Making Nanoscale Materials with Supercritical Fluids

Johnston, Keith P.; Shah, Parag S.

doi:10.1126/science.1093951

Cited by 192 publications

(138 citation statements)

References 9 publications

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“…SCFs are also penetrating and versatile wetting agents by virtue of their zero surface tension and low viscosity. [19] SCFs additionally offer the opportunity to tune continuously properties such as viscosity and density, through changes in temperature and pressure.…”

mentioning

confidence: 99%

Continuous Flow Supercritical Chemical Fluid Deposition of Optoelectronic Quality CdS

Yang¹,

Hyde²,

Wilson³

et al. 2009

Advanced Materials

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mentioning

confidence: 99%

Continuous Flow Supercritical Chemical Fluid Deposition of Optoelectronic Quality CdS

Yang¹,

Hyde²,

Wilson³

et al. 2009

Advanced Materials

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“…Recent efforts [193][194][195] have successfully demonstrated that nanocellular foams and monoliths can be generated from block copolymers synthesized with fluorinated blocks and selectively swollen with scCO 2 . Watkins and co-workers [196] and Johnston and Shah [197] have shown that such swollen materials can be infused with a reactive ceramic precursor (e.g., a silicon alkoxide) to yield a templated mesoporous silicate (Fig. 13).…”

Section: Cells CM à3mentioning

confidence: 99%

Thermodynamics and Kinetic Processes of Polymer Blends and Block Copolymers in the Presence of Pressurized Carbon Dioxide

2008

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Environmentally‐responsible materials processing is becoming an important global consideration in a wide variety of technologies, especially those wherein volatile and/or residual organic solvents cannot be tolerated. In this context, polymer processing has benefited tremendously from advances achieved using high‐pressure CO2 as a viscosity modifier, plasticizing agent, foaming agent, and reaction medium. Pressurized CO2 is environmentally benign, inexpensive, sustainable, and versatile owing to its gas‐like viscosity and liquid‐like solubility, which can be tuned through judicious choice of temperature and pressure. The addition of high‐pressure CO2 to homopolymer blends and block copolymers can have a profound impact on polymer thermodynamics and kinetic processes since the number of interacting species increases. As a result, the compressibility as well as plasticization and intermolecular screening effects become non‐negligible. In this work, we review how these factors influence such polymeric systems, and discuss commercial polymer processes and applications that benefit from the use of high‐pressure CO2.

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“…The inherent mesopores of aerogel and the macropores among the disoriented fibers are especially promising for the stationary phase in liquid chromatography, because these pores make it feasible for faster separation and lower pressure drop [29,30]. For preparing the monolithic columns, two features of a supercritical fluid (SCF), among others [31,32] (Fig. 1, where scCO 2 is compared with heptanes because of their similar solvent power), thus providing better ''wetting'' into porous structures to facilitate nanostructure formation and preventing shrinkage upon drying [32,33].…”

Section: Introductionmentioning

confidence: 99%

Preparing titania aerogel monolithic chromatography columns using supercritical carbon dioxide

Sui

Liu

Lajoie

et al. 2010

J of Separation Science

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The search for a method to fabricate monolithic inorganic columns has attracted significant recent attention due to their unique ability in separation applications of various biomolecules. Silica and polymer based monolithic columns have been prepared, but titania and other metal oxide monoliths have been elusive, primarily due to their fragility. This article describes a new approach for preparing nanostructured titania based columns, which offer better performance over conventional particle packed columns for separating a wide variety of biomolecules including phosphopeptides. TiO(2) monolithic aerogels were synthesized in separation columns using in situ sol-gel reactions in supercritical carbon dioxide (scCO(2)) followed by calcination, and compared to those prepared in heptanes. The characterization results show that scCO(2) is a better solvent for the sol-gel reactions, providing lower shrinkage with the anatase TiO(2) monolith composed of nanofibers with very high surface areas. The monolithic columns show the ability to isolate phosphopeptides with little flow resistance compared to conventional titania particle based microcolumns.

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Making Nanoscale Materials with Supercritical Fluids

Cited by 192 publications

References 9 publications

Continuous Flow Supercritical Chemical Fluid Deposition of Optoelectronic Quality CdS

Continuous Flow Supercritical Chemical Fluid Deposition of Optoelectronic Quality CdS

Thermodynamics and Kinetic Processes of Polymer Blends and Block Copolymers in the Presence of Pressurized Carbon Dioxide

Preparing titania aerogel monolithic chromatography columns using supercritical carbon dioxide

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