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Bacterial cellulose-silica organic-inorganic hybrids

Barud, H. S.; Assuncao, R. M. N.; Martines, M. A. U.; Dexpert-Ghys, J.; Marques, R. F. C.; Messaddeq, Y.; Ribeiro, S. J. L.
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica Formato: 363-367
ENG
Relevância na Pesquisa
96.43%
Bacterial cellulose (BC) hydrated membranes present nanometric reticulated structure that can be used as a template in the preparation of new organic-inorganic hybrids. BC-silica hybrids were prepared from BC membranes and tetraethoxysilane, (TEOS) at neutral pH conditions at room temperature. Macroscopically homogeneous membranes were obtained containing up to 66 wt.% of silica spheres, 20-30 nm diameter. Scanning electron micrographs clearly show the silica spheres attached to cellulose microfibrils. By removing the cellulose, the silica spheres can be easily recovered. The new hybrids are stable up to 300 degrees C and display a broad emission band under UV excitation assigned to oxygen-related defects at the silica particles surface. Emission color can be tuned by changing the excitation wavelength.

Waveguides and gratings fabrication in zirconium-based organic/inorganic hybrids

Vicente, Carlos M. S.; Pecoraro, Édison; Ferreira, Rute A. S.; Andre, Paulo S.; Nogueira, Rogerio; Messaddeq, Younes; Ribeiro, Sidney J. L.; Carlos, Luis D.
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica Formato: 80-85
ENG
Relevância na Pesquisa
86.4%
Sol-gel derived poly(oxyethylene)/siloxane organic/inorganic di-ureasil hybrids containing different amounts of methacrylic acid (McOH, CH(2)=C(CH(3))COOH)) modified zirconium oxo-clusters (Zr-OMc) were processed as thin films deposited in glassy substrates via spin coating and as transparent and shape controlled monoliths. Channel monomode waveguides and diffraction gratings were UV patterned using the Talbot interferometer and the Lloyd mirror interferometer experimental setups. The time dependence of the diffraction gratings efficiency was studied for hybrids containing different amounts of Zr-OMc. Finally, the number of propagating modes and the refractive index gradient within the waveguide region, determined as a Gaussian section located below the patterned channel, was evaluated and modeled, a maximum index contrast of 2.43 X 10(-5) being estimated.

Enhanced emission from Eu(III) beta-diketone complex combined with ether-type oxygen atoms of di-ureasil organic-inorganic hybrids

Molina, C.; Dahmouche, K.; Messaddeq, Y.; Ribeiro, SJL; Silva, MAP; Bermudez, V. D.; Carlos, L. D.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 93-101
ENG
Relevância na Pesquisa
96.39%
Organic-inorganic hybrids, named di-ureasils and described by polyether-based chains grafted to both ends to a siliceous backbone through urea cross linkages, were used as hosts for incorporation of the well-known coordination complex of trivalent europium (Eu3+) ions described by the formula [Eu(TTA)(3)(H2O)(2)] (where TTA stands for thenoyltrifluoroacetone). By comparing with Eu3+-doped di-ureasil without complex form the new materials prepared here enhanced the quantum efficiency for photoemission of Eu3+ ions. The enhancement can be explained by the coordination ability of the organic counterpart of the host structure which is strong enough to displace water molecules in [Eu(TTA)(3)(H2O)(2)] from the rare earth neighbourhood after the incorporation process. High intensity of Eu3+ emission was observed with a low non-radiative decay rate under ultraviolet excitation. The quantum efficiency calculated from the decay of D-5(0) emission was 74%, which in the same range of values previously obtained for the most efficient Eu3+ coordination compounds reported in literature. Luminescence, X-ray absorption and infrared absorption results considered together leads to a picture where the first coordination shell of Eu3+ is composed of the 6 oxygen atoms of the 3 beta-diketonate ligands and 2 ether-like oxygen atoms of the host. (C) 2003 Elsevier B.V. B.V. All rights reserved.

