Modification of polyurethane by the lateral cross-linking using a modified poly(vinyl alcohol) for the improvement of tensile strength and the control of water vapor permeation

The hydroxyl groups of poly(vinyl alcohol) (PVA) was capped with phenylisocyanate, ethylisocyanate, or octylisocyanate to reduce the hydrophilicity and to improve the compatibility with organic solvent. The modified PVA was used to laterally cross-link the polyurethane (PU), and a Control PU series containing free modified PVA was also prepared for comparison. The PVA cross-linking significantly improved the tensile strength, whereas the Control series did not. The thermal properties ( T g , T m , and Δ H m ) did not change with the incorporation of PVA cross-linking. The breaking strain of the PU series was not affected by the PVA cross-linking. The shape recovery and shape retention of the PU series remained high with the increase of PVA content. The low-temperature flexibilities of PU series was not changed by the PVA cross-linking, whereas the water vapor permeability was reduced by the PVA cross-linking.