Preparation and characterization of phenyl-, benzyl-, and phenethyl-substituted polysilsesquioxanes

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Polysilsesquioxanes are a class of siloxane polymers commonly prepared by the hydrolysis and condensation of trialkoxysilanes or trichlorosilanes. From a trifunctional monomer one would expect the organically-modified polymers to be highly crosslinked and insoluble resins. However, while some silsesquioxane monomers with R = H, CH{sub 3}, or vinyl do form crosslinked polymers capable of forming gels, the majority react to form soluble oligosilsesquioxanes, including discrete polyhedral oligomers, and polymers. Because of their solubility, ladder structures have been proposed. However, viscosity studies by Frye indicate that the polyphenylsilsesquioxane is more likely best represented by a polymer rich in both cyclic structures ... continued below

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4 p.

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Schneider, D.A.; Loy, D.A.; Baugher, B.M.; Wheeler, D.R.; Assink, R.A.; Alam, T.M. et al. September 1, 1998.

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  • Sandia National Laboratories
    Publisher Info: Sandia National Labs., Albuquerque, NM (United States)
    Place of Publication: Albuquerque, New Mexico

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Description

Polysilsesquioxanes are a class of siloxane polymers commonly prepared by the hydrolysis and condensation of trialkoxysilanes or trichlorosilanes. From a trifunctional monomer one would expect the organically-modified polymers to be highly crosslinked and insoluble resins. However, while some silsesquioxane monomers with R = H, CH{sub 3}, or vinyl do form crosslinked polymers capable of forming gels, the majority react to form soluble oligosilsesquioxanes, including discrete polyhedral oligomers, and polymers. Because of their solubility, ladder structures have been proposed. However, viscosity studies by Frye indicate that the polyphenylsilsesquioxane is more likely best represented by a polymer rich in both cyclic structures and branches, but without any regular stereochemistry. In this study, the authors have examined the hydrolysis and condensation polymerizations of phenyltrialkoxysilane, benzyltrialkoxysilane, and 2-phenethyltrialkoxysilane monomers under both acidic and basic conditions. The resulting phenyl, benzyl and phenethyl-substituted polysilsesquioxanes were characterized by {sup 1}H, {sup 13}C, {sup 29}Si NMR, gel permeation chromatography, and differential scanning calorimetry. The effects of the organic substituent (phenyl, benzyl, phenethyl), alkoxide group (OMe, OEt), catalyst (HCl, NaOH), monomer concentration, and polymer processing on polymer molecular weight and glass transition temperature were determined.

Physical Description

4 p.

Notes

OSTI as DE98005900

Source

  • 216. national American Chemical Society (ACS) meeting, Boston, MA (United States), 23-27 Aug 1998

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  • Other: DE98005900
  • Report No.: SAND--98-1400C
  • Report No.: CONF-980812--
  • Grant Number: AC04-94AL85000
  • DOI: 10.2172/658253 | External Link
  • Office of Scientific & Technical Information Report Number: 658253
  • Archival Resource Key: ark:/67531/metadc710936

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  • September 1, 1998

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  • Sept. 12, 2015, 6:31 a.m.

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  • April 13, 2016, 5:37 p.m.

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Schneider, D.A.; Loy, D.A.; Baugher, B.M.; Wheeler, D.R.; Assink, R.A.; Alam, T.M. et al. Preparation and characterization of phenyl-, benzyl-, and phenethyl-substituted polysilsesquioxanes, report, September 1, 1998; Albuquerque, New Mexico. (digital.library.unt.edu/ark:/67531/metadc710936/: accessed December 16, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.