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Highly ordered "defect-free" self-assembled hybrid films with a tetragonal mesostructure

Falcaro, Paolo and Costacurta, Stefano and Mattei, Giovanni and Amenitsch, Heinz and Marcelli, Augusto Claudio and Guidi Cestelli, Mariangela and Piccinini, Massimo and Nucara, Alessandro and Malfatti, Luca and Kidchob, Tongjit and Innocenzi, Plinio (2005) Highly ordered "defect-free" self-assembled hybrid films with a tetragonal mesostructure. Journal of the American Chemical Society, Vol. 127 (11), p. 3838-3846. eISSN 1520-5126. Article.

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DOI: 10.1021/ja0427956

Abstract

One-pot self-assembled hybrid films were synthesized by the cohydrolysis of methyltriethoxysilane and tetraethoxysilane and deposited via dip-coating. The films show a high "defect-free" mesophase organization that extends throughout the film thickness and for domains of a micrometer scale, as shown by scanning transmission electron microscopy. We have defined these films defect-free to describe the high degree of order that is achieved without defects in the pore organization, such as dislocations of pores or stacking faults. A novel mesophase, which is tetragonal I4/mmm (space group), is observed in the films. This phase evolves but retains the same symmetry throughout a wide range of temperatures of calcination. The thermal stability and the structural changes as a function of the calcination temperature have been studied by small-angle X-ray scattering, scanning transmission electron microscopy, and Fourier transform infrared spectroscopy. In situ Fourier transform infrared spectroscopy employing synchrotron radiation has been used to study the kinetics of film formation during the deposition. The experiments have shown that the slower kinetics of silica species can explain the high degree of organization of the mesostructure.

Item Type:Article
ID Code:1280
Status:Published
Refereed:Yes
Uncontrolled Keywords:Fourier Transform Infrared spectroscopy, kinetics of film formation, MTES-TEOS system
Subjects:Area 09 - Ingegneria industriale e dell'informazione > ING-IND/22 Scienza e tecnologia dei materiali
Divisions:001 Università di Sassari > 01 Dipartimenti > Architettura e pianificazione
Publisher:American Chemical Society
eISSN:1520-5126
Deposited On:18 Aug 2009 10:04

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