Photoluminescence of Bridged Silsesquioxanes Containing Urea or Urethane Groups with Nanostructures Generated by the Competition between the Rates of Self-Assembly of Organic Domains and the Inorganic Polycondensation

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dc.contributor.author Fasce, Diana P.
dc.contributor.author J. Williams, Roberto J.
dc.contributor.author Matejka, Libor
dc.contributor.author Pleštil, Josef
dc.contributor.author Brus, Jirí
dc.contributor.author Serrano Prieto, Berna
dc.contributor.author Cabanelas Valcárcel, Juan Carlos
dc.contributor.author Baselga Llidó, Juan
dc.date.accessioned 2017-12-04T10:42:23Z
dc.date.available 2017-12-04T10:42:23Z
dc.date.issued 2006-04-27
dc.identifier.bibliographicCitation Fasce, D. P:, J. Williams, R. J., Matejka, L., Pleštil, J., Brus, J., Serrano, B., Cabanelas, J. C. & Baselga, J. (2006). Photoluminescence of Bridged Silsesquioxanes Containing Urea or Urethane Groups with Nanostructures Generated by the Competition between the Rates of Self-Assembly of Organic Domains and the Inorganic Polycondensation. Macromolecules, 39 (11), pp. 3794-3801.
dc.identifier.issn 0024-9297
dc.identifier.uri http://hdl.handle.net/10016/26027
dc.description.abstract The aim of this study was to investigate the changes produced in the nanostructures and the photoluminescence spectra of bridged silsesquioxanes containing urea or urethane groups, by varying the relative rates between the self-assembly of organic domains and the inorganic polycondensation. Precursors of the bridged silsesquioxanes were 4,4‘-[1,3-phenylenebis(1-methylethylidene)]bis(aniline) and 4,4‘-isopropylidenediphenol, end-capped with 3-isocyanatopropyltriethoxysilane. The inorganic polycondensation was produced using either high or low formic acid concentrations, leading to transparent films with different nanostructures as revealed by FTIR, SAXS, and ²⁹Si NMR spectra. For the bridged silsesquioxanes containing urea groups the self-assembly of organic domains was much faster than the inorganic polycondensation for both formic acid concentrations. However, the arrangement was more regular and the short-range order higher when the rate of inorganic polycondensation was lower. The photoluminescence spectra of the most ordered structures revealed the presence of two main processes:  radiative recombinations in inorganic clusters and photoinduced proton-transfer generating NH₂⁺ and N⁻ defects and their subsequent radiative recombination. In the less-ordered urea-bridged silsesquioxanes a third process was present assigned to a photoinduced proton transfer in H-bonds exhibiting a broad range of strengths. For urethane-bridged silsesquioxanes the driving force for the self-assembly of organic bridges was lower than for urea-bridged silsesquioxanes. When the synthesis was performed with a high formic acid concentration, self-assembled structures were not produced. Instead, large inorganic domains composed of small inorganic clusters were generated. Self-assembly of organic domains took place only when employing low polycondensation rates. For both materials the photoluminescence was mainly due to radiative processes within inorganic clusters and varied significantly with their state of aggregation.
dc.description.sponsorship The financial support of the National Research Council (CONICET, Argentina), the National Agency for the Promotion of Science and Technology (ANPCyT, Argentina, PICT 14738-03), the University of Mar del Plata, the Grant Agency of the Czech Republic (Project 203/05/2252), and Project Nanoter (Project MAT2004/01347, MEC-DGI, Spain) is gratefully acknowledged. INTEMA and the Institute of Macromolecular Chemistry acknowledge the support of the European Network of Excellence Nanofun-Poly for the diffusion of their research results.
dc.format.extent 8
dc.format.mimetype application/pdf
dc.language.iso eng
dc.publisher American Chemical Society (ACS)
dc.rights © American Chemical Society, 2006
dc.title Photoluminescence of Bridged Silsesquioxanes Containing Urea or Urethane Groups with Nanostructures Generated by the Competition between the Rates of Self-Assembly of Organic Domains and the Inorganic Polycondensation
dc.type article
dc.subject.eciencia Materiales
dc.identifier.doi https://doi.org/10.1021/ma052105y
dc.rights.accessRights openAccess
dc.relation.projectID Gobierno de España. MAT2004/01347
dc.type.version acceptedVersion
dc.identifier.publicationfirstpage 3794
dc.identifier.publicationissue 11
dc.identifier.publicationlastpage 3801
dc.identifier.publicationtitle Macromolecules
dc.identifier.publicationvolume 39
dc.identifier.uxxi AR/0000002764
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