Polymer-polymer complexation in dilute aqueous solutions. Poly(acrylic acid)-poly(ethylene oxide) and poly(acrylic acid)-poly(vinylpyrrolidone)

Fluorescence spectroscopy of pyrene-labeled poly(acrylic acid) (PAA) was used to study its interactions with poly(ethylene oxide) (PEO) and poly(vinylpyrrolidone) (PVP) in aqueous solutions. The effects of molar ratio, molecular weight, and solvent were also investigated. Hydrogen bonding is the primary mechanism of interaction among these polymers. Excimer fluorescence studies show that the PVP-PAA complex is stronger than and exists in a more constricted form than the PEO-PAA complex. Interactions between PVP and PAA are prevalent over a wider pH range than those of PAA and PEO. The higher electronegativity of the oxygen in the pyrrolidone group is attributed as the reason for the stronger interaction of PVP with poly(acrylic acid).