STUDY OF THE POLY(N-VINYL-2-PYRROLIDONE)-NA2MOO4 INTERACTIONS IN AQUEOUS-SOLUTION - EFFECT ON THE POLYMER MORPHOLOGY

In this paper, the morphology of poly(N-vinyl-2-pyrrolidone) (PVP) in the presence of Na2MoO4 has been studied using scanning electron micro scopy (SEM). Moreover the poly(N-vinyl-2-pyrrolidone) (PVP)(2)/water(1 )/Na2MoO4(3) ternary system has been characterized by viscometry and d ensimetry. A lattice-like tridimensional structure of PVP due to its i nteraction with Na2MoO4 is observed. In this ternary system both a pre ferential adsorption of water at all solvent compositions studied is o bserved, except at 100 mM of Na2MoO4, concentration at which a prefere ntial adsorption of salt is exhibited. Na2MoO4 behaves as a salting-in agent for the macromolecule, the binary solvent mixture being thermod ynamically unfavourable at salt concentrations larger than 10 mM Na2Mo O4. (C) 1997 Elsevier Science Ltd.