Supramolecular association induced by Fe(III) in low molecular weight sodium polyacrylate

A supramolecular association between the sodium salt of a low molecular weight polyacrylic acid (PAA, Mw = 1200) and Fe(III) is described and characterized using ultrafiltration (UF), gel permeation chromatography (GPC), dynamic light scattering (DLS), and infrared spectrometry (FTIR). The GPC and DLS experiments indicate the presence of massive and polydisperse aggregates of PAA linked by Fe(III) of ca. 100 nm in size. FTIR analysis of the symmetric and asymmetric carboxylate stretches for the polyacrylate and the different fractions indicate the bridging effect of the metal in the formation of the clusters, which incorporate practically all the iron present in solution.