Highly Recyclable, Mechanically Isotropic and Healable 3D-Printed Elastomers via Polyurea Vitrimers
Wei Niu, Zhen Zhang, Qiyi Chen, Pengfei Cao, Rigoberto C. Advíncula
Abstract
Delamination of three-dimensional (3D) printed polymer materials by fused deposition modeling (FDM) is a long-standing challenge in additive manufacturing (AM). With numerous efforts devoted to modification of commercially available thermoplastic FDM filaments, developing printing polymeric materials with new chemical design that could intrinsically improve interlayer adhesion, especially combined with other benefits, is in high demand. Herein, we developed a polyurea vitrimer with heat-driven malleability, which is printed to different 3D geometries using FDM. Significantly improved interlayer adhesion was observed by post-annealing the printed samples close to its topology-freezing transition temperature upon which fast associative dynamic covalent bonds exchange reaction occurs. Isotropic mechanical properties were achieved as demonstrated with printed tensile samples with different infill directions. The printed materials could be fully recycled for five generations with retained mechanical properties. Furthermore, the mechanical performance of the printed sample could also be repaired after damage.