Influence of the alkoxide group, solvent, catalyst, and concentration on the gelation and porosity of hexylene-bridged polysilsesquioxanes

Douglas A Loy, Kimberly A. Obrey-Defriend, Kennard V. Wilson, McKenzie Minke, Brigitta M. Baugher, Colleen R. Baugher, Duane A. Schneider, Gregory M. Jamison, Kenneth J. Shea

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

1,6-Hexylene-bridged polysilsesquioxanes are hybrid organic-inorganic materials prepared by sol-gel polymerization of 1,6-bis(trialkoxysilyl)hexanes. Due to the trialkoxysilyl groups bonded to each end of the hexylene bridging group, hydrolysis and condensation easily gave network polymers in the form of gels. When the solvent evaporates from the gels, dry gels or xerogels are obtained that may be non-porous or porous depending on whether the network is compliant enough to resist collapse or not. Hexylene-bridged materials appear to lie on the boundary between polysilsesquioxanes with bridging groups that are sufficiently long and flexible to allow porosity to collapse with drying and those with bridging groups that are short and stiff enough to prevent collapse of porosity during drying. Under base-catalyzed conditions, 1,6- bis(triethoxysilyl)hexane polymerizes to yield porous xerogels while under acidic conditions, non-porous xerogels are obtained. In this study, we examine the effects of the alkoxide group on the sol-gel process and the resulting xerogels' porosity and provide a more detailed examination of the relative importance of the sol-gel reaction parameters (concentration, pH, solvent). 1, 6-Bis(trimethoxysilyl)hexane (1), 1,6-bis(triethoxysilyl)hexane (2), and 1, 6-bis(tri-n-propoxysilyl)hexane (3) were polymerized under acidic and basic conditions in methanol, ethanol, or n-propanol, respectively, as well as tetrahydrofuran (THF). The resulting gels were dried to provide xerogels that were characterized by SEM, solid state 13C and 29Si Cross Polarization Magic Angle Spinning (CP MAS) NMR spectroscopy, and nitrogen and carbon dioxide sorption porosimetry.

Original languageEnglish (US)
Pages (from-to)82-94
Number of pages13
JournalJournal of Non-Crystalline Solids
Volume362
Issue number1
DOIs
StatePublished - 2013

Fingerprint

Xerogels
alkoxides
gelation
Gelation
Hexane
xerogels
Hexanes
Porosity
gels
porosity
catalysts
Gels
Catalysts
Sol-gels
Drying
drying
Nitrogen Dioxide
1-Propanol
Magic angle spinning
Propanol

Keywords

  • Gelation
  • Hexylene-bridged
  • Polysilsesquioxanes
  • Porosity
  • Sol-gel

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Ceramics and Composites
  • Electronic, Optical and Magnetic Materials
  • Materials Chemistry

Cite this

Influence of the alkoxide group, solvent, catalyst, and concentration on the gelation and porosity of hexylene-bridged polysilsesquioxanes. / Loy, Douglas A; Obrey-Defriend, Kimberly A.; Wilson, Kennard V.; Minke, McKenzie; Baugher, Brigitta M.; Baugher, Colleen R.; Schneider, Duane A.; Jamison, Gregory M.; Shea, Kenneth J.

In: Journal of Non-Crystalline Solids, Vol. 362, No. 1, 2013, p. 82-94.

Research output: Contribution to journalArticle

Loy, Douglas A ; Obrey-Defriend, Kimberly A. ; Wilson, Kennard V. ; Minke, McKenzie ; Baugher, Brigitta M. ; Baugher, Colleen R. ; Schneider, Duane A. ; Jamison, Gregory M. ; Shea, Kenneth J. / Influence of the alkoxide group, solvent, catalyst, and concentration on the gelation and porosity of hexylene-bridged polysilsesquioxanes. In: Journal of Non-Crystalline Solids. 2013 ; Vol. 362, No. 1. pp. 82-94.
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AU - Wilson, Kennard V.

AU - Minke, McKenzie

AU - Baugher, Brigitta M.

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N2 - 1,6-Hexylene-bridged polysilsesquioxanes are hybrid organic-inorganic materials prepared by sol-gel polymerization of 1,6-bis(trialkoxysilyl)hexanes. Due to the trialkoxysilyl groups bonded to each end of the hexylene bridging group, hydrolysis and condensation easily gave network polymers in the form of gels. When the solvent evaporates from the gels, dry gels or xerogels are obtained that may be non-porous or porous depending on whether the network is compliant enough to resist collapse or not. Hexylene-bridged materials appear to lie on the boundary between polysilsesquioxanes with bridging groups that are sufficiently long and flexible to allow porosity to collapse with drying and those with bridging groups that are short and stiff enough to prevent collapse of porosity during drying. Under base-catalyzed conditions, 1,6- bis(triethoxysilyl)hexane polymerizes to yield porous xerogels while under acidic conditions, non-porous xerogels are obtained. In this study, we examine the effects of the alkoxide group on the sol-gel process and the resulting xerogels' porosity and provide a more detailed examination of the relative importance of the sol-gel reaction parameters (concentration, pH, solvent). 1, 6-Bis(trimethoxysilyl)hexane (1), 1,6-bis(triethoxysilyl)hexane (2), and 1, 6-bis(tri-n-propoxysilyl)hexane (3) were polymerized under acidic and basic conditions in methanol, ethanol, or n-propanol, respectively, as well as tetrahydrofuran (THF). The resulting gels were dried to provide xerogels that were characterized by SEM, solid state 13C and 29Si Cross Polarization Magic Angle Spinning (CP MAS) NMR spectroscopy, and nitrogen and carbon dioxide sorption porosimetry.

AB - 1,6-Hexylene-bridged polysilsesquioxanes are hybrid organic-inorganic materials prepared by sol-gel polymerization of 1,6-bis(trialkoxysilyl)hexanes. Due to the trialkoxysilyl groups bonded to each end of the hexylene bridging group, hydrolysis and condensation easily gave network polymers in the form of gels. When the solvent evaporates from the gels, dry gels or xerogels are obtained that may be non-porous or porous depending on whether the network is compliant enough to resist collapse or not. Hexylene-bridged materials appear to lie on the boundary between polysilsesquioxanes with bridging groups that are sufficiently long and flexible to allow porosity to collapse with drying and those with bridging groups that are short and stiff enough to prevent collapse of porosity during drying. Under base-catalyzed conditions, 1,6- bis(triethoxysilyl)hexane polymerizes to yield porous xerogels while under acidic conditions, non-porous xerogels are obtained. In this study, we examine the effects of the alkoxide group on the sol-gel process and the resulting xerogels' porosity and provide a more detailed examination of the relative importance of the sol-gel reaction parameters (concentration, pH, solvent). 1, 6-Bis(trimethoxysilyl)hexane (1), 1,6-bis(triethoxysilyl)hexane (2), and 1, 6-bis(tri-n-propoxysilyl)hexane (3) were polymerized under acidic and basic conditions in methanol, ethanol, or n-propanol, respectively, as well as tetrahydrofuran (THF). The resulting gels were dried to provide xerogels that were characterized by SEM, solid state 13C and 29Si Cross Polarization Magic Angle Spinning (CP MAS) NMR spectroscopy, and nitrogen and carbon dioxide sorption porosimetry.

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