Neutralization Degree Effect on Potentiometric Behavior of Poly(N-octyl-4-vinylpyridinium Bromide)

In this work, we synthesized poly(4-vinylpyridine) (P4VP) using radical polymerization. A pair of copolymers containing the poly(4-vinylpyridine) were quaternized using octyl bromide to get the P4VP-C8Br with the degrees of quaternization of 48.8% and 72%. The P4VP and these two copolymers were characterized by H-1 NMR, IR, and ATG. Moreover, we studied the impact of the extent of quaternization and the concentration on the interaction of the P4VP-C8Br 48.8% and P4VP-C8Br 72% copolymers with proton H+ at 25 degrees C within the neutralization range of (0-1). In addition, potentiometry technique was performed to evaluate the interactions at different concentrations, and a phase diagrams of solubility was established in the concentration interval of (0.6 x 10(-4) g l(-1)-3 x 10(-4) g l(-1)) for the two copolymers. The variation of pKa versus the concentration of copolymer and its quaternization rate was examined. In the neutralization degree range of (0 < a < 1), the copolymer caused a modification in the structure and conformation due to the presence of hydrophobichydrophilic and hydrophobic-hydrophobic interactions.