Sorption of sodium dodecyl sulfate by polyaniline–cellulose acetate polymeric blends as seen by UV–vis spectroscopy

The interaction between sodium dodecyl sulfate (SDS) and a blend of polyaniline (PANi) and cellulose acetate (CA) is discussed. This interaction is shown to lead to a red shift of the maximum absorption wavelength in the visible spectrum. The behaviour, which is similar to what is seen on protonation of PANi at pH ≤ 3, may be due to alteration in the lamellar structure of the polymer upon SDS sorption. The interactions between SDS and the blend film show multi-equilibrium-type sorption, which are dependent on the PANi content. This process is accompanied by chemisorption as well as by alteration of the structure of the polymer matrix, as confirmed by scanning electron microscopy (SEM). The kinetics of sorption of SDS by polymer blend films is dependent both on the PANi content in the blend and the surfactant critical micelle concentration (cmc). The two blends studied show a high sensitivity to SDS, which make them promising matrices as surfactant sensors.