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Titolo:
HYBRID SILICA-GELS CONTAINING 1,3-BUTADIYNE BRIDGING UNITS - THERMAL AND CHEMICAL-REACTIVITY OF THE ORGANIC FRAGMENT
Autore:
CORRIU RJP; MOREAU JJE; THEPOT P; MAN MWC;
Indirizzi:
UNIV MONTPELLIER 2,DEPT CHIM ORGAN FINE,CNRS UMR44,CASE COURRIER 007 F-34095 MONTPELLIER 05 FRANCE
Titolo Testata:
Chemistry of materials
fascicolo: 1, volume: 8, anno: 1996,
pagine: 100 - 106
SICI:
0897-4756(1996)8:1<100:HSC1BU>2.0.ZU;2-1
Fonte:
ISI
Lingua:
ENG
Soggetto:
DIACETYLENE) SEGMENTED COPOLYMERS; OPTICAL-PROPERTIES; CROSS-LINKING; POLYMERS; BEHAVIOR; POLY)(SILYLENE)DIACETYLENES>; PYROLYSIS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
50
Recensione:
Indirizzi per estratti:
Citazione:
R.J.P. Corriu et al., "HYBRID SILICA-GELS CONTAINING 1,3-BUTADIYNE BRIDGING UNITS - THERMAL AND CHEMICAL-REACTIVITY OF THE ORGANIC FRAGMENT", Chemistry of materials, 8(1), 1996, pp. 100-106

Abstract

Silica gel containing diyne units have been obtained from molecular organosilicon precursors and the properties associated to the very reactive unsaturated organic moieties have been explored. The sol-gel polymerization of 1,4-bis(trimethoxysilyl)-1,3-butadiyne ((MeO)(3)SiC=CC=CSi(OMe)(3)) quantitatively led to a silsesquioxane network, [O-1.5-SiC=CC=CSiO1.5](n), consisting of siloxanes chains with bridging diyne units. The derived xerogels were characterized by IR and C-13 and Si-29 CP MAS NMR spectroscopies. The major environment of the Si atom corresponded to a T-2 CSi(OR)(OSi)(2) substructure, and only minor Si-C bondcleavage occurred during the sol-gel condensation. The chemical reactivity of the hybrid organic-inorganic gel was studied and used as a tool for the study of the organization of the solid induced by the organic moieties. Upon heating, in the solid state, the diyne fragments undergo a polyaddition to give an ene-yne structure. The polymerization, observed in the solid state, suggests favorable arrangements of the organic fragments within the amorphous solid. The resulting composite material consists in a network made of interpenetrating ene-yne and siloxane polymers. On the other hand, the organic diyne fragments in the hybrid gel have been removed, leaving silica behind, in two ways: (i) The thermal oxidation in air led to microporous silicas with N-2 BET surface areas in the range 300-350 m(2) (g-1) (ii) Interestingly, the smooth Si-C bond cleavage by MeOH catalyzed by NH4F gave highly porous silica with N-2 BET surface areas up to 950 m(2) g(-1) The latter elimination of the organic moiety under mild reaction conditions is of particular interest since it gives rise to silica with a surface area significantly higher than that produced upon thermal oxidation and higher than that of the originating hybrid precursor.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 29/09/20 alle ore 19:04:21