RESUMO
The magnetic properties of gamma-Fe2O3 nanoparticles embedded in a thermoplastic elastomer poly(ether-ester) copolymer by the in situ polycondensation reaction process have been investigated by means of magnetization and ferromagnetic resonance (FMR) measurements at low filler concentrations of 0.1 and 0.3 wt% with the magnetic additive introduced in the polymer matrix in powder and solution form. The magnetic behavior of the magnetopolymeric nanocomposites indicates significant interparticle interaction effects that depend mainly on the dispersion state of the magnetic nanoparticles as well as their concentration, consistent with the variation of the particle microstructure characterized by magnetic aggregates in the nanometer and micron scale for the solution and powder dispersions, respectively. The magnetization and FMR results at different filler concentrations and dispersions show a close correspondence to the relaxation processes of the copolymer, implying the coupling of polymeric and magnetic properties.
Assuntos
Cristalização/métodos , Compostos Férricos/química , Magnetismo , Nanoestruturas/química , Nanotecnologia/métodos , Ésteres , Substâncias Macromoleculares/química , Teste de Materiais , Conformação Molecular , Nanoestruturas/ultraestrutura , Tamanho da Partícula , Propriedades de SuperfícieRESUMO
The aim of this study was to investigate the effect of carazolol on the generation of the oxygen species with respect to chemiluminescence (CL) from the copper ion/H2O2 system. The reactions are carried out in buffered aqueous solution. The quantum yield of the CL from the copper ion/H2O2 system is increased by a factor of 2(-10) in the presence of carazolol. The CL spectra from the carazolol/copper ion/H2O2 system are spread through the full visible region and four emission bands are shown at maxima 480-500, 580, 640 and 700 nm. The excitation spectrum obtained from the above mentioned system shows the main maxima at around 273, 310 and 340 nm (lambda obs = 365 nm). The fluorescence emission spectrum exhibits only one maximum at 365 nm (lambda exc = 340 nm) corresponding to carazolol. The light emission decreases in the presence of several biologically important compounds which are typical scavengers of oxygen radicals and singlet oxygen (1O2). The results demonstrate that carazolol enhances the production of oxygen radicals and 1O2 under our experimental conditions. Generation of 1O2 was additionally confirmed using ESR spin trapping and spectrophotometry.
