Synthesis of cellular inorganic materials by foaming sol-gels

Mianxue, Wu,; Fujiu, Takamitsu; Messing, Gary L.

doi:10.1016/0022-3093(90)90167-k

Cited by 83 publications

(53 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…For example, stabilized foams of freon (fluorotrichloromethane) droplets dispersed in water have been used to prepare honeycomb silica morphologies by in situ gelation of a silica sol within the boundary and interstitial spaces of the organized fluid. [28] Another strategy is to produce transitory foams by spreading a thin film of a supersaturated microemulsion onto a metal substrate and partially removing the oil phase by washing with hot hexane. This destabilizes the microemulsion film and causes microphase separation of the remaining oil and supersaturated aqueous solution into a self-organized foam- like array of submicrometer-size oil droplets surrounded by supersaturated aqueous fluid.…”

Section: Reaction Field Replicationmentioning

confidence: 99%

The Chemistry of Form

Mann

2000

Angew. Chem. Int. Ed.

638

423

View full text Add to dashboard Cite

Section: Reaction Field Replicationmentioning

confidence: 99%

The Chemistry of Form

Mann

2000

Angew. Chem. Int. Ed.

638

423

View full text Add to dashboard Cite

“…This bubble enlargement is mainly a result of coalescence and coarsening. The coalescence of neighbouring bubbles is a consequence of the displacement of liquid around neighbouring bubbles up to the point that the 5 Mayes, UK films separating them are so fine that rupture occurs. Coarsening, on the other hand, occurs due to the diffusion of gas.…”

Section: Rheology Of Suspensionsmentioning

confidence: 99%

“…The first two approaches lead mainly to porosity in the range of 2-100 nm; they are the incorporation of organic phases that are then eliminated during firing [1] and the partial sintering of ceramics [2]. The other two approaches typically produce cellular pores varying from approximately 50 μm to 5 mm; they are the replication of polymer foams by impregnation [3] or CVD coating [4] and the foaming of suspensions [5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Processing of cellular ceramics by foaming and in situ polymerisation of organic monomers

Sepúlveda

Binner

1999

Journal of the European Ceramic Society

431

220

View full text Add to dashboard Cite

“…Finally, it is likely that the local preference for high surface area noncompact structures is the cause of the observed reentrant percolating network at ultralow packing. Ultralow-density equilibrium cellular structures have potential applications as structured [32] macroporous materials. Typical lowdensity cellular materials are >10% by weight solid [32]: this phase is 10-100 times emptier.…”

mentioning

confidence: 99%

“…Ultralow-density equilibrium cellular structures have potential applications as structured [32] macroporous materials. Typical lowdensity cellular materials are >10% by weight solid [32]: this phase is 10-100 times emptier.…”

mentioning

confidence: 99%

Low-Density Ordered Phase in Brownian Dipolar Colloidal Suspensions

Agarwal

Yethiraj

2009

Phys. Rev. Lett.

View full text Add to dashboard Cite

We study the low volume fraction and electric field phase behavior of a Brownian colloidal suspension. On the application of a uniform ac field, we find a novel phase where chains of particles aggregate to form a well defined cellular network, consisting of particle-free ''voids'' surrounded by a percolating network of particle-rich walls. This cellular structure is stable to very long times, indicative of an equilibrium thermodynamic phase. The cell-cell spacing is not sensitive to the concentration of the sample but scales with sample thickness. Any self-consistent mechanism for the existence of this void phase must consist of long-ranged repulsions and shorter-ranged attractions. DOI: 10.1103/PhysRevLett.102.198301 PACS numbers: 47.57.JÀ, 64.70.pv Brownian colloidal suspensions with tunable interactions are important model systems for understanding phase transitions in atomic systems [1][2][3][4]. Real-space microscopy and light scattering experiments have been carried out on crystal nucleation dynamics [5,6] as well as structure and dynamics at the colloidal glass transition [7][8][9]. In the presence of an external electric field, Brownian colloidal spheres experience an anisotropic dipolar interaction and form chains (the ''string fluid'') and multichain aggregates [10,11], as well as body centered tetragonal (BCT) crystals [12][13][14]. Multiple competing interactions lead to richer phase behavior. In colloid-polymer mixtures both network-forming gel phases and glassy behavior can be observed by control of competing attractive and repulsive interactions [15,16]. Anisotropic interactions between colloids [17] in a liquid crystal medium also lead to a network of particle aggregates [18]. In dipolar colloids with added electrostatic repulsions, numerous crystalline phases are observed [19,20]. The dipolar interaction is of great interest because it consists of both competing on-axis (along the electric field) attractions and in-plane repulsions, and because it is an important driving force for nanoparticle selforganization [21].Simulations of spheres with both dipolar and van der Waals interactions have shown many variants (linear aggregates, droplets, columns) of phase separation into regions of higher and lower densities [22,23]. However, structure formation in the low-density regime of Brownian colloidal suspensions in an electric field has not attracted much experimental attention. Recently, interesting field induced cellular structures were reported in a granular medium [24], but the mechanism (and whether they represented equilibrium structures) was not clear.In this Letter, we report real-space confocal microscopy studies of the effect of an ac external electric field on the low-density structure of Brownian colloidal suspensions. We report the existence of a novel ''gel-like'' phase at low volume fractions ( < 4:0%) where chains of particles aggregate in time to form a cellular structure composed of ''voids''-particle-free domains enclosed completely by particle-rich walls. We propose that the co...

show abstract

Synthesis of cellular inorganic materials by foaming sol-gels

Cited by 83 publications

References 8 publications

The Chemistry of Form

The Chemistry of Form

Processing of cellular ceramics by foaming and in situ polymerisation of organic monomers

Low-Density Ordered Phase in Brownian Dipolar Colloidal Suspensions

Contact Info

Product

Resources

About