Waterborne UV-curable polycarbonate polyurethane nanocomposites based on polydimethylsiloxane and colloidal silica with enhanced mechanical and surface properties

Waterborne UV-curable polycarbonate polyurethane (PCD-WUPU) nanocomposites based on polydimethylsiloxane (PDMS) and aqueous colloidal silica were prepared via an inverse emulsification process. The effects of PDMS and silica on colloidal dispersions as well as the morphology and properties of the nanostructured films were investigated. It was found that the homogeneous dispersion and network structure of silica clusters in the PCD-PDMS-WUPU matrix resulted in a significantly enhanced modulus, tensile strength, elongation at break (toughness), and thermal stability of the nanocomposite films. It was also very interesting to find that the incorporation of silica did not decrease or increase surface hydrophobicity and water resistance of the PCD-PDMS-WUPU films because of the microphase separation surface structure of the PDMS chain. The high mechanical and surface hydrophobic properties will significantly broaden the industrial applications of WUPU, especially for water-based UV-curable coatings with abrasion or scratching resistance and water resistance.