Architectured Silicone Vitrimers with Light-Tunable Mechanical and Self-Healing Behavior

Architectured materials synergistically harness chemical and microstructural features to create monoliths with antagonistic properties. Although it is a hallmark of biological composites, this material design concept has only recently been applied to synthetic elastomers and vitrimers. Here, we propose a light-based platform to manufacture architectured silicone vitrimers with locally tunable mechanical properties. Vitrimers are created through photocuring of polymer mixtures containing silica particles, silicone prepolymers and thiol crosslinkers. Dioxaborolane groups are incorporated in the silicone prepolymers to form dynamic bonds in the covalent adaptive network. Experiments showed that the mechanical properties and self-healing behavior of the silicone vitrimers are strongly influenced by the illumination conditions used during photo-curing. This dependence is exploited to manufacture architectured silicone vitrimers combining high stretchability and locally programmable mechanical stiffness. The high stretchability, tunable local properties and adaptive nature of these polymers makes them attractive for applications in soft robots, biomedical implants, and wearable devices.