4D Printing of MXene Composites for Deployable Actuating Structures

The development of innovative materials for three-dimensional (3D) printing is creating potential opportunities for advancements in additive manufacturing (AM) technologies, including in four-dimensional (4D) printing. Through the creation of next-generation shape memory polymer composites (SMPCs), printed parts can now be bestowed with increased functionalities including the ability to transform their shape, acting as smart actuators that respond to the stimuli around them. These materials are of great interest for development of soft robotic systems, which can be quickly and affordably manufactured. In this work, a SMPC consisting of a TPU:PLA polymer blend system with embedded MXene (Ti3C2) flakes is fabricated and evaluated. The mechanical, thermal, and morphological properties prove to be greatly improved with the addition of MXene at 0.5 wt %. At higher loadings of 2 wt % MXene, the composite shows superb shape memory effect results in fast recovery to ∼98% its original position in under 14 s. Rheological behavior and thermal properties were evaluated, followed by 3D printing using material extrusion. Results show great potential of MXene-loaded composites for fast shape memory actuation in 3D/4D printed structures. The potential of such composites is demonstrated through several printed designs, which show large deformation suitable for deployable structures.