Navegando por Palavras-chave "PPV"

Agora exibindo 1 - 6 de 6
  • Nenhuma Miniatura disponível
    Item
    Somente Metadadados
    Block copolymers of o-PPV organized at the molecular scale as Langmuir and Langmuir-Blodgett films
    (Elsevier B.V., 2014-08-01) Ferreira, Gabriel Cervoni [UNIFESP]; Caseli, Luciano [UNIFESP]; Peres, Laura Oliveira [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    The control over the molecular architecture of polymeric films can be useful to enhance the properties of polymeric devices. in this paper, poly(o-phenylene vinylene) was spread on the air-water interface in order to form stable Langmuir monolayers. These films were investigated with measurements of surface pressure, surface potential, and polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS). They were transferred from the air-water interface to solid supports through the Langmuir-Blodgett (LB) technique, and characterized with PM-IRRAS and atomic force microscopy, with the viability of the film as an optical device investigated with fluorescence spectroscopy. the immobilization of polymeric chains on solid supports as LB films may provide a high control of their molecular properties, which may enable such molecular architecture to be applied as an optoelectronic device. (C) 2014 Elsevier B.V. All rights reserved.
  • Nenhuma Miniatura disponível
    Item
    Somente Metadadados
    Controlling the luminescence properties of poly(p-phenylene vinylene) entrapped in Langmuir and Langmuir-Blodgett films of stearic acid
    (Elsevier B.V., 2011-08-01) Sakai, Andrei [UNIFESP]; Wang, Shu H.; Peres, Laura O. [UNIFESP]; Caseli, Luciano [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Universidade de São Paulo (USP)
    Properties of hybrid films can be enhanced if their molecular architecture is controlled. in this paper, poly (p-phenylene vinylene) was mixed with stearic acid in order to form stable hybrid Langmuir monolayers. Surface properties of these films were investigated with measurements of surface pressure, and also with polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS). the films were transferred from the air-water interface to solid supports through the Langmuir-Blodgett technique, and the viability of the film as optical device was investigated with fluorescence spectroscopy. Comparing the fluorescent spectra for the polymer in solution, as a casting film, and as an LB film, the emission bands for LB films were narrower and appeared at lower wavelengths. the interactions between the film components and the design for the LB film may take advantage of the method to immobilize luminescent polymers in mixed ultrathin films adsorbed in solid matrices. (C) 2011 Elsevier B.V. All rights reserved.
  • Imagem de Miniatura
    Item
    Acesso aberto (Open Access)
    Estudo de copolímeros conjugados em líquido iônico
    (Universidade Federal de São Paulo, 2018-03-27) Pesco, Beatriz [UNIFESP]; Philadelphi, Laura Oliveira Peres [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Conjugated polymers are widely studied materials due to their diversity in applications. However, its rigidity gives the material low solubility. One strategy to solve this problem is to insert flexible groups into the insoluble conjugate material. In this context, the present work presents the synthesis of a block polymer, which is composed of intercalated conjugated and non-conjugated segment, derived from poly(p-phenylene vinylene) (PPV) and poly (ethylene oxide) (PEG). The material was synthesized and characterized by infrared, UV-Vis and fluorescence and the results showed a better solubility of the block polymer in organic solvent forms without loss or alteration of its adsorption and emission good. This material was incorporated into the ionic liquid (LI) butyltrimethyl ammonium bitrifloromethanesulfonylideide in proportions of 1: 1 and 3: 1 (polymer mass ratio / LI). The results obtained with X-ray diffraction show that the block material was crystalline and when the insertion of the ionic liquid it was observed in decrease of this crystallinity. It was also observed difference in absorption, emission, DSC and TGA files, showing that there is an interaction between the block polymer material and the ionic liquid, which promoted improvement in the emission intensity and greater thermal stability.
