Oxidic Aerogels

Baumann, Theodore F.; Gash, Alexander E.; Fox, Glenn A.; and, Joe H. Satcher Jr.; Hrubesh, Lawrence W.

doi:10.1002/9783527618286.ch26a

Cited by 17 publications

(20 citation statements)

References 123 publications

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“…In addition, the interactions between the membrane components and the supporting surface could also be enhanced by modifying the aerogel/xerogel composition with cytosolic-borne species so the underlying foundation for the membranes could be made protein-friendly or cytosol-mimetic. The compositions may be controlled such that organic, inorganic, or biologically active components can be embedded in bulk or modified on the surface. ,− This is one of the most important characteristics to explore in order to fully realize the value of an aerogel/xerogel as a membrane support.…”

Section: Discussionmentioning

confidence: 99%

“…Since their discovery by Kistler in the early 1930s, aerogels have found a wide range of applications because of their unique physical and chemical properties. , Silica aerogels are typically prepared by the sol−gel process, and the solvent is removed after gelation under supercritical conditions, which preserves the tenuous solid network. An aerogel dried by supercritical carbon dioxide is hydrophilic, similar to silicon oxide, but also permeable with extraordinarily high porosity (up to 99.8%), unlike glass . The preparation of a xerogel differs only in the solvent removal step in which the liquid part of the alcogel is removed by evaporation .…”

Section: Introductionmentioning

confidence: 99%

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Fluid Biomembranes Supported on Nanoporous Aerogel/Xerogel Substrates

et al. 2004

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Planar supported lipid bilayers have attracted immense interest for their properties as model cell membranes and for potential applications in biosensors and lab-on-a-chip devices. We report the formation of fluid planar biomembranes on hydrophilic silica aerogels and xerogels. Scanning electron microscopy results showed the presence of interconnected silica beads of approximately 10-25 nm in diameter and nanoscale open pores of comparable size for the aerogel and grain size of approximately 36-104 nm with approximately 9-24 nm diameter pores for the xerogel. When the aerogel/xerogel was prehydrated and then allowed to incubate in l-alpha-phosphatidylcholine (egg yolk PC) unilamellar vesicle (approximately 30 nm diameter) solution, lipid bilayers were formed due to the favorable interaction of vesicles with the hydroxyl-abundant silica surface. Lateral mobility of labeled lipid N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)-1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine was retained in the membranes. A diffusion coefficient of 0.61 +/- 0.22 microm(2)/s was determined from fluorescence recovery after photobleaching analysis for membranes on aerogels, compared to 2.46 +/- 0.35 microm(2)/s on flat glass. Quartz crystal microbalance-dissipation was utilized to monitor the kinetics of the irreversible adsorption and fusion of vesicles into bilayers on xerogel thin films.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Fluid Biomembranes Supported on Nanoporous Aerogel/Xerogel Substrates

et al. 2004

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“…Aerogels have several distinct and uncommon properties that make them attractive for technical applications in many areas. − They possess high porosity (90−99%), high surface area, low density, some degree of optical transparency, and low thermal conductivity. Their unique properties are a result of their unusual microstructure, which consists of a continuous network of colloidal particles, or polymeric chains with characteristic diameters of ∼10 nm, open porosity, and characteristic pore diameters less than 100 nm.…”

Section: Introductionmentioning

confidence: 99%

“…Their unique properties are a result of their unusual microstructure, which consists of a continuous network of colloidal particles, or polymeric chains with characteristic diameters of ∼10 nm, open porosity, and characteristic pore diameters less than 100 nm. Aerogels have been studied for application as thermal insulators, catalysts, dielectrics, optical coatings, laser targets, waste remediation materials, sensors, pesticides, energetic materials, and collectors for high-energy particles …”

Section: Introductionmentioning

confidence: 99%

Strong Akaganeite Aerogel Monoliths Using Epoxides: Synthesis and Characterization

2003

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The synthesis of iron(III) oxide aerogel monoliths was performed by adding any one of several different 1,2- and 1,3-epoxides to ethanolic Fe(III) salt solutions at room temperature. While all of the epoxides examined resulted in gel formation, robust low-density (∼30−40 kg/m3; 99% porous), high-surface-area (∼250−300 m2/g), aerogel monoliths were prepared by the addition of 1,3-epoxide derivatives to solutions of FeCl3·6H2O, followed by drying with supercritical CO2. Both types of iron(III) oxide aerogels (those made with 1,2- and 1,3-epoxides respectively) were characterized using elemental analysis, X-ray diffraction, thermal analysis, acoustic measurements, transmission electron microscopy, scanning electron microscopy, and N2 adsorption desorption analysis. Elemental analyses and powder X-ray diffraction indicated that the strong aerogel monoliths made with the 1,3-epoxides are made up predominately of polycrystalline β-FeOOH, akaganeite, and those made with the 1,2-epoxides are amorphous. To our knowledge, this is first known report of synthesis and characterization of akaganeite aerogel materials. Transmission electron microscopy analysis indicates that aerogels derived using 1,3-epoxides have a microstructure made up of a highly reticulated network of fibers with diameters from ∼5 to 35 nm and lengths several times that, whereas those resulting from the use of 1,2-epoxides consist of interconnected spherical particles, whose diameters are 5−15 nm. The difference in microstructure results in each type of aerogel displaying very distinct physical and mechanical properties. In particular, the stiffness of the β-FeOOH aerogels is remarkable for a transition metal oxide aerogel. Monolithic cylinders of β-FeOOH aerogel can be sintered at 515 °C, transforming to α-Fe2O3 without shattering.

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“…The SnO 2 aerogel was prepared based on a general epoxide-initiated gelation method recently developed in our laboratory. [13] In this approach, the epoxide acts as an acid scavenger in the sol±gel polymerization reaction, driving the hydrolysis and condensation of the hydrated metal species.…”

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confidence: 99%