Silica aerogel films prepared at ambient pressure by using surface derivatization to induce reversible drying shrinkage

Prakash, Sai S.; Brinker, C. Jeffrey; Hurd, Alan J.; Rao, Sudeep M.

doi:10.1038/374439a0

Cited by 438 publications

(269 citation statements)

References 11 publications

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“…During evaporation of solvent, the porous structure of the ormosil colloids first shrunk and then recoiled to its initial porous state due to the hydrophobic surface methyl groups. 41 Such ormosil coatings are deformable and mechanically and thermally stable and they adhere strongly to plastic (such as polyethersulfone, polyetherimide, and cellulose acetate) and glass substrates thanks to their hybrid nature. 26,50 To further improve integrity of coatings and their adhesion to glass surfaces, coatings were cured at 450°C for 1 h.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…After aging, 12 mL of methanol was added to the gels, and the resulting mixture was sonicated for 45 s at 20 W using an ultrasonic liquid homogenizer in order to obtain ormosil colloids. 26,41 The colloids were spin coated on clean glass surfaces at 2000 rpm and dried at room temperature overnight. To increase the hydrophobicity and integrity of the coatings, they were heated to 450°C for 1 h. The colloids and corresponding coatings were named with the number in the abbreviation indicating the TMOS volume fraction in the corresponding colloid, such that TM 7.5 indicates the coating produced using the colloid containing 7.5% TMOS and 92.5% MTMS.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

See 1 more Smart Citation

Superhydrophobic and Omnidirectional Antireflective Surfaces from Nanostructured Ormosil Colloids

Yıldırım

Khudiyev

Daglar

et al. 2013

ACS Appl. Mater. Interfaces

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A large-area superhydrophobic and omnidirectional antireflective nanostructured organically modified silica coating has been designed and prepared. The coating mimics the self-cleaning property of superhydrophobic lotus leaves and omnidirectional broad band antireflectivity of moth compound eyes, simultaneously. Water contact and sliding angles of the coating are around 160°and 10°, respectively. Coating improves the transmittance of the glass substrate around 4%, when coated on a single side of a glass, in visible and near-infrared region at normal incidence angles. At oblique incidence angles (up to 60°) improvement in transmission reaches to around 8%. In addition, coatings are mechanically stable against impact of water droplets from considerable heights. We believe that our inexpensive and durable multifunctional coatings are suitable for stepping out of the laboratory to practical outdoor applications.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

Superhydrophobic and Omnidirectional Antireflective Surfaces from Nanostructured Ormosil Colloids

Yıldırım

Khudiyev

Daglar

et al. 2013

ACS Appl. Mater. Interfaces

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“…In this context, the promise of template free methods is the production, by eliminating the harsh template removal steps, of nanoporous ormosil thin films at room temperature and neutral pH conditions. Although, Prakash et al 22 were able to prepare porous silica thin films under mild conditions from colloidal suspensions of surface modified silica gels, these films prove to be inflexible because of the rigid silica network. Also, our previous work 23 reports porous thin films from phase separated methyl silsesquioxane (MSQ) gels.…”

Section: Introductionmentioning

confidence: 99%

Template free preparation of nanoporous organically modified silica thin films on flexible substrates

et al. 2011

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We report the preparation and characterization of nanoporous organically modified silica (ormosil) thin films at room temperature and neutral pH conditions from homogeneous methyl silsesquioxane (MSQ) gels. Universally applicable and stable colloidal ormosil suspensions are prepared from the gels by sonication and coated to the substrates including glass, paper and plastics. The nanoporosity and thickness of the films can be tuned, which makes them suitable for certain applications including sensing, functional coatings, and low-dielectric materials. We demonstrate the antireflection property of the films on glass, cellulose acetate (CA) and polyetherimide (PEI) substrates. The films on CA and PEI retain their antireflection property after multiple bending cycles. Furthermore, films are intrinsically hydrophobic, over a wide pH range, with static contact angles up to 143 on paper and 123 on glass and CA. Producing nanoporous ormosil thin films on flexible substrates may expand their use in low cost electronic, optical devices and sensors, and lab-on-paper applications.

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“…Aerogel, an ultra-lightweight, multi-porous inorganic substance formed via 3-D gel network from which a gel-liquid is selectively removed via supercritical drying is a promising solid-sorbent for CO 2 sorption and storage [19]. SiO 2 aerogel are novel materials with characteristics of high surface area, high pore volume and low density.…”

Section: Introductionmentioning

confidence: 99%

Amine impregnated porous silica gel sorbents synthesized from water–glass precursors for CO2 capturing

Minju

Abhilash

Nair

et al. 2015

Chemical Engineering Journal

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In this work, porous silica gel-solid beads have been made from economically affordable water-glass precursors via sol-gel nano casting technique. A stable nanometric silica sol was prepared first from water glass and studied for surface potential and sol to gel transition. A free-flow, injectable gel was obtained upon aging the sol which was then assembled into spherical silica beads in a chemical bath. A surface area of 304.7 m 2 g -1 was obtained for water glass derived silica gel beads. These gel beads were impregnated with 3-aminopropyltrimethoxysilane (APTMS) and polyethylenimine (PEI) active functional groups at different percentages for turning the gel beads as sorbents for CO 2 gas adsorption. The effect of amine loading on the thermal stability, morphology as well as porosity was studied and was correlated with CO 2 adsorption values. Depending upon the amount of amine loaded in the gel support CO 2 uptake was found varied. These amine modified silica gel porous adsorbents showed CO 2 adsorption capacity at temperatures as low as 100 o C; samples modified with 15 wt% PEI had CO 2 adsorption capacity of 1.16 mmol g -1 at 50 o C.

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Silica aerogel films prepared at ambient pressure by using surface derivatization to induce reversible drying shrinkage

Cited by 438 publications

References 11 publications

Superhydrophobic and Omnidirectional Antireflective Surfaces from Nanostructured Ormosil Colloids

Superhydrophobic and Omnidirectional Antireflective Surfaces from Nanostructured Ormosil Colloids

Template free preparation of nanoporous organically modified silica thin films on flexible substrates

Amine impregnated porous silica gel sorbents synthesized from water–glass precursors for CO2 capturing

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