Carbon dioxide mediated synthesis of mesoporous silica films: Tuning properties using pressure

Xinxin Li, Bryan Vogt

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

Mesoporous silica films were synthesized by the selective condensation of tetraethylorthosilicate (TEOS) within preformed amphiphilic templates using carbon dioxide as a carrier for the precursor. Blends of poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (Pluronic F108) and poly(p-hydroxystyrene) (PHOSt) containing p-toluenesulfonic acid were exposed to gaseous or supercritical fluid solutions of CO2, TEOS, and H 2O at 60 °C. The subsequent sorption within the polymeric template delivered the precursors for selective reaction in the hydrophilic domains. Mesoporous silica films were formed by the removal of the template by calcination at 450 °C. The physical properties of mesoporous silica were tailored through control of the CO2 pressure during the reaction. The pore size increased slightly (1.6-1.81 nm) as the CO2 pressure was increased to 80 bar. A small increase in pressure resulted in a significant expansion of the pore size near 84 bar to nearly 4 nm pore radii. In addition to tuning the mesopore size, increasing the CO2 pressure during synthesis led to a decrease in the apparent reaction rate and subsequently an increase in the film porosity. Moreover, the apparent accessibility of the mesopores to small molecules as evidenced by the lack of capillary condensation of water and toluene was tuned by the CO2 pressure. Synthesis very near the critical pressure of CO2 resulted in a small fraction of the pores being accessible. Thus, synthesis of mesoporous films using CO 2 appears to be a promising route to limit the contamination of low-k dielectric materials for microelectronics applications.

Original languageEnglish (US)
Pages (from-to)3229-3238
Number of pages10
JournalChemistry of Materials
Volume20
Issue number9
DOIs
StatePublished - May 13 2008

Fingerprint

Carbon Dioxide
Silicon Dioxide
Carbon dioxide
Tuning
Silica
Polyethylene oxides
Pore size
Condensation
Polypropylene oxides
Poloxamer
Supercritical fluids
Toluene
Carbon Monoxide
Microelectronics
Calcination
Reaction rates
Sorption
Contamination
Physical properties
Porosity

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

Cite this

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abstract = "Mesoporous silica films were synthesized by the selective condensation of tetraethylorthosilicate (TEOS) within preformed amphiphilic templates using carbon dioxide as a carrier for the precursor. Blends of poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (Pluronic F108) and poly(p-hydroxystyrene) (PHOSt) containing p-toluenesulfonic acid were exposed to gaseous or supercritical fluid solutions of CO2, TEOS, and H 2O at 60 °C. The subsequent sorption within the polymeric template delivered the precursors for selective reaction in the hydrophilic domains. Mesoporous silica films were formed by the removal of the template by calcination at 450 °C. The physical properties of mesoporous silica were tailored through control of the CO2 pressure during the reaction. The pore size increased slightly (1.6-1.81 nm) as the CO2 pressure was increased to 80 bar. A small increase in pressure resulted in a significant expansion of the pore size near 84 bar to nearly 4 nm pore radii. In addition to tuning the mesopore size, increasing the CO2 pressure during synthesis led to a decrease in the apparent reaction rate and subsequently an increase in the film porosity. Moreover, the apparent accessibility of the mesopores to small molecules as evidenced by the lack of capillary condensation of water and toluene was tuned by the CO2 pressure. Synthesis very near the critical pressure of CO2 resulted in a small fraction of the pores being accessible. Thus, synthesis of mesoporous films using CO 2 appears to be a promising route to limit the contamination of low-k dielectric materials for microelectronics applications.",
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Carbon dioxide mediated synthesis of mesoporous silica films : Tuning properties using pressure. / Li, Xinxin; Vogt, Bryan.

In: Chemistry of Materials, Vol. 20, No. 9, 13.05.2008, p. 3229-3238.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Carbon dioxide mediated synthesis of mesoporous silica films

T2 - Tuning properties using pressure

AU - Li, Xinxin

AU - Vogt, Bryan

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AB - Mesoporous silica films were synthesized by the selective condensation of tetraethylorthosilicate (TEOS) within preformed amphiphilic templates using carbon dioxide as a carrier for the precursor. Blends of poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (Pluronic F108) and poly(p-hydroxystyrene) (PHOSt) containing p-toluenesulfonic acid were exposed to gaseous or supercritical fluid solutions of CO2, TEOS, and H 2O at 60 °C. The subsequent sorption within the polymeric template delivered the precursors for selective reaction in the hydrophilic domains. Mesoporous silica films were formed by the removal of the template by calcination at 450 °C. The physical properties of mesoporous silica were tailored through control of the CO2 pressure during the reaction. The pore size increased slightly (1.6-1.81 nm) as the CO2 pressure was increased to 80 bar. A small increase in pressure resulted in a significant expansion of the pore size near 84 bar to nearly 4 nm pore radii. In addition to tuning the mesopore size, increasing the CO2 pressure during synthesis led to a decrease in the apparent reaction rate and subsequently an increase in the film porosity. Moreover, the apparent accessibility of the mesopores to small molecules as evidenced by the lack of capillary condensation of water and toluene was tuned by the CO2 pressure. Synthesis very near the critical pressure of CO2 resulted in a small fraction of the pores being accessible. Thus, synthesis of mesoporous films using CO 2 appears to be a promising route to limit the contamination of low-k dielectric materials for microelectronics applications.

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