Waterborne polyurethane-urea dispersion with chain extension step in homogeneous medium reinforced with cellulose nanocrystals

Waterborne polyurethane-urea (WBPUU) dispersions have gained attention towards environmentally-friendly synthesis routes. Differing from the conventional WBPUU synthesis route where the diamine chain extension is performed in heterogeneous medium in the surface of the already formed particles, in this case the chain extension was carried out in homogeneous medium, prior to WBPUU nanoparticles formation. Thus, stable WBPUU dispersion with small particle sizes and narrow distribution was synthesized. Furthermore, cellulose nanocrystals (CNC) were isolated for the preparation of eco-friendly nanocomposites just by mixing. Nanocomposites with different CNC contents were prepared and extensively characterized in terms of physicochemical, thermal, thermomechanical and mechanical properties, hydrophilic behavior and morphology.