Distributed feedback multipeak laser emission in Rhodamine 6G doped organic-inorganic hybrids

Oliveira, D. C.; Messaddeq, Y.; Dahmouche, K.; Ribeiro, S. J. L.; Goncalves, R. R.; Vesperini, A.; Gindre, D.; Nunzi, J. -M.
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica Formato: 359-363
ENG
Relevância na Pesquisa
86.3%
Organic-inorganic hybrid materials were prepared from an ureasil precursor (ureapropyltriethoxysilane designated as UPTES) and acrylic acid modified zirconium (IV) n-propoxide. Thin films containing rhodamine 6G (Rh6G) were prepared by spin-coating on glass substrates with different Zr:Si molar ratios (Zr:Si = 75:25, 50:50 and 25:75). Refractive index, thickness, number of propagating modes and attenuation coefficient were measured at 543.5, 632.8 and 1550 nm wavelengths by the prism coupling technique. Distributed feedback (DFB) laser effect was observed and studied as a function of films thickness and refractive index.

Eu3+ doped polyphosphate-aminosilane organic-inorganic hybrids

Dias, F. A.; Ribeiro, SJL; Goncalves, R. R.; Messaddeq, Y.; Carlos, L. D.; Bermudez, V. D.; Rocha, J.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 74-78
ENG
Relevância na Pesquisa
76.3%
The preparation and characterization of new Eu3+ doped polyphosphate-aminosilane hybrids xerogels is reported. Eu3+ D-5(0) emission quantum efficiency ranges from 0.41 to 0.54 depending on the SUP ratio. These rather high values are due to the substitution of phosphate and amino groups for water in the Eu3+ coordination shell. Raman and Si-29 and C-13 CP-MAS NMR results suggest that no strong interaction exists between the polyphosphate and the siloxane parts. Not fully condensed siloxane colloidal domains seem to be homogeneously distributed in the polyphosphate network. Good optical quality and favorable Eu3+ spectroscopic characteristics suggest these new hybrids as good hosts for lanthanide ions in optical devices. (C) 2003 Published by Elsevier B.V.

Photoluminescence of bulks and thin films of Eu3+-doped organic/inorganic hybrids

Pecoraro, Édison; Ferreira, R. A. Sa; Molina, C.; Ribeiro, S. J. L.; Messsaddeq, Y.; Carlos, L. D.
Fonte: Elsevier B.V. Sa Publicador: Elsevier B.V. Sa
Tipo: Artigo de Revista Científica Formato: 136-139
ENG
Relevância na Pesquisa
96.36%
Organic-inorganic hybrids formed by polyether-based chains grafted to both ends to a siliceous backbone through urea cross-linkages (-NHC=O)NH-), named di-ureasil, have been used as host for incorporation of Eu3+ in the form of EuCl3. The bulks and the thin films, both optically transparent, were characterized by excitation, absorption and emission spectroscopy. Photoluminescence results point out that the Eu3+ ions occupy, at least, two distinct local environments. Besides, the processing method (thin films or bulks) has influence on the energy levels of the hybrid host probably due to the lower degree of organization of the thin films structure. (c) 2007 Elsevier B.V. All rights reserved.

Waveguide features in self-patternable amine functionalized organic-inorganic hybrids

Sá Ferreira, R. A.; André, P. S.; Nogueira, R.; Vicente, C.; Macedo, A. G.; Maia, L. J Q; Carlos, L. D.; Ribeiro, S. J L
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Conferência ou Objeto de Conferência Formato: 462-465
ENG
Relevância na Pesquisa
96.45%
We report the use of organic-inorganic sol-gel derived poly(oxyehylene)/ siloxane hybrid doped with methacrylic acid modified zirconium (IV) n-propoxide for the fabrication of low cost waveguides trough direct UV laser writing. The organic-inorganic hybrids were processed as monoliths with size and shape control. The effective guiding region was identified and the number of modes was estimated via mode field analyses. A grating was successfully superimposed on the channel and the respective reflection spectrum was measured, enabling the determination of the guiding region dimension, the calculation of the effective refractive index of the guided mode. © 2007 IEEE.

