Shape-memory polymers (SMPs) are a class of materials that respond to external stimuli with the ability to alter a pre-programmed shape to its original shape. SMPs have acquired a broad interest in the material field due to their versatile biomedical, structural, and soft robotics applications. Here we present a 3D printing mechanism using an in-house multiphase direct ink writing (MDIW) process with composite printing capability to produce shape-morphing structures using polymers and nanoparticles. The fabricated structure showed thermal and magnetic dual stimuli responsiveness allowing it to actuate or recovery from any complex shapes. The shape memory composites were based on polyether- and polyester-thermoplastic polyurethane’s (TPU). In addition, polycaprolactone (PCL) and iron oxide (Fe<sub>3</sub>O<sub>4</sub>) nanoparticles were incorporated to enhance thermal and magnetic actuation behaviors. The fabricated shape-memory structures had a wide range thermal actuation temperature (40 – 65 °C), high strain recovery, and high responsiveness due to intermittent short- and long-range molecular order. Parametric studies with different shapes, thicknesses, and actuation mediums (e.g., water, air, and alcohol) were conducted to understand the actuation mechanism. The study also demonstrated the one-step composite printing mechanism, which has not been performed previously for fabricating bi-layer or multi-layer composite structures.

One step, 3D printed stimuli-responsive polymeric composites for shape-morphing applications

ACS Spring 2022

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