Multivalent\nPolymer-Grafted Nanoparticles as Reinforcing\nFillers for 3D Printable Self-Healing Elastomers

3D printable elastomers capable of\nself-healing are attractive\nfor fabricating complex biomimetic and soft-robotic devices. While\npolymer network reorganization can be enabled with dynamic bond exchange,\nthis strategy typically faces intrinsic trade-offs between healability,\nprocessability, and mechanical performance. Thus, new material design\nstrategies that can overcome these trade-offs are needed. Here, we\nreport the use of multivalent polymer-grafted nanoparticles (PGNPs)\nas reinforcing fillers for self-healing photoresins. As each nanoparticle\nis functionalized with thousands of polymer chains engaging in multivalent\ninteractions with the surrounding elastomeric matrix, the bulk modulus\nof the composite can be increased without impairing the local segmental\nmotion of polymer chains necessary for self-healing. We also examine\nPGNP structural parameters to establish structure–property\nrelationships that permit fine-tuning of composite mechanical performance.\nFinally, these enhancements do not impair the materials’ manufacturability,\nas they can be used as feedstocks for digital light printing to produce\ncomplex and high-resolution 3D objects.