Additive manufacturing of vitrimers: Interplay between polymer physics and processing approaches

Associative covalent adaptable networks (ACANs) bridge the gap between thermosets and thermoplastics and are an exciting class of materials for additive manufacturing (AM) applications. Due to the presence of dynamic covalent networks, ACANs exhibit excellent reprocessability and self-healing characteristics while retaining mechanical performance and chemical resistance. This review explores the latest trends in 3D-printed ACANs, focusing on material formulations and printing techniques. The stimuli-responsive bond exchange behavior of ACANs and associated relaxation mechanisms are explored in relation to printing process physics. The crucial impact of the thermal processing window and rheological properties on the printability of ACANs are highlighted, emphasizing their role in ensuring consistent interlayer bonding and desired printed part morphology. Moreover, the effect of reprocessing cycles on printability is evaluated in relation to the microstructural evolution of the covalent linkages. The fundamental insights into structure-process-property relationships gained from this review will help develop a framework for predicting printing parameters based on subtle differences in ACAN chemistry. Finally, we underscore the existing challenges associated with ACAN-based AM while proposing future research directions in the topic. By combining the unique advantages offered by ACANs and AM, it is possible to manufacture high-performance, reprocessable parts for functional applications across industries such as automotive, biomedical devices, and electronics.