Dynamics in aqueous solutions of poly(vinyl alcohol) and its hydrophobically modified anionic analogues

The dynamics of aqueous solutions of unmodified poly(vinyl alcohol) (PVA) and of hydrophobically modified anionic analogues with two different degrees of hydrophobic substitution (HMPVA 1 and HMPVA2) is studied with the aid of viscometry and dynamic light scattering (DLS). The viscosity results reveal a pronounced polyelectrolyte effect in dilute solutions of HMPVA1, while strong association effects, even at very low concentrations, are observed in solutions of the analogue with the highest hydrophobicity. The relaxation times for solutions of PVA are practically independent of concentration over the considered range. For the hydrophobically modified analogues, both the fast and the slow relaxation times increase with increasing concentration for both systems, but the concentration dependencies of the relaxation times are much stronger for HMPVA2 due to enhanced hydrophobic associations.