Structure and kinetics of formation of APTS/GPTS-derived organic/inorganic hybrids

Awano, Carlos M.; Donatti, Dario A.; De Vicente, Fabio S.; Vollet, Dimas R.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 17839-17844
ENG
Relevância na Pesquisa
96.36%
The structure and the kinetics of formation of APTS/GPTS-derived organic/inorganic hybrids were studied in situ by small-angle-X-ray scattering. The data were interpreted in terms of a process of primary particles formation and growth of mass-fractal clusters. At the very early stage, the population of the nonfractal primary particles (D = 3) increases with time. As the mass-fractal clusters appear (D < 3) as a result of the aggregation process, the radius of gyration, Rg, of the clusters increases on average. At advanced stages of aggregation, the clusters grow in a mechanism in which the number of particles per clusters increases while the number of clusters diminishes with time, in such a way that the correlation volume of the clusters, Vc, fulfills the relationship Vc â̂ R g D, in agreement with a mass-fractal character of the clusters. These results supporting a cluster-cluster aggregation process, together with the typically very low value found for the mass-fractal dimension D, are in favor of a diffusion-controlled cluster aggregation mechanism. © 2013 American Chemical Society.

UV laser photofabrication of waveguide couplers using self-patterning organic-inorganic hybrids

Xavier, Lionnel R.; Fernandes, Vasco R.; Vicente, Carlos M. S.; Pecoraro, Édison; Carlos, Luis D.; Ferreira, Rute A. S.; André, Paulo S.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 2304-2307
ENG
Relevância na Pesquisa
96.36%
Planar waveguides with controlled refractive index were produced using thin films of sol-gel derived organic-inorganic hybrids, so called di-ureasils. Spectroscopic ellipsometry was used to characterize the films thickness and refractive index. UV-laser direct-writing method was used to produce Y-splitter structures with coupling ratio of 50% without the need of photoinitiators.

Optical filters and resonant cavities based on di-ureasil organic–inorganic hybrids

Vicente, Carlos Miguel Santos; Ferreira, Rute Amorim Sá; Pecoraro, Édison; André , Paulo Sergio de Brito; Carlos, Luís Dias
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 475-479
ENG
Relevância na Pesquisa
86.36%
Sol–gel derived poly(oxyethylene)/siloxane organic–inorganic di-ureasil hybrids containing different amounts (20–60% mol) of methacrylic acid (McOH) modified zirconium oxo-clusters (Zr-OMc) were processed as thin films and transparent and shape controlled monoliths. Laser direct writing was used to create channel waveguides, Bragg gratings, Fabry–Perot cavities and optical filters. The resulting Fabry–Perot optical cavity displays a free spectral range of 16.55 GHz and a fringe intensity contrast of 5.35 dB. Optical rejection values between 6.7 and 10.4 dB were obtained by varying the amount of the Zr-OMc oxo-clusters.

Avaliação de revestimentos hibridos organo-inorganicos e de resinas polissiloxanas aplicadas sobre aço galvanizado e sobre camadas de Zn-Fe; Organic-inorganic hybrid coatings and polysiloxanes resins for corrosion protection of galvanized steel and electroplated ZnFe steel

