Re-Printable, Self-Healing Polymer Networks

We report a versatile approach to designing 3D printable, re-processable dynamic covalent networks with controllable mechanical properties. The approach involves synthesis of epoxy-based oligomeric building blocks of controllable length which are then reversibly crosslinked using the Diels-Alder (DA) reaction. The networks demonstrate several features which are beneficial for additive manufacturing, such as reversible dissociation to liquids at temperatures above 110 ^oC and fast curing during fused deposition modeling. Moreover, DA reactivity of the precursor material improved interlayer adhesion during printing and enabled self-healing. Using this approach, a series of networks with glass transition temperatures controlled between -10 and 35 ^oC and the elastic moduli between 10 MPa and several GPa were demonstrated. Finally, the 3D printed networks exhibited shape-memory effects which are based on the stereochemical characteristics of DA adducts.