Abstract
The interaction between an anionic dye methyl orange and three poly cations namely, poly (N-methy-4-vinylpyridinium iodide) (PM4VPI), poly (vinylbenzyltriphenyl phosphonium chloride) (PVBTPPC) and poly (N-methy-4-vinylpyridinium iodide) (PM2VPI) has been investigated by spectrophotometric method. The polymers were observed to induce metachromasy in the dye as evidenced from the considerable blue shift in the absorption maxima of the dye. The interaction constant and thermodynamic parameters of interaction have been determined by absorbance measurements at the metachromatic band. The effect of additives such as ionic salts, alcohols, urea and polyelectrolytes on the reversal of metachromasy has been studied and used to determine the stability of the metachromatic complex and to understand the nature of binding.