Enhanced thermal and surface properties of waterborne UV-curable polycarbonate-based polyurethane (meth)acrylate dispersion by incorporation of polydimethylsiloxane

Hydroxy-terminated polydimethylsiloxane (PDMS) was incorporated into the soft segments of UV-curable polycarbonate-based polyurethane (meth)acrylate dispersions to improve the thermal property and surface property. 2-Hydroxymethacylate or pentaerythritol tri-acrylate was end-capped with or without PDMS to confirm the effect of the functionality of the end-capping group on the properties. Owing to the hydrophobicity of siloxane, the cured coating films containing PDMS had low surface free energy, and higher thermal degradation temperature. The functionality of the end-capping group had a slight effect on the surface and thermal properties. The UV-curing rate and final conversion depended strongly on the functionality. The glass transition temperature and the tensile strength of the cured films were increased by incorporating PDMS or increasing the functionality. Therefore, the weaknesses of waterborne UV-curable coatings can be alleviated by the incorporation of PDMS and high functionality. (C) 2011 Elsevier Ltd. All rights reserved.