Hybrid nanocomposites containing carboxymethylcellulose and silver nanoparticles

Silver nanoparticles have high temperature stability and low volatility, and at the nanoscale are known to be an effective antifungal and antimicrobial agent. The present investigation involves the synthesis of silver nanoparticle/carboxymethylcellulose nanocomposites. The nanoparticles synthesised in this study had sizes in the range of 100 and 40 nm. The nanocomposites formed by a combination of metallic nanoparticles and carboxymethylcellulose were characterised by contact angle measurements, solubility tests, thermal and mechanical analyses, and morphological images. Improvements in the hydrophobic properties were observed with inclusion of the nanoparticles in the nanocomposites, with the best results occurring after the addition of 40 nm nanoparticles in a carboxymethylcellulose matrix. The silver nanoparticles tend to occupy the empty spaces in the pores of the carboxymethylcellulose matrix, inducing the collapse of these pores and thereby improving the tensile and barrier properties of the film. Copyright © 2013 American Scientific Publishers All rights reserved.

Carbon nanotube-reinforced siloxane-PMMA hybrid coatings with high corrosion resistance

Siloxane-polymethyl methacrylate hybrid films containing functionalized multiwall carbon nanotubes (CNTs) were deposited by dip-coating on carbon steel substrates from a sol prepared by radical polymerization of methyl methacrylate and 3-methacryloxy propyl-trimethoxysilane, followed by hydrolytic co-polycondensation of tetraethoxysilane. The correlation between the structural properties and corrosion protection efficiency was studied as a function of the molar ratio of nanotubes carbon to silicon, varied in the range between 0.1% and 5%. 29Si nuclear magnetic resonance and thermogravimetric measurements have shown that hybrids containing carbon nanotubes have a similar degree of polycondensation and thermal stability as the undoped matrix and exhibit and excellent adhesion to the substrate. Microscopy and X-ray photoelectron spectroscopy results revealed a very good dispersion of carbon nanotubes in the hybrid matrix and the presence of carboxylic groups allowing covalent bonding with the end-siloxane nodes. Potentiodynamic polarization curves and electrochemical impedance spectroscopy results demonstrate that CNTs containing coatings maintain the excellent corrosion protection efficiency of the hybrids, showing even a superior performance in acidic solution. The nanocomposite structure acts as efficient corrosion barrier, increasing the total impedance by 4 orders of magnitude and reducing the current densities by more than 3 orders of magnitude, compared to the bare steel electrode. © 2013 Elsevier B.V. All rights reserved.

Luminescent properties of hybrid materials prepared by the polymeric precursor method

Rare earth complexes (RE) can be incorporated in silica matrixes, originating organic/inorganic hybrid materials with good thermal stability and high rare earth emission lines. In this work, the hybrid material was obtained by the polymeric precursor method and ultrasonic dispersed with spherical silica particles prepared by the Stöber Method. The Raman spectra indicated that the Eu3+ ions are involved in a polymeric structure formed as consequence of the chelation and polyesterification reactions of this ion with citric acid and ethylene glycol. After the ultrasonic stirring, 2-hydroxynicotinic ligand will also compose this polymeric rigid structure. The TGA/DTA analysis showed that this polymeric material was thermal decomposed at 300 °C. Moreover, this process allows the chelating process of the 2-hydroxynicotinic acid ligand to the Eu3+ ions. The 29Si NMR showed that the ultrasonic dispersion of the reactants was not able to promote the functionalization of the silica particles with the 2-hydroxynicotinic acid ligand. Moreover, heat treatment promotes the [Eu(HnicO2)3] complex particles incorporation into silica pores. At this temperature, the TGA curve showed that only the thermal degradation of ethylene glycol and citric acid used during the experimental procedure occurs. The silica and hybrid materials are composed by spherical and aggregated particles with particle size of approximately 450 nm, which can be influenced by the heat treatment. These materials also present an absorption band located at 337 nm. The photoluminescent study showed that when the hybrid samples were excited at 337 nm wavelength, the ligand absorbs the excitation light. Part of this energy is transferred to the Eu3+ ion, which main emission, 5D0→ 7F2, is observed in the emission spectrum at 612 nm. As the heating temperature increases to 300 C, the energy transfer is more favorable. The lifetime values showed that the Eu3+ emission is enhanced due to the energy transfer process in the powders. © 2013 Elsevier B.V. All rights reserved.

Estudo das propriedades físicas de blendas de PVDF/Látex visando aplicação como biomaterial

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Otimização das condições de síntese de amostras cerâmicas do composto Y'Ba IND. 2''Cu IND. 3''O IND. 7'-δ através do Método Pechini

Pós-graduação em Ciência e Tecnologia de Materiais - FC

Formadores de filmes híbridos orgânicos inorgânicos do tipo ureasil-poliéter para liberação controlada de fármacos

Pós-graduação em Ciências Farmacêuticas - FCFAR

Matrizes poliméricas reticuladas de alta amilose e pectina para liberação controlada de fármacos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Propriedades de materiais nanoestruturados do sistema epoxídico DGEBA/TETA modificado com um éster de silsesquioxano

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Preparação de espuma cerâmica à base de zircônia pelo processo sol-emulsão-gel

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Síntese, caracterização e propriedades da matriz sílica-carbono impregnada com níquel obtida pelo método dos precursores poliméricos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo da cinética de cura e das propriedades térmicas da resina benzoxazina e de seus compósitos nanoestruturados

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação dos parâmetros de processo de reticulação do polietileno de baixa densidade

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Fabricação e caracterização de filmes finos de perileno: arquitetura molecular e aplicações sensoriais

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Caracterização dos constituintes do látex e da borracha natural que estimulam a angiogênese

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Caracterização tecnológica das argilas da cidade de Cunha para fins de cerâmica artística

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)