Structural development during deformation of polyurethane containing polyhedral oligomeric silsesquioxanes (POSS) molecules

B. X. Fu, B. S. Hsiao, S. Pagola, P. Stephens, H. White, M. Rafailovich, J. Sokolov, P. T. Mather, H. G. Jeon, S. Phillips, J. Lichtenhan, J. Schwab

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265 Scopus citations

Abstract

A unique polyurethane (PU) elastomer containing inorganic polyhedral oligomeric silsesquioxane (POSS) molecules as molecular reinforcements in the hard segment was investigated by means of wide-angle X-ray diffraction (WAXD), small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) techniques. The mechanical properties of POSS modified polyurethane (POSS-PU) were also compared to those of polyurethane without POSS. The crystal structures of two different POSS molecules were first determined by X-ray powder diffraction analysis, yielding a rhombohedral cell with a = 11.57 Å, α = 95.5̊ for octacyclohexyl-POSS (1,3,5,7,9,11,13,15-octacyclohexylpentacyclo[9.5.1.13,9.15,15.17,13] octasiloxane) and a = 11.53 Å, α = 95.3° for hydrido-POSS (1-[hydridodimethylsiloxy]-3,5,7,9,11,13,15-heptacyclohexylpentacyclo [9.5.1.13,9.15,15.17,13] octasiloxane). WAXD results showed that reflection peaks distinct to POSS crystal diffraction were seen in POSS-modified polyurethane, which suggests that POSS molecules formed nanoscale crystals in the hard domain. During deformation, the average size of POSS crystals in POSS-PU was found to decrease while elongation-induced crystallization of the soft segments was observed at strains greater than 100%. The SAXS results showed microphase structure typical of segmented polyurethanes, with an initial long spacing of 110 A between the domains. At high strains, the average length of strain-induced microfibrillar soft-segment crystals was estimated to be about 60 A by SAXS. The TEM analysis of highly stretched samples showed a preferred orientation of deformed hard domains perpendicular to the stretching direction, indicating the destruction of hard segment domains by strain.

Original languageEnglish (US)
Pages (from-to)599-611
Number of pages13
JournalPolymer
Volume42
Issue number2
DOIs
StatePublished - Jan 1 2001

Keywords

  • Nanocomposites
  • Polyhedral oligomeric silsesquioxane
  • Polyurethane

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Materials Chemistry

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    Fu, B. X., Hsiao, B. S., Pagola, S., Stephens, P., White, H., Rafailovich, M., Sokolov, J., Mather, P. T., Jeon, H. G., Phillips, S., Lichtenhan, J., & Schwab, J. (2001). Structural development during deformation of polyurethane containing polyhedral oligomeric silsesquioxanes (POSS) molecules. Polymer, 42(2), 599-611. https://doi.org/10.1016/S0032-3861(00)00389-X