Studies of polymer solvation by dielectric relaxation spectroscopy. Part 6.—Poly(acrylic acid) in some polar solvents

Abstract

The dielectric spectrum of solutions of poly(acrylic acid)(PAA) is measured over a broad frequency range (a few MHz to 72 GHz) using the following solvents: dimethyl sulfoxide, tetramethylurea, methylpyrrolidone (NMP) and water. Polymer concentrations are up to a mole fraction of monomeric repeat units of 0.14 (PAA 250 000 with the non-aqueous solvents) or 0.35 (PAA 4000 in aqueous solution), at temperatures of 20 °C and also 40 and 60 °C for NMP and water. Results are discussed particularly with respect to the solvent behaviour which can be assigned to (i) unaffected (bulk-type), (ii) loosely affected and (iii) quasi-bound solvent. The latter contribution is more pronounced than with comparable polymers. This, as well as some other features, is likely to be due to the hydrogen-bonding ability of PAA.