Tuning structure in 3D-printed scaffolds of polylactide by extensional stress and its influence on properties

Abstract

In response to the increasing demand for biological scaffolds for bone defect repair in tissue engineering, fabricating biocompatible porous scaffolds with controllable mechanical properties has been a significant challenge. In this work, we successfully designed a unique Triply Periodic Minimal Surface (TPMS) structure along with delicate uniaxial stretching on it, which was integrated as a “three-dimensional (3D) printing-uniaxial stretching” strategy. The lightweight (0.505 g/cm3) and superior impact strength (25.63 ± 1.4 kJ/m2) of the 3D-printed polylactide (PLA) scaffold are attributed to the smooth and continuous porous structure, which is also beneficial for the uniformly deformed during the uniaxial stretching. With the increase of the draw ratio, the volume proportion of the inner hollow porous progressively expanded, allowing the density to decrease from 0.505 g/cm3 to 0.428 g/cm3 (a decrease of 15.2%). Crucially, the mechanical properties of the 3D-printed porous scaffold are significantly improved after uniaxial stretching. Impact strength and yield strength increased significantly to 400% and 355% of the original 3D-printed PLA scaffold, climbing to 101.16 ± 1.68 kJ/m2 and 13.88 ± 0.68 MPa, respectively. The relative modes of action are discussed in detail. This work provides a novel method to improve the application range of 3D-printed porous scaffolds in biomedical applications of tissue engineering and engineering materials.