Photophysical study of the interactions of charged copolymers with surfactants of opposite charge

The interactions between PSS-nBVE copolymers and oppositely charged ionic s urfactants (CTAC) in aqueous solution have been investigated using pyrene a s a photophysical probe. Static and dynamic fluorescence determinations hav e been used to obtain information about the microenvironments formed. Micro polarity studies using the I-1/I-3 ratio of the vibronic bands of pyrene sh ow the formation of hydrophobic domains. Early formed premicelles due to th e electrostatic interactions between the copolymers and the surfactant (hav ing I-1/I-3 ratios around 1.5-1.6) attract initially the free probes that w ill migrate from the more aqueous environment to these new hydrophobic site s. The cac's at which these premicelles are formed are found at 0.27 +/- 0. 2 mM. Pyrene excimers are detected in the same concentration range. At high er surfactant concentrations free micelles are formed with the same propert ies of micelles in solutions without polymers, presenting I-1/I-3 ratios ar ound 1.3 and cmc's around 1.45 mM. Also new excimers are formed that disapp eared during the progressive addition of the surfactant.