Recent developments in waterborne polyurethanes for coating applications

Abstract

In recent years, the need to use more environmentally friendly polymers has emphasized research for the development of polymers in dispersions in water. In an effort to meet this goal, water-based polyurethanes (WBPUs) were developed, which release almost benign water vapour to the atmosphere during use as supported or self-standing films for different applications instead of huge amounts of volatile organic compounds (VOCs), as is the case with most traditional solvent-based polymers. One of the most studied applications for this type of materials are water-based paints for coatings applications. In this chapter, we will analyse the latest advances regarding the development of WBPU from multiple hydroxyl group (OH) sources, as well as the different types of chain extenders and emulsifiers used in their preparation. On the other hand, to improve performance according to the aimed (required) or final application, mechanical properties (tensile strength, elasticitry, hardness), water resistance, thermostability, adhesion or anti-adhesion on substrate, antibacterial adhesion (antifouling) and hydrophobic property, composite formulations are tailored through the addition of organic or inorganic particles/nanoparticles. In this chapter we will briefly review neat and composite WBPUs that have been developed as specific coatings for different substrates.