High‐molecular‐weight hydrolyzed polyacrylamides. II. Potentiometric titrations

Abstract

Potentiometric titrations in water of high‐molecular‐weight partly hydrolyzed polyacrylamides were analyzed by the Lifson—Katchalsky rodlike model. A fair concordance was found between theory and experimental curves with pK0 of acid functions of about 4.75 when 0 < τ < 0.49. Two methods were derived to calculate the parameter n of the extended Henderson‐Hasselbach equation by using a series expansion of pKa vs. α, not yet reported in the literature. A new equation for n was established and comparison between two sets of values of n, obtained by using the theoretical ΔpK curves and series expansion is discussed.

Counterions Contributions in Polyelectrolyte Adsorption

“…It can be evaluated by several calculation models, but we estimate with reasonable accuracy that it is equal to pK a at a = 0 [23]. Thus, for our system, pKint is about 4,6 which agrees with values in the literature [2] and [3].…”

Measurement of Donnan potentials in gels by in situ microelectrode voltammetry

“…The two curves form an envelope of feasible Donnan potential values with the uppermost curve representing a carboxylic dissociation constant (pK a ) of 4.6 and the lower, 4.3. These values represent the upper and lower limits for dissociation constants found in the literature [54,56] for acrylamide gels. The trend of the Donnan potentials as described by the envelope provides a reasonable fit to the experimentally obtained data depicted in Fig.…”

Water‐soluble copolymers. XIII. Copolymers of acrylamide with sodium‐3‐acrylamido‐3‐methylbutanoate: Solution properties

“…This behavior is expected for two reasons. 22 First, the increased electrostatic repulsion with increasing NaAMB content causes decreased stability of the ionic groups, thereby raising the pKa. Secondly, the less NaAMB present, the more the acrylamide units are available for hydrogen bonding which will further stabilize the anion and lower the pKa.…”