Physically interpenetrating networks in polyurethane ionomers/poly(vinyl alcohol) blends

Three series of blends of polyurethane ionomers (PUI) with poly(vinyl alcohol) (PVA) were prepared by mixing aqueous PUI emulsions with aqueous PVA solutions and then allowing them to dry. The characterization of the blends of various compositions was carried out using infrared spectroscopy, dynamic mechanical analysis, differential scanning calorimetry and tensile-elongation testing. It was found that poly(ether-urethane) cationomer (Cat-Et)/PVA-1 and poly(ether-urethane) anionomer (An-Et)/PVA-2 blends exhibit a positive synergistic effect with respect to the tensile strength and that the amorphous phase of PVA is at least partially compatible with both the disordered hard domains and the soft domains of the ionomers. For the former blends, this behaviour is due to the formation of hydrogen bonding with the glycolate anions and ether groups, and for the latter blends to the formation of hydrogen bonds with the ether groups. For poly(ester-urethane) cationomer (Cat-Es)/PVA-3 blends, there is no hydrogen bonding between these two components and no synergistic effect in the tensile strength after blending. Physically interpenetrating polymer networks (IPNs) are expected to occur in the former two blends, but not in the latter one.