Combining Hardness and Flexibility in Coatings Based on Nanoparticle-filled Hyperbranched Polymers

INTRODUCTION The combination of hardness, scratch resistance and flexibility is a highly desired feature in many coating applications. A potential route to achieve this aim is via the introduction of a nanoparticle filler into the polymer resin. The great interest for using nanoparticles to reinforce polymers emerged in the late 1980s when a research group from Toyota reported their findings regarding the possibility of building a nanostructure from a polymer and an organophilic clay, with dramatic property improvements. Since then, improvements in mechanical properties, barrier properties, solvent resistance, thermal properties and optical properties have been reported for a variety of different polymers. The employment of dendritic polymers in the preparation of nanocomposites, has been shown to promote the dispersion (exfoliation) of the nanoparticles and stabilize the exfoliated structure. Furthermore, the unique features of dendritic polymers are also very favorable in coating applications; in addition to the large number of end-groups, offering versatile cross-linking possibilities, the globular structure of dendritic polymers enables a maintained low viscosity even at high molecular weights. The aim of this study is to obtain a hard and scratch resistant coating, with maintained flexibility, through the introduction of a nanoparticle filler in a polymer resin based on the hyperbranched polyester Boltorn H30.