The hydrogen-bonding interpolymer association between poly(acrylic acid) (PAA) and the poly( N, N -dimethylacrylamide) (PDMAM) side chains of a negatively charged graft copolymer was studied in aqueous solutions. The graft copolymers, P(AA- co -AMPSA)- g -PDMAM, contain 50 wt % PDMAM, while their backbone comprises acrylic acid (AA) and mostly 2-acrylamido-2-methylpropane sulfonic acid (AMPSA) units. The formation, at low pH, of compact and soluble hydrogen-bonding interpolymer complexes between PAA and the side PDMAM chains, is suggested by combining turbidimetry and dilute solution viscosity measurements. Moreover, in semidilute solutions, the pH-controlled association−dissociation of these water-soluble hydrogen-bonding interpolymer complexes results in a spectacular pH-controlled thickening behavior.
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Sotiropoulou et al. (2003) studied this question.
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