Degradação de poliestirenossulfonato de sódio fotossensibilizada pelo corante QTX / Degradation of poly(styrenesulfonate) photosensitised by QTX dye

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

The poly(styrenesulfonate) (PSS) photosensitised by 2-hydroxy-3-(3,4-dimethyl-9-oxo-9H-thioxanthen-2-yloxy)-N,N,N-trimethyl-1-propanium chloride (QTX) solution degradation mechanism was investigated. Initially, the photodegradation of QTX in aqueous solution was studied. The photoproducts generated photolysis were characterized as being sulfones and sulfoxides, which were identified by HPLC-MS. The photodegradation of QTX in aqueous solution was also followed by UV-Vis absorption spectra, suggesting the formation of sulfoxides. The elementary reactions of QTX in aqueous solution were investigated by laser flash photolysis. The quenching rate constant values of the triplet state QTX in the presence of potassium sorbate and hydroquinone were close to the value of diffusion constant. It was possible to propose the mechanism of QTX degradation combining the results from the different techniques. The photodegradation PSS in aqueous solution in the presence and absence of QTX was monitored by size exclusion chromatography and viscosity. The photodegradation of PSS was observed only in the presence of QTX. In this condition a decrease of Mw was observed, which means the random chain scission. The PSS/QTX degradation was also investigated in the presence of potassium sorbate, a triplet quencher. In this case, an increase of degradation percentage occurred. These results suggested that the degradation mechanism of PSS degradation photosensitised by QTX occurs mainly by the singlet excited QTX abstracts a hydrogen from the polymer and in the presence of oxygen leads to radicals formation which contributed to the degradation process.

ASSUNTO(S)

photosensitiser fotodegradação qtx poliestirenossulfonato de sódio qtx poly(styrenesulfonate) fotossensibilizador photodegradation

ACESSO AO ARTIGO

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