPS, XRD, SEM, TEM, BET, BJH, etc. Results show that SiO 2 aerogels treated at different temperatures all possess amorphous structure. With the increase of treated temperatures, BET values of SiO 2 aerogels increase initially and then decrease, and it reaches the maximum value of 882.81 m 2 /g when treated at 600 ℃ for 2 h due to the addition of the nanopores and shrinkage skeleton of SiO 2 aerogels. Higher temperatures may result in a framework transformation and particle growth; both factors could reduce the BET values of the aerogels. Nanoporous skeleton of SiO 2 aerogels at room temperatures is composed of tetrahedron with a pore size of about 22.28 nm. Higher treated temperatures result in an increase of octahedron amount in nanoporous framework and a decrease of pore size. When treated at 1000 ℃, an approximate dense SiO 2 bulk via the framework collapse and particle growth is obtained. These varieties are derived from the formed extra bonds of Si-O-Si, higher local stress, and liquid phase between particles during heat treatment process.

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“…In the past two decades, researchers believed that combining polymer and silica is an effective way to enhance the mechanical properties of aerogels [ 115 , 116 , 117 , 118 ]. Meanwhile, the results indicate that the interfaces between silica gel particles and polymers also have a great influence on aerogel properties [ 119 ].…”

Section: Polymer-modified Silica Aerogel Compositesmentioning

confidence: 99%

The Synthesis and Polymer-Reinforced Mechanical Properties of SiO2 Aerogels: A Review

et al. 2023

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Silica aerogels are considered as the distinguished materials of the future due to their extremely low thermal conductivity, low density, and high surface area. They are widely used in construction engineering, aeronautical domains, environmental protection, heat storage, etc. However, their fragile mechanical properties are the bottleneck restricting the engineering application of silica aerogels. This review briefly introduces the synthesis of silica aerogels, including the processes of sol–gel chemistry, aging, and drying. The effects of different silicon sources on the mechanical properties of silica aerogels are summarized. Moreover, the reaction mechanism of the three stages is also described. Then, five types of polymers that are commonly used to enhance the mechanical properties of silica aerogels are listed, and the current research progress is introduced. Finally, the outlook and prospects of the silica aerogels are proposed, and this paper further summarizes the methods of different polymers to enhance silica aerogels.

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A new trend for development of mechanically robust hybrid silica aerogels

Cited by 20 publications

References 9 publications

Compressible, Thermally Insulating, and Fire Retardant Aerogels through Self-Assembling Silk Fibroin Biopolymers Inside a Silica Structure—An Approach towards 3D Printing of Aerogels

Compressible, Thermally Insulating, and Fire Retardant Aerogels through Self-Assembling Silk Fibroin Biopolymers Inside a Silica Structure—An Approach towards 3D Printing of Aerogels

A study of morphological properties of SiO2 aerogels obtained at different temperatures

The Synthesis and Polymer-Reinforced Mechanical Properties of SiO2 Aerogels: A Review

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