Maria Eliziane Pires de Souza
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 23/02/2006 PT
Relevância na Pesquisa
76.3%
As características protetoras das superfícies de aços galvanizados são geralmente intensificadas através da passivação por cromo hexavalente (Cr+6). Porém, por ser este um elemento tóxico, vários estudos visando a substituição do procedimento de cromatização vêm sendo realizados. As resinas de polissiloxanos e materiais híbridos organo-inorgânicos preparados pelo processo sol-gel, podem vir a ser um excelente substituinte ao processo de cromatização. Neste trabalho, filmes híbridos organo-inorgânico e filmes de silicone foram aplicados em aço galvanizado e em camadas de Zn-Fe. Os revestimentos foram então avaliados através de Espectroscopia de Impedância Eletroquímica. Os dados obtidos pela Espectroscopia foram modelados através de um circuito equivalente, permitindo a obtenção dos parâmetros eletroquímicos para os sistemas avaliados. Além disso, o potencial em circuito aberto, para os diferentes sistemas, foi monitorado durante processo de desgaste em sistema pino-disco em solução de NaCI 3%. Os revestimentos foram comparados em termos de resistência à corrosão e coeficiente de fricção. Os resultados mostram um bom desempenho para os revestimentos como protetores de corrosão e o comportamento destes mostraram-se dependente do tipo de revestimento metálico que foi aplicado no aço.; Chromating pre-treatments have been widely used to improve galvanized steel corrosion resistance. However...

Organic-inorganic hybrid coatings for corrosion protection of galvanized steel and electroplated ZnFe steel

Souza, M. E. P.; Ariza, E.; Ballester, M.; Yoshida, I. V. P.; Rocha, L. A.; Freire, C. M. A.
Fonte: Associação Brasileira de Metalurgia e Materiais [etc.] Publicador: Associação Brasileira de Metalurgia e Materiais [etc.]
Tipo: Artigo de Revista Científica
Publicado em /05/2005 ENG
Relevância na Pesquisa
76.32%
The development of hybrids materials by the sol-gel process has been extensively investigated in recent years. The combination a wide variety of compositions and production processes had permit the use of these materials in different applications like coatings for corrosion protection of metals and abrasion resistant coatings. In this work organic-inorganic hybrid materials have been prepared from the hydrolysis of tetraethylorthosilicate (TEOS) and silanol-terminated polidymetilmetoxysilane (PDMS) using a sol-gel process. The composition evaluated was 50% TEOS- 50% PDMS. These materials have been applied on galvanized steel and on steel electroplated with a ZnFe alloy. In order to evaluate the degradation behaviour of these coatings, electrochemical techniques were used. They consisting in the monitoring of the open-circuit potential (Ecorr), and in the realization of potentiodynamic polarization measurements of the samples, which was performed in a 3% NaCl aqueous solution. Additionally, electrochemical impedance spectroscopy (EIS) was used as a complementary technique for the evaluation of the corrosion mechanisms of the coating system. The surface of the samples, before and after the electrochemical tests, have been inspected by SEM and EDS. EIS data was fitted to an equivalent circuit from which the electrochemical parameters were obtained. Results show a good protective character of the hybrid films...

Organic-inorganic hybrid coatings for corrosion protection of galvanized steel and electroplated znfe steel

Souza, M. E. P.; Ariza, E.; Ballester, M.; Yoshida, I. V. P.; Rocha, L. A.; Freire, C. M. A.
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em //2004 ENG
Relevância na Pesquisa
76.32%
The development of hybrids materials by the sol-gel process has been extensively investigated in recent years. The combination a wide variety of compositions and production processes had permit the use of these aterials in different applications like coatings for corrosion protection of metals and abrasion resistant coatings. In this work organic-inorganic hybrid materials have been prepared from the hydrolysis of tetraethylorthosilicate (TEOS) and silanol-terminated polidymetilmetoxysilane (PDMS) using a sol-gel process. The composition evaluated was 50% TEOS- 50% PDMS. These materials have been applied on galvanized steel and on steel electroplated with a ZnFe alloy. In order to evaluate the degradation behaviour of these coatings, electrochemical techniques were used. They consisting in the monitoring of the open-circuit potential (Ecorr), and in the realization of potentiodynamic polarization measurements of the samples, which was performed in a 3% NaCl aqueous solution. Additionally, electrochemical impedance spectroscopy (EIS) was used as a complementary technique for the evaluation of the corrosion mechanisms of the coating system. The surface of the samples, before and after the electrochemical tests, have been inspected by SEM and EDS. EIS data was fitted to an equivalent circuit from which the lectrochemical parameters were obtained. Results show a good protective character of the hybrid films...