  • Nenhuma Miniatura disponível
    Item
    Somente Metadadados
    Langmuir and Langmuir-Blodgett films of Cl-PPV mixed with stearic acid: implication of the morphology on the surface and spectroscopy properties
    (Springer, 2015-03-01) Sakai, Andrei [UNIFESP]; Peres, Laura O. [UNIFESP]; Caseli, Luciano [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    The molecular architecture of polymeric films can be changed in order to obtain enhanced properties for the fabrication of optoelectronic devices. in this paper, poly(2-chloro-p-phenylenevinylene) was spread on the air-water interface and mixed with stearic acid in order to form stable Langmuir monolayers. These films were transferred from the air-water interface to solid supports as Langmuir-Blodgett (LB) films. the influence of Cl in the polymer chain was investigated with measurements of surface pressure, polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS), Brewster angle microscopy (BAM), atomic force microscopy (AFM), and fluorescence spectroscopy. the immobilization of this polymer on solid supports as LB films provided a high control of its morphological and luminescence properties, which may be useful tomanipulate structures at the molecular level to be applied as optoelectronic devices.
  • Imagem de Miniatura
    Item
    Acesso aberto (Open Access)
    Preparação e caracterização de filmes finos de PPV contendo grupos doadores e aceptores de elétrons
    (Universidade Federal de São Paulo, 2014-11-18) Soares, Cecília Goncalves [UNIFESP]; Philadelphi, Laura Oliveira Peres [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    The present work was divided into two steps. The first one, the synthesis of precursor materials for polymerization by the Wessling route of poly(p-phenylene vinylene) (PPV) based materials containing acceptor (cyan) and donors (acetoxy) groups of electrons. The synthesis proved to be satisfactory, due to the obtainment pure products, confirmed by ¹H-NMR and ¹³C-NMR, and with high yields. The syntheses of the polymers were presented molecular weight lower than 12000 Da after process of purification. In the second step, the influence of the dicyano group in a copolymer of PPV, DCNPPV-PPV, was studied as its formation as in Langmuir and Langmuir-Blodgett (LB) film and its incorporation organophilic montmorillonite clay (OMMT). The Langmuir films were obtained from the pure copolymer and these films were compressed to a surface pressure of 45 mN/m without attaining the monolayer collapse. These films were transferred to solid substrates through the Langmuir-Blodgett (LB) technique, forming monolayers with few aggregates and low roughness. The incorporation of the copolymer in organophilic montmorillonite clay (OMMT) was efficient and the fluorescence analysis confirmed the incorporation of the copolymer in all proportions employed. The thermogravimetry analyses showed the thermal protection in the copolymer. In the sample containing 1% of the incorporated copolymer, a greater incorporated percentage was observed and at fluorescence analysis demonstrated a lower formation of excimers and aggregates, suggesting that the polymer chains are located in the lamellar space of the clay.
  • Nenhuma Miniatura disponível
    Item
    Somente Metadadados
    Ultrathin films of poly(2,5-dicyano-p-phenylene-vinylene)-co-(p-phenylene-vinylene) DCN-PPV/PPV: A Langmuir and Langmuir-Blodgett films study
    (Elsevier B.V., 2015-02-20) Soares, Cecilia Goncalves [UNIFESP]; Caseli, Luciano [UNIFESP]; Bertuzzi, Diego Luan; Santos, Fabio Santana; Garcia, Jarem Raul; Peres, Laura Oliveira [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); Universidade Estadual de Ponta Grossa (UEPG)
    Manipulation of polymeric films at the molecular level can be appropriate to improve the properties of optoelectronic devices. in this paper, the copolymer poly(2,5-dicyano-p-phenylene-vinylene)-co-(p-phenylene- vinylene) (DCN-PPV/PPV) was spread on the air-water interface forming Langmuir films. the monolayers were investigated with surface pressure-area isotherms, and polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS). the monomolecular films were then transferred to solid supports through the Langmuir-Blodgett (LB) technique, and characterized by PM-IRRAS and atomic force microscopy, with the viability of the film as an optical device investigated with fluorescence spectroscopy. the immobilization of this copolymer on solid supports as LB films provided a molecular architecture with control of their molecular properties, which may have applications for the production of optoelectronic devices. (C) 2014 Elsevier B.V. All rights reserved.