Influência da radiação gama em filmes de PPV e PTHT: caracterização óptica e elétrica

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

In this work, we investigated the effects of Gamma ionizing radiation on optical properties of the polyeletrolite poly (chloride Tetrahydrothiophen of xililideno) (PTHT) and the conjugated polymer poly(p- phenylene vinileno) (PPV). The PPV films were processed from PTHT films and it was submitted on the annealing step at low (110oC) and higher (200oC) under vacuum (0.1 atm) during 2 h. The layer-by-layer (LbL) PPV films were obtained from PTHT and the acid of the sodium dodecylbenzenesulfonate (DBS). The conventional PPV films produced via casting technique were carrier out in comparison. The LbL and casting PPV films were deposited on FTO (Fluorine Tin oxide) and quartz substrates. Effects of interface film/substrate, thickness, processing technique and conversion temperature were investigated via optical absorbance and photoluminescence. Due to the thermal instability of PTHT polymer, the effects of the radiation on this polymer was not possible to available. By using a 60Co source of gamma radiation, the samples were irradiated at dose 2Gy, compatible personal dosimeters, and at dose 100 Gy, compatible with applications in medicine, among others. The results showed, in general, that the absorbance experiment is not appropriated to analyze the radiation effects on polymer structure in this range of dose and in thin films. On the other hand, analyzing the emission properties, i. e., PL intensity (IPL), quantum emission efficiency (h) and the coupling electron-phonon (S), the effects at lower dose is detectable. The best result was obtained for LbL PPV/DBS films with 20 bilayers on FTO substrate and thermal converted at 200oC. In addition, for this film deposited on FTO substrate (fingers electrodes), a significant increase (4 orders) in the conductivity after the radiation at 100 Gy was obtained. Finally, the new methodology for analyses of the effects of radiation on conjugated polymers opens the possibility to use this material as ionizing radiation sensor.

ASSUNTO(S)

poli (p-fenileno vinileno) polímeros interaction radiationpolymer sensor raios gama radiação gama fisica gamma ionizing radiation

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