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Structural evolution of silica sols modified with formamide

Detalhes bibliográficos
Autor(a) principal: Lenza,R.F.S.
Data de Publicação: 2001
Outros Autores: Vasconcelos,W.L.
Tipo de documento: Artigo
Idioma: eng
Título da fonte: Materials research (São Carlos. Online)
Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392001000300006
Resumo: In this work we investigated the influence of formamide on the acid-catalyzed sol-gel process by Fourier transform infrared spectroscopy (FTIR). Three silica sols were studied: Sol catalyzed with nitric acid without formamide, sol catalyzed with nitric acid containing formamide and sol catalyzed with a mixture of nitric acid and hydrofluoric acid and modified with formamide. Following the time evolution of both the Si-(OH) stretching vibration at around 950 cm-1 and the Si-O-(Si) vibration between 1040 cm-1 and 1200 cm-1 we were able to describe the structural evolution of each sol. The curve of evolution of Si-(OH) stretching vibration corresponding to sol A has a simple asymptotic evolution. In the case of formamide containing sol, we observed a two-step structural evolution indicating that for the system containing formamide the polymerization goes through a temporary stabilization of oligomers, which can explain the non-variation of the Si-O(H) bond wavenumber for a certain time. Gelation times were of several days for gels without formamide and few hours for gels containing additive. The presence of additive resulted in a highly interconnected gel.
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spelling Structural evolution of silica sols modified with formamidesol-gelformamideFTIRstructural evolutionIn this work we investigated the influence of formamide on the acid-catalyzed sol-gel process by Fourier transform infrared spectroscopy (FTIR). Three silica sols were studied: Sol catalyzed with nitric acid without formamide, sol catalyzed with nitric acid containing formamide and sol catalyzed with a mixture of nitric acid and hydrofluoric acid and modified with formamide. Following the time evolution of both the Si-(OH) stretching vibration at around 950 cm-1 and the Si-O-(Si) vibration between 1040 cm-1 and 1200 cm-1 we were able to describe the structural evolution of each sol. The curve of evolution of Si-(OH) stretching vibration corresponding to sol A has a simple asymptotic evolution. In the case of formamide containing sol, we observed a two-step structural evolution indicating that for the system containing formamide the polymerization goes through a temporary stabilization of oligomers, which can explain the non-variation of the Si-O(H) bond wavenumber for a certain time. Gelation times were of several days for gels without formamide and few hours for gels containing additive. The presence of additive resulted in a highly interconnected gel.ABM, ABC, ABPol2001-07-01info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersiontext/htmlhttp://old.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392001000300006Materials Research v.4 n.3 2001reponame:Materials research (São Carlos. Online)instname:Universidade Federal de São Carlos (UFSCAR)instacron:ABM ABC ABPOL10.1590/S1516-14392001000300006info:eu-repo/semantics/openAccessLenza,R.F.S.Vasconcelos,W.L.eng2001-08-23T00:00:00Zoai:scielo:S1516-14392001000300006Revistahttp://www.scielo.br/mrPUBhttps://old.scielo.br/oai/scielo-oai.phpdedz@power.ufscar.br1980-53731516-1439opendoar:2001-08-23T00:00Materials research (São Carlos. Online) - Universidade Federal de São Carlos (UFSCAR)false
dc.title.none.fl_str_mv Structural evolution of silica sols modified with formamide
title Structural evolution of silica sols modified with formamide
spellingShingle Structural evolution of silica sols modified with formamide
Lenza,R.F.S.
sol-gel
formamide
FTIR
structural evolution
title_short Structural evolution of silica sols modified with formamide
title_full Structural evolution of silica sols modified with formamide
title_fullStr Structural evolution of silica sols modified with formamide
title_full_unstemmed Structural evolution of silica sols modified with formamide
title_sort Structural evolution of silica sols modified with formamide
author Lenza,R.F.S.
author_facet Lenza,R.F.S.
Vasconcelos,W.L.
author_role author
author2 Vasconcelos,W.L.
author2_role author
dc.contributor.author.fl_str_mv Lenza,R.F.S.
Vasconcelos,W.L.
dc.subject.por.fl_str_mv sol-gel
formamide
FTIR
structural evolution
topic sol-gel
formamide
FTIR
structural evolution
description In this work we investigated the influence of formamide on the acid-catalyzed sol-gel process by Fourier transform infrared spectroscopy (FTIR). Three silica sols were studied: Sol catalyzed with nitric acid without formamide, sol catalyzed with nitric acid containing formamide and sol catalyzed with a mixture of nitric acid and hydrofluoric acid and modified with formamide. Following the time evolution of both the Si-(OH) stretching vibration at around 950 cm-1 and the Si-O-(Si) vibration between 1040 cm-1 and 1200 cm-1 we were able to describe the structural evolution of each sol. The curve of evolution of Si-(OH) stretching vibration corresponding to sol A has a simple asymptotic evolution. In the case of formamide containing sol, we observed a two-step structural evolution indicating that for the system containing formamide the polymerization goes through a temporary stabilization of oligomers, which can explain the non-variation of the Si-O(H) bond wavenumber for a certain time. Gelation times were of several days for gels without formamide and few hours for gels containing additive. The presence of additive resulted in a highly interconnected gel.
publishDate 2001
dc.date.none.fl_str_mv 2001-07-01
dc.type.driver.fl_str_mv info:eu-repo/semantics/article
dc.type.status.fl_str_mv info:eu-repo/semantics/publishedVersion
format article
status_str publishedVersion
dc.identifier.uri.fl_str_mv http://old.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392001000300006
url http://old.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392001000300006
dc.language.iso.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv 10.1590/S1516-14392001000300006
dc.rights.driver.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv text/html
dc.publisher.none.fl_str_mv ABM, ABC, ABPol
publisher.none.fl_str_mv ABM, ABC, ABPol
dc.source.none.fl_str_mv Materials Research v.4 n.3 2001
reponame:Materials research (São Carlos. Online)
instname:Universidade Federal de São Carlos (UFSCAR)
instacron:ABM ABC ABPOL
instname_str Universidade Federal de São Carlos (UFSCAR)
instacron_str ABM ABC ABPOL
institution ABM ABC ABPOL
reponame_str Materials research (São Carlos. Online)
collection Materials research (São Carlos. Online)
repository.name.fl_str_mv Materials research (São Carlos. Online) - Universidade Federal de São Carlos (UFSCAR)
repository.mail.fl_str_mv dedz@power.ufscar.br
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