Preparation and characterization of novel highly omniphobic cellulose fibers organic-inorganic hybrid materials

Cunha, Ana G.; Freire, Carmen S.R.; Silvestre, Armando J.D.; Neto, Carlos Pascoal Neto; Gandini, Alessandro
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
76.33%
This paper reports the preparation of class-II organic-inorganic hybrid materials by the heterogeneous chemical modification of cellulose fibers with (3-isocyanatopropyl)triethoxysilane, followed by the acid hydrolysis (and condensation) of the appended siloxane moieties as such, and in the presence of either tetraethoxysilane or 1H,1H,2H,2H-perfluorodecyltriethoxysilane. These modifications produced an inorganic "coating" around the fibers, while preserving their ultrastructure, as confirmed by XRD and SEM. The detailed characterization of these new hybrid materials by FTIR and (29)Si NMR showed that, upon hydrolysis of the ethoxy groups, condensation reactions took place leading mainly to Si-O-Si linear sequences, followed by a smaller contribution of more branched moieties, and that a significant amount of OH groups were also formed, which gave rise to hydrophilic surfaces. The hybrids obtained by hydrolysis in the presence of 1H,1H,2H,2H-perfluorodecyltriethoxysilane displayed a very pronounced hydrophobic and lipophobic character (reaching contact angles with water and diiodomethane as high as 140 degrees and 134 degrees, respectively), due to the presence of the perfluorinated moieties. (C) 2010 Elsevier Ltd. All rights reserved.; FCT - SFRH/BD/31134/2006; FCT - National Program for Scientific re-equipment; Rede/1509/RME/2005; REEQ/515/CTM/2005

UV laser photofabrication of waveguide couplers using self-patterning organic-inorganic hybrids

Xavier, Lionnel R.; Fernandes, Vasco R.; Vicente, Carlos M. S.; Pecoraro, Edison; Carlos, Luis D.; Ferreira, Rute A. S.; Andre, Paulo S.
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
96.36%
Planar waveguides with controlled refractive index were produced using thin films of sol-gel derived organic inorganic hybrids, so called di-ureasils. Spectroscopic ellipsometry was used to characterize the films thickness and refractive index. UV-laser direct-writing method was used to produce Y-splitter structures with coupling ratio of 50 % without the need of photoinitiators. (C) 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2304-2307, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26256

Optical filters and resonant cavities based on di-ureasil organic-inorganic hybrids

Vicente, C. M. S.; Ferreira, R. A. S.; Pecoraro, E.; Andre, P. S.; Carlos, L. D.
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
86.36%
Sol-gel derived poly(oxyethylene)/siloxane organic-inorganic di-ureasil hybrids containing different amounts (20-60% mol) of methacrylic acid (McOH) modified zirconium oxo-clusters (Zr-OMc) were processed as thin films and transparent and shape controlled monoliths. Laser direct writing was used to create channel waveguides, Bragg gratings, Fabry-Perot cavities and optical filters. The resulting Fabry-Perot optical cavity displays a free spectral range of 16.55 GHz and a fringe intensity contrast of 5.35 dB. Optical rejection values between 6.7 and 10.4 dB were obtained by varying the amount of the Zr-OMc oxo-clusters.

