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Title: Polysilsesquioxanes through base-catalyzed redistribution of oligohydridosiloxanes

Abstract

Organopolysilsesquioxanes have recently gained much interest as materials for low-K dielectrics, ceramic precursors and photoresists. Typical sol-gel synthesis of polysilsesquioxanes involves the hydrolysis of organotricholorosilanes and/or organotrialkoxysilanes in the presence of acid or base catalysts and organic solvents. However, under sol-gel conditions most organotrialkoxysilanes do not afford silsesquioxane gels. This limits the range of organic functionalities that can be introduced into these hybrid organic-inorganic materials. An alternative route to polysilsesquioxanes is through oligohydridosiloxanes. Catalytic disproportionation, by titanium complexes, of linear or cyclic oligomers of methylhydridosiloxanes can lead to polymethylsilsesquioxanes. The authors have shown that disproportionation of oligomethylhydridosiloxanes can also be catalyzed by tetrabutylammonium hydroxide to yield polymethylsilsesquioxanes (scheme 1). This replaces the step-growth sol-gel polymerization process of organotrialkoxysilanes, which requires solvent, stoichiometric water and produces alcohol and water condensation by-products. Tetraalkylammonium hydroxides, as catalysts, are also attractive because they readily decompose by heating above 150 C; thus, they can be easily removed from the final materials. In this paper the authors report on both the catalytic and stoichiometric redistribution of organohydridosiloxanes to produce polysilsesquioxane foams and gels of the formula (RSiO{sub 1.5}){sub n} which otherwise cannot be obtained through traditional sol-gel means.

Authors:
; ; ;
Publication Date:
Research Org.:
Sandia National Labs., Albuquerque, NM (US); Sandia National Labs., Livermore, CA (US)
Sponsoring Org.:
US Department of Energy (US)
OSTI Identifier:
756093
Report Number(s):
SAND2000-1088C
TRN: AH200021%%119
DOE Contract Number:  
AC04-94AL85000
Resource Type:
Conference
Resource Relation:
Conference: Materials Research Society Meeting, San Francisco, CA (US), 04/24/2000--04/28/2000; Other Information: PBD: 1 May 2000
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; SILOXANES; SOL-GEL PROCESS; FOAMS; GELS; SYNTHESIS; ORGANIC SILICON COMPOUNDS; ORGANIC POLYMERS; CATALYSTS

Citation Formats

RAHIMIAN,KAMYAR, ASSINK,ROGER A., LANG,DAVID P., and LOY,DOUGLAS A. Polysilsesquioxanes through base-catalyzed redistribution of oligohydridosiloxanes. United States: N. p., 2000. Web.
RAHIMIAN,KAMYAR, ASSINK,ROGER A., LANG,DAVID P., & LOY,DOUGLAS A. Polysilsesquioxanes through base-catalyzed redistribution of oligohydridosiloxanes. United States.
RAHIMIAN,KAMYAR, ASSINK,ROGER A., LANG,DAVID P., and LOY,DOUGLAS A. Mon . "Polysilsesquioxanes through base-catalyzed redistribution of oligohydridosiloxanes". United States. https://www.osti.gov/servlets/purl/756093.
@article{osti_756093,
title = {Polysilsesquioxanes through base-catalyzed redistribution of oligohydridosiloxanes},
author = {RAHIMIAN,KAMYAR and ASSINK,ROGER A. and LANG,DAVID P. and LOY,DOUGLAS A.},
abstractNote = {Organopolysilsesquioxanes have recently gained much interest as materials for low-K dielectrics, ceramic precursors and photoresists. Typical sol-gel synthesis of polysilsesquioxanes involves the hydrolysis of organotricholorosilanes and/or organotrialkoxysilanes in the presence of acid or base catalysts and organic solvents. However, under sol-gel conditions most organotrialkoxysilanes do not afford silsesquioxane gels. This limits the range of organic functionalities that can be introduced into these hybrid organic-inorganic materials. An alternative route to polysilsesquioxanes is through oligohydridosiloxanes. Catalytic disproportionation, by titanium complexes, of linear or cyclic oligomers of methylhydridosiloxanes can lead to polymethylsilsesquioxanes. The authors have shown that disproportionation of oligomethylhydridosiloxanes can also be catalyzed by tetrabutylammonium hydroxide to yield polymethylsilsesquioxanes (scheme 1). This replaces the step-growth sol-gel polymerization process of organotrialkoxysilanes, which requires solvent, stoichiometric water and produces alcohol and water condensation by-products. Tetraalkylammonium hydroxides, as catalysts, are also attractive because they readily decompose by heating above 150 C; thus, they can be easily removed from the final materials. In this paper the authors report on both the catalytic and stoichiometric redistribution of organohydridosiloxanes to produce polysilsesquioxane foams and gels of the formula (RSiO{sub 1.5}){sub n} which otherwise cannot be obtained through traditional sol-gel means.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2000},
month = {5}
}

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