Poly(N-vinyl-2-pyrrolidone)-Monoalkyl Xanthates. 1. Adsorption and Chemical Reaction

The interaction of poly(N-vinyl-2-pyrrolidone) (PVP) with potassium monoalkyl xanthates was studied by UV-vis spectrophotometry and ultrafiltration measurements. A simple association model was applied in order to describe the results. Some characteristics of the association process were analyzed. The findings suggest the presence of a more complex process than one simple association or chemical reaction process. We have supposed that the absorption obtained corresponds to the adsorption of the product. From the second-order rate constant values of the chemical reaction, we have calculated the activation free energy ΔG* for the reaction of each xanthate studied with PVP and its variation with the number of carbon atoms in the alkyl chain. The different contributions to ΔG* values are discussed in terms of the one specific ionic interaction between -OCSS- and one positive active center in the polymer chain and one hydrophobic association with the backbone of the PVP.