Thin film optimization design of organic-inorganic hybrids for waveguide high-rejection optical filters

Vicente, Carlos M. S.; Venkatachaam, Ramkanna; Ferreira, Bruno M.; Marques, Paulo G.; Marques, Carlos A. F.; Pecoraro, Edison; Carlos, Luis D.; André, Paulo S.; Ferreira, Rute A. S.
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
96.47%
We report the fabrication of transparent, low surface roughness (<0.1 nm), and low-loss (1.5 +/- 0.2 dB cm (1), 532 nm) thin films of organic-inorganic hybrids with controlled refractive index values stable under aging. High-rejection optical filters based on first-order Bragg gratings inscribed in channel waveguides were fabricated using UV-laser writing. Their high-rejection figure of merit (similar to 24 dB) is the best value found until now for organic inorganic hybrids reinforcing the potential of sol gel technology in the integration of optoelectronic components based on hybrid materials, namely in the fabrication of cost-effective integrated optics devices. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Synthesis and characterization of organic-inorganic hybrids formed between conducting polymers and crystalline antimonic acid

Beleze,Fábio A.; Zarbin,Aldo J. G.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2001 EN
Relevância na Pesquisa
76.3%
In this paper we report the synthesis and characterization of novel organic-inorganic hybrid materials between the crystalline antimonic acid (CAA) and two conductive polymers: polypyrrole and polyaniline. The hybrids were obtained by in situ oxidative polymerization of monomers by the Sb(V) present in the pyrochlore-like CAA structure. The materials were characterized by infrared and Raman spectroscopy, X-ray diffraction, cyclic voltammetry, CHN elemental analysis and electronic paramagnetic resonance spectroscopy. The results showed that both polymers were formed in their oxidized form, with the CAA structure acting as a counter anion.

Characterization of organic-inorganic hybrid coatings for corrosion protection of galvanized steel and electroplated ZnFe steel

Souza,Maria Eliziane Pires de; Ariza,Edith; Ballester,Margarita; Yoshida,Inez Valéria Pagotto; Rocha,Luis Augusto; Freire,Célia Marina de Alvarenga
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2006 EN
Relevância na Pesquisa
76.3%
The development of hybrids materials has been extensively investigated in recent years. The combination of a wide variety of compositions and production processes had permitted the use of these materials in different applications like coatings for corrosion protection of metals. In this work organic-inorganic hybrid materials have been prepared from the hydrolysis of tetraethylorthosilicate and silanol-terminated polidymetilmetoxysilane using a sol-gel process. These materials have been applied on galvanized steel and on steel electroplated with a ZnFe. In order to evaluate the degradation behavior of these coatings, electrochemical techniques (Electrochemical Impedance Spectroscopy and Potentiodynamic Polarization) were used. EIS data was fitted to an equivalent circuit from which the electrochemical parameters were obtained. Results show a good protective character of the hybrid films, when compared with uncovered specimens. The overall performance of the coating systems appears to be highly dependent on the kind of metallic coating applied to the steel.

PWA-diureasils organic-inorganic hybrids: photochromism and effect of the organic chain length

Obara, P. A.; Sarmento, V. H. V.; Ribeiro, S. J. L.; Nalin, M.; Molina, C.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 64-69
ENG
Relevância na Pesquisa
76.33%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Processo FAPESP: 2012/02708-8; Di-ureasil organic-inorganic hybrids have been used together with Phosphotungstic acid (PWA- H3PW12O40) in the preparation of new photochromic materials. PWA was incorporated in different relative concentrations in di-ureasils displaying different organic chain lengths. The structure and photochromic behaviour of these novel material were investigated by means of infrared (FTIR), photoluminescence (PL) and Ultraviolet-Visible (UV-Vis) spectroscopies and Small Angle X-ray Scattering (SAXS) technique as a function of PWA content and also of the polymer chain length. Eu3+ has been incorporated as probe ion. For the short polymer chains, europium and PWA keggin structures are located close to oxygen in the ether type of the polyoxides segments and for the long polymer chain carbonyl groups of the urea units were observed to contribute in the coordination. Moreover, the photochromic effect was followed by UV-Vis measurements which showed that in both hybrid families changing from colorless to blue after UV exposure, and the bleaching process, depend directly on the polymer chain length and the nature of the sites where PWA are coordinated in the matrix. (C) 2015 Elsevier B.V. All rights reserved.