Phase relations in ammonium heptamolybdate-poly(vinyl alcohol)-water mixtures

Phase relations in ammonium molybdate tetrahydrate-poly(vinyl alcohol)-wate r mixtures were studied. An isothermal section of the phase diagram for roo m temperature was obtained. Phase relations for polymer-salt compositions e xposed to light or stored in dark are significantly different. In light, ho mogeneous aqueous solutions of salt and polymer exist over a fairly wide re gion, forming molecular complexes with partially reduced molybdenum. In pol ymer-rich compositions, solid solutions in it exist whose concentration ext ent is wider as the water content increases. Several heterogeneous fields e xist in the system where two or three phases coexist: a liquid polymer-salt solution, a solid polymer-salt phase, and ammonium heptamolybdate crystals . A reduction in the water content gives rise to phase inversion in the het erogeneous region: the system changes its state from a liquid dispersion me dium to a solid dispersion medium in which liquid drops are contained. Data are obtained allowing the inference to be made that mesomorphic entities, like liquid-crystalline ones, can exist in the system in question, which is related to a novel phenomenon: the induced stiffness of macromolecules of flexible-chain water-soluble polymer due to complexing with inorganic polya nions.