Multivalent Polymer-Grafted Nanoparticles as Reinforcing Fillers for 3D Printable Self-Healing Elastomers

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