A high-efficiency way to improve the shape memory property of 4D-printed polyurethane/polylactide composite by forming in situ microfibers during extrusion-based additive manufacturing

Extrusion-based additive manufacturing was used to prepare polyurethane/polylactide (TPU/PLA) samples. The PLA phase was deformed into a microfiber structure because of the strong shear effect of extrusion-based additive manufacturing. This novel microfiber could not only reinforce considerably the matrix but was also beneficial to the shape memory property. When stretched at an appropriate temperature, the samples could maintain their deformation after cooling and recover automatically after thermal stimulation. Thus, a high-efficiency method to create 4D-printed samples by extrusion-based additive manufacturing is proposed. The effects of phase morphology and molecule structure on the shape memory cycle are also discussed.