Multimaterial Digital Light Processing Three-Dimensional Printing of Materials with Different Relaxation Kinetics

Covalent adaptable networks (CANs) are cross-linked polymer networks, which are able to undergo topological rearrangements due to dynamic exchange reactions under an external stimulus (typically heat), allowing these materials to be malleable, weldable, and recyclable. The temperature-dependent kinetics of dynamic exchange reactions can be tuned by varying the concentration of the dynamic links. However, decreasing the number of dynamic linkages increases the impact of diffusion factors, causing deviation from the Arrhenius-like dependence. Herein, we study the exchange dynamics in the photocurable thiol-ene CANs relying on the thiol-thioester exchange mechanism and investigate the proportion of Arrhenius behavior and Rouse diffusion on the overall stress relaxation kinetics. Materials differing substantially in their stress relaxation kinetics are printed via dual-vat multimaterial DLP 3D printing, and the creep performance of the multimaterial samples is evaluated. In addition, these multimaterial samples can be used as simple temperature-time sensors based on thermal imprinting.