Syntheses and spectroscopic pH titrations of naphthol-labeled poly(methacrylic acid)s

Poly(methacrylic acid) (PMA) and poly(acrylamide) (PAAm) with a small mole fraction of naphthol (NpOH) residues were prepared by polymerization of methacrylic acid or acrylamide with three position isomers, methacryloylaminonaphthol. The substiluent effect on the apparent pK values (pK(obsd)) determined by spectroscopic pH titrations in aqueous solution, was observed for the NpOH-Iabeled PAAm. The electrostatic surface potential (psi) for PMA was calculated From the difference in the pK(obsd) values for the labeled PMA and PAAm. The obtained psi value decreased as the spacing between the OH moiety and the polymer main chain increased. This clearly indicates that the psi value is a sensitive function of the distance from the polyion surface.