3D-printing of dynamic self-healing cryogels with tuneable properties
We report a novel synthetic and processing methodology for the preparation of doubly dynamic, self-healing, 3D-printable macroporous gels. 3D-printable oxime hydrogels were prepared by cross-linking poly(n-hydroxyethyl acrylamide-co-methyl vinyl ketone) (PHEAA-co-PMVK) with a bifunctional hydroxylamine. 3D-printed oxime hydrogels were subjected to post-printing treatment by thermally induced phase separation (TIPS), which facilitated the formation of hydrogen bonding and oxime cross-links, and dramatically increased the mechanical strength of soft oxime objects in a well-controlled manner by up to ∼1900%. The mechanical properties of the cryogels were tuned by freezing conditions, which affected the microstructure of the cryogels. These doubly dynamic 3D-printed cryogels are macroporous, exhibit outstanding swelling performances, and can fully, rapidly and autonomously self-heal.