Fluorescence probe study of the interaction between acrylic acid-co-ethyl methacrylate copolymers and sodium dodecylsulfate

The interaction between sodium dodecylsulfate (SDS) and acrylic acid (AA)-e thyl methacrylate (EMA) copolymers has been investigated using steady state fluorescence and conductimetric measurements to assess the effect of the p olymer composition on the aggregation process. Micropolarity studies using the ratio between the emission intensities of the vibronic bands of pyrene (I-1/I-3) and the shift of the fluorescence emission of pyrene-3-carboxalde hyde show, that the interaction of SDS with AA-EMA copolymers occurs at sur factant concentrations smaller than that observed for the pure surfactant i n water and depends on the copolymer composition. The increase of ethyl met hacrylate in the copolymers lowers the critical aggregation concentration ( CAC) due to the larger hydrophobic character of the polymer backbone. The f ormation of aggregates on the macromolecule is induced mainly, by hydrophob ic interactions, but the process is also influenced by the ionic strength d ue to the counter-ions of the polyelectrolyte.