Preparation, characterization and photochromic behavior of phosphotungstic acid-ormosil nanocomposites

Autor(es)

Ferreira-Neto, Elias P. ^[1] ; Ullah, Sajjad ^{[2, 1]} ; de Carvalho, Flavio L. S. ^[1] ; de Souza, Adriano L. ^[1] ; de Oliveira, Jr., Marcos ^[3] ; Schneider, Jose F. ^[3] ; Mascarenhas, Yvonne P. ^[3] ; Jorge, Jr., Alberto M. ^{[4, 5, 6]} ; Rodrigues-Filho, Ubirajara P. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Quim Sao Paulo, Sao Carlos, SP - Brazil

^[2] Univ Peshawar, Inst Chem Sci, Peshawar 25120, Kpk - Pakistan

^[3] Univ Sao Paulo, Inst Fis Sao Carlos, Sao Carlos, SP - Brazil

^[4] Univ Fed Sao Carlos, Dept Engn Mat, Lab Caracterizacao Estrutural, BR-13565905 Sao Carlos, SP - Brazil

^[5] SIMAP, F-38402 St Martin Dheres - France

^[6] CNRS, LEPMI Labs, INPG UJF, UMR 5266, F-38402 St Martin Dheres - France

• Tipo de documento: Artigo Científico
• Fonte: Materials Chemistry and Physics; v. 153, p. 410-421, MAR 1 2015.
• Citações Web of Science: 11

Resumo

Reversible UV-dose-dependent photochromic materials consisting of ormosil hybrid networks doped with phosphotungstic acid (HPW) have been obtained by sol gel method. Tetraethyl orthosilicate (TEOS) and (3-glycidyloxypropyl)trimethoxysilane (GLYMO) were used as matrix-forming precursors while aminopropyltriethoxysilane (APTS) and 4-(Triethoxysilyl) butyronitrile (BuTS) as matrix-modifiers. The samples were characterized by XRD, FTIR, TEM, solid-state NMR, Raman spectroscopy, X-ray fluorescence spectroscopy and UV-Vis spectroscopy. The organic functionalities of ormosils (aminopropyl and butyronitrile groups) influence both the structure and photochromic behavior of these hybrid ormosil materials. Due to alkylammonium-phosphotungstate ion-pair formation (-NHI3+center dot PW12O403-), APTS induces incorporation of higher amount of phosphotungstate in the dip-coated films leading to higher photochromic response of these films compared to the BuTS-bearing ones. On the contrary, in drop-casted films with the same phosphotungstate content, the photochromic response is the same for BuTS- and APTS-containing ormosil films. However, the bleaching time required for re-oxidation of the reduced phosphotungstate is longer in APTS-based ormosil films than BuTS-based ones. The photochromic response of both kind of films decreases upon dehydration of the films suggesting the importance of the presence of water in the photochromic behavior of these films. The UV sensitivity, bleaching time and dehydration sensitivity of the ormosils can be tuned varying the matrix modifier nitrogenated silanes. (C) 2015 Elsevier B.V. All rights reserved. (AU)

• Processo FAPESP: 13/24948-3 - Fixação de CO2 por Nanoparticulas de SiO2@TiO2 decoradas com Ferrocianeto de Ferro (Azul da Prússia) e Ferrocianeto de Rutênio: Uma Possível Alternativa para o aumento de Sustentabilidade de Biorefinarias e Plantas de Síntese de Amônia
• Beneficiário: Elias Paiva Ferreira Neto
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 11/08120-0 - Filmes nanoestruturados: impacto da arquitetura dos filmes contendo nanopartículas e fosfotungstato sobre as propriedades fotoativas
• Beneficiário: Ubirajara Pereira Rodrigues Filho
• Modalidade de apoio: Auxílio à Pesquisa - Regular