The environmental awareness has increased the research and development of eco-friendly green
synthesis routes for many different applications, such as the waterborne polymer systems. Among
others, waterborne polyurethanes (WBPU) and waterborne polyurethane-ureas (WBPUU) have gained
attention due to their versatility in terms of composition and properties, making them suitable in a
wide range of applications [1]. WBPU and WBPUU synthesis process is based on the incorporation of
internal emulsifiers covalently bonded to the polymer obtaining stable water dispersions over months.
Furthermore, the waterborne character of the dispersions provides the opportunity of incorporating
water dispersible nanoentities and water soluble additives, enhancing or even providing additional
properties. In this context, the use of renewable derivatives opens the possibility of enhancing the
environmentally-friendly character. Among them, cellulose nanocrystals (CNC) are presented as a
suitable candidate for the preparation of nanocomposites, considering their unique properties in the
nanoscale dimension, provided by their high length/diameter aspect ratio and high specific mechanical
properties [2]. Otherwise, the incorporation of natural water soluble additives has focused attention on
extracts obtained from plants, consisting in biologically active compounds [3], whose antimicrobial
character can determine the antimicrobial behavior of the WBPU and WBPUU. Therefore, in this
work, different strategies have been analyzed for the preparation of WBPU-CNC nanocomposites and
WBPUU-plant extracts varying their content as well as their incorporation route.info:eu-repo/semantics/publishedVersio
