Waterborne polyurethane (WPU) has been widely used in various applications, such as adhesive or coating in printing and packaging, due to its versatile performance and environmental benefits. However, it still poses a challenge when it comes to additive manufacturing of three-dimensional structures because of its low viscosity and poor dispersibility. In this work, cellulose nanofibrils (CNF) were added into the in-situ synthesis method of WPU during the emulsification process to reduce the nanoparticle size and to increase the viscosity. As a rheological modifier, additional CNFs were added to further improve printability. WPUCNF/CNF inks demonstrated superb printability in the form of honeycomb, woodpiles, or human ear shapes after the proper dewatering process. The concentration for previously reported 3D printing WPU ink was around 20-30%, while for this work the concentration of ink can be controlled as low as 2.8–7.4%. With the adding of hygroscopic salt CaCl2, 17-37% of water can be absorbed while the pressure resistance can be improved to withstand more than 20 compression cycles. This flexible and eco-friendly WPUCNF/CNF ink can show a broader vision in different applications in the field of biomaterials.

Cellulose nanofibrils aided waterborne polyurethane synthesis and its application for 3D printing

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.