Please use this identifier to cite or link to this item: http://repositorio.unicamp.br/jspui/handle/REPOSIP/81399
Type: Artigo de periódico
Title: Poly(n-alkylsilsesquioxane)s: Synthesis, Characterization, and Modification with Poly(dimethylsiloxane)
Author: De Prado, LASA
Torriani, IL
Yoshida, IVP
Abstract: Self-supported translucent films constituted of poly(n-octylsilsesquioxane) or poly(n-dodecylsilsesquioxane) were obtained from the hydrolysis and condensation of n-octyltriethoxysilane (OTES) or n-dodecyltriethoxysi lane (DTES), respectively. Dense films were obtained in the absence of organic solvents, with dibutyltin diacetate as catalyst. These films exhibited good optical transparency and thermal stability. The incorporation of oligomeric dimethylsiloxane units (D(Me,Me)) in these materials, derived from silanol-terminated poly(dimethylsiloxane) (PDMS) or 1,1,3,3-tetramethyl-1,3-diethoxydisiloxane (TMDES), was carried out during the hydrolysis and condensation of OTES and DTES and was confirmed by solid-state (29)Si NMR. Poly(n-octylsilsesquioxane) showed a glass-transition temperature at -65 degrees C, due to the increase in the free volume, promoted by the bulky n-octyl groups. The differential scanning calorimetric (DSC) curves of the polymer derived from DTES were characterized by first-order transitions at temperatures ranging from -15.8 to -0.7 degrees C. Further studies of these networks by low-temperature XRD evidenced narrowing of the diffraction halos suggesting a partial order-disorder transition for these materials at lower temperatures. Good thermal stability up to 350 degrees C and the solvent-free production process make these polymers potential candidates for the development of self-supported hydrophobic protective coatings. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1220-1229, 2010
Subject: networks
polycondensation
polysiloxanes
SAXS
thermogravimetric analysis (TGA)
Country: EUA
Editor: John Wiley & Sons Inc
Rights: fechado
Identifier DOI: 10.1002/pola.23885
Date Issue: 2010
Appears in Collections:Unicamp - Artigos e Outros Documentos

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