Aplicação da microscopia otica de fluorescencia ao estudo de polimeros e blendas polimericas de PVA/PVAc

AUTOR(ES)
DATA DE PUBLICAÇÃO

1994

RESUMO

A morphological study of polymer blends of 87-89% hydrolized PVA (124.000-186.000) and PVAc (high molecular weight) has been made using the relative compositions 9:1, 1:1 and 1:9, containing fluorescein (0,1% m/m). The formation of two phases, from a process of liquid-solid phase separation has been observed during the solvent(ethanol/water) evaporation The analysis of the polymer blends containing fluorescein, using fluorescence optical microscopy, demonstrated that the two phases have non-fluorescent (richer in acetate groups) and fluorescent domains (richer in hydroxyl groups). It was concluded that a discrimination of the composition of domains through fluorescence optical microscopy can be carried out. Mapping of richer regions in acetate groups, specifically for these blends, however, can only be made through the lack of fluorescein emission. In order to improve the discrimination of the different domains, blends of PVA/ PVAc have been prepared using the compositions above and containing: (a) only anthracene, (b) both, the anthracene and fluorescein (0,1% m/m). Anthracene is non polar and it presents a high quantum yield of fluorescence emission. This dye may be dissolved, preferentially, in non polar polymeric matrices. The analysis of the fluorescence optical photomicroscopy of blends containing the two dyes has revealed that PVAc-richer regions are fluorescent in the blue region (anthracene emission) and the PVA-richer regions are fluorescent in the green region (fluorescein emission). Nevertheless, it has been observed that anthracene has modified the morphology of the studied polymer blends due to its polarity, while fluorescein has not. Electronic absorption and fluorescence emission spectroscopy and infrared spectroscopy have algo been used complementary. Conclusions obtained by these techniques on the qualitative composition of each phase confirm the above-mentioned.

ASSUNTO(S)

microscopia de fluorescencia microscopia otica polimeros

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