Design and development of 4D-printed cellulose nanofibers reinforced shape memory polymer composites: Application for self-deforming plant bionic soft grippers

Shape memory polymers (SMPs) have facilitated the development of smart materials. The SMPs can be used in 3D printing technology to achieve intelligent deformation over time, i.e., 4D printing. This study used a simple preparation method to develop polycaprolactone (PCL)/poly butyleneadipate-co-terephthalate (PBAT) thermally responsive shape memory polymer composites reinforced by cellulose nanofibers (CNFs). Adding CNFs at 1 part per hundred (1 phr) of polymer mass enhanced the mechanical performance and composites' interfacial bonding. In addition, the polymer composites demonstrated good 3D printability. 4D printed thermal response self-deforming structures were designed using the shape memory effect, climbing plant bionic model, and 3D printing technology. This study demonstrated the fast response and stable winding of 4D printed self-deforming structures for soft grippers. The advanced 4D printed soft grippers with thermally induced deformation and bionic approach are anticipated to assist the development of biomedical devices, soft robotics, smart actuators, and other areas.