Potentiometric Titrations of a Polyelectrolyte

Abstract

A study was carried out on the potentiometric titrations of poly(vinyl alcohol) partially acetalized with glyoxylic acid (PVAG). The titration curves were known to fulfil the relation proposed already by Pals and Hermans and the dissociation exponents were determined thereby. The radius of this polyacid was estimated from the electro-static free energy change by means of our theoretical treatment of polyelectrolyte solutions : it was found that the size decreased with the concentration, consistently with the well-known variation of the viscosity. Moreover, a potential potentiometrically obtained was shown not to be in agreement with the surface potential electrophoretically determined. This could be understood by referring the former to an average potential inside the spherical macro-ion.