Innovations in ionotronics have greatly facilitated the
development
of ultraflexible devices, displays, and machines. However, ionotronics
often suffer from an inherent trade-off between stretchability and
elasticity due to their viscous nature. Here, we overcome this limitation
by incorporating dimension-and-content-confined nanocrystalline crosslinks
into amorphous and molecularly entangled silk fibroin (SF) ionotronics.
The welding-entanglement network exhibited a 34-fold increase in Young’s
modulus, a 14-fold increase in tensile strength, and a 9-fold increase
in toughness compared to the same SF material without the nanocrystal
crosslinks. The welding-entanglement network also gained recoverable
hysteretic energy dissipation with hysteresis as low as 22%. The stretchability
and low hysteresis exhibited by these SF ionoelastomers far exceed
those of previously reported ionotronics and bioelastomers. These
mechanical merits, together with the inherent advantages of SF ionoelastomers,
including their multiprocessability, sustainability, biocompatibility,
and degradability, promote their applications in human–machine
interfaces and bio-functional devices.