Synthesis of Barium Sulfate Nanoparticles and Nanofilaments in Reverse Micelles and Microemulsions

Jeremy D. Hopwood, Stephen Mann

Research output: Contribution to journalArticle

246 Citations (Scopus)

Abstract

Supersaturated reverse micelles and microemulsions containing either AOT (sodium bis(2-ethylhexylsulfosuccinate)), C12EO4 (poly(oxyethylene-4-dodecyl ether)), or DDAB (didodecyldimethylammonium bromide) surfactants have been used as organized reaction microenvironments for barium sulfate precipitation. Nanoclusters of amorphous barium sulfate, 2-4 nm in size, were formed in association with BaNaAOT reverse micelles. In contrast, highly elongated filaments of crystalline barium sulfate, with lengths up to 100 μm and aspect ratios of 1000, were formed in BaNaAOT microemulsions. The individual filaments were single crystals of barite elongated predominantly along the [010] axis and in some instances consisted of coaligned nanofilaments, 20-50 nm in width. Similar reactions in C12EO4 reverse micelles and microemulsions afforded barite nanocrystals, 5-7 nm in dimension and tabular-shaped barite crystals, up to 400 nm in size, respectively. Rhombic crystals of barite, approximatety 200 nm in size, were deposited in DDAB microemulsions. No barite filaments were observed in the C12EO4 and DDAB systems. A generalized mechanism for the growth of barite nanofilaments in AOT microemulsions, involving the irreversible fusion, unidirectional exchange, and coalescence of microemulsion droplets, followed by crystallization of an amorphous filamentous BaSO4/surfactant phase, is described.

LanguageEnglish
Pages1819-1828
Number of pages10
JournalChemistry of Materials
Volume9
Issue number8
DOIs
Publication statusPublished - 1 Aug 1997
Externally publishedYes

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Barium Sulfate
Barite
Microemulsions
Micelles
Barium
Nanoparticles
Surface active agents
Surface-Active Agents
Crystals
Nanoclusters
Coalescence
Nanocrystals
Sulfates
Aspect ratio
Ethers
Fusion reactions
Crystallization
Sodium
Association reactions
Single crystals

Cite this

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title = "Synthesis of Barium Sulfate Nanoparticles and Nanofilaments in Reverse Micelles and Microemulsions",
abstract = "Supersaturated reverse micelles and microemulsions containing either AOT (sodium bis(2-ethylhexylsulfosuccinate)), C12EO4 (poly(oxyethylene-4-dodecyl ether)), or DDAB (didodecyldimethylammonium bromide) surfactants have been used as organized reaction microenvironments for barium sulfate precipitation. Nanoclusters of amorphous barium sulfate, 2-4 nm in size, were formed in association with BaNaAOT reverse micelles. In contrast, highly elongated filaments of crystalline barium sulfate, with lengths up to 100 μm and aspect ratios of 1000, were formed in BaNaAOT microemulsions. The individual filaments were single crystals of barite elongated predominantly along the [010] axis and in some instances consisted of coaligned nanofilaments, 20-50 nm in width. Similar reactions in C12EO4 reverse micelles and microemulsions afforded barite nanocrystals, 5-7 nm in dimension and tabular-shaped barite crystals, up to 400 nm in size, respectively. Rhombic crystals of barite, approximatety 200 nm in size, were deposited in DDAB microemulsions. No barite filaments were observed in the C12EO4 and DDAB systems. A generalized mechanism for the growth of barite nanofilaments in AOT microemulsions, involving the irreversible fusion, unidirectional exchange, and coalescence of microemulsion droplets, followed by crystallization of an amorphous filamentous BaSO4/surfactant phase, is described.",
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Synthesis of Barium Sulfate Nanoparticles and Nanofilaments in Reverse Micelles and Microemulsions. / Hopwood, Jeremy D.; Mann, Stephen.

In: Chemistry of Materials, Vol. 9, No. 8, 01.08.1997, p. 1819-1828.

Research output: Contribution to journalArticle

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