Enhance effect of surfactants on the photoluminescence and photostability of water-soluble poly(phenylene ethynylene)

The interaction between the water-soluble anionic fluorescence conjugated polyelectrolytes PPESO 3 (poly2,5-bis(3-sulfonatopropoxy)-1,4-phenylethynylene-alt- 1,4-poly(phenylene ethynylene)]) and various surfactants has been studied in aqueous solution by UV-vis absorption spectra and fluorescence spectra. With the addition of surfactants, the aggregations of polymers are broken up. For eliminating the self-quenching effect of the fluorescent polymers, the photoluminescence of PPESO 3 is dramatically enhanced. The photoluminescence of PPESO 3 can be enhanced 6- to 12-fold with the addition of different surfactants, and at higher concentration of surfactants, the photostability of PPESO 3 is also highly increased. A "micelle incorporation model" is proposed to explain the enhancement of photostability. To deeply understand the interaction processes between PPESO 3 and surfactants, we systematically studied the fluorescence spectra changes of PPESO 3 and the dynamic processes at different CTAB concentrations. All results prove the surfactants can simultaneously enhance the photoluminescence and photostability of water-soluble conjugated polyelectrolytes, and this method is very simple and powerful.