Mechano-Regulable and Healable Silk-Based Materials for Adaptive Applications

Abstract

Mechanically adaptive materials responsive to environmental stimuli through changing mechanical properties are highly attractive in intelligent devices. However, it is hard to regulate the mechanical properties of most mechanically adaptive materials in a facile way. Moreover, it remains a challenge to achieve mechano-regulable materials with mechanical properties ranging from high strength to extreme toughness. Here, inspired by the reversible nanofibril network structure of skeletal muscle to achieve muscle strength regulation, we present a mechano-regulable biopolymeric silk fibroin (SF) composite through regulating dynamic metal−ligand coordination bonds by using water molecules as competitive regulators. Efficient interfacial hydrogen bonds between tannic acid-tungsten disulfide nanohybrids and the SF matrix endow the composite with high mechanical strength and selfhealing ability. The resulting composite exhibits 837-fold change in Young's modulus (5.77 ± 0.61 GPa to 6.89 ± 0.64 MPa) after water vapor triggering, high mechanical properties (72.5 ± 6.3 MPa), and excellent self-healing efficiency (nearly 100%). The proofof-concept ultraconformable iontronic skin and smart actuators are demonstrated, thereby providing a direction for future selfadaptive smart device applications.

Self‐healing polymers for soft actuators and robots

“…This actuating process only requires the intrinsic physical nature of polymers rather than shape programming. To enhance the actuating complexity, many researchers fabricated actuators with dual‐layered or graded structures relying on light‐induced asymmetric expansion 80–86 . For instance, Zhang et al advocated the designs of hierarchy dynamic structures on the scales of molecule and micro‐nano to improve mechanical, actuating and self‐healing properties synergistically.…”

“…To enhance the actuating complexity, many researchers fabricated actuators with duallayered or graded structures relying on light-induced asymmetric expansion. [80][81][82][83][84][85][86] For instance, Zhang et al advocated the designs of hierarchy dynamic structures on the scales of molecule and micro-nano to improve mechanical, actuating and self-healing properties synergistically. The mismatch of modulus and coefficients of thermal expansion between active/inactive layers make material bends to one side once exposure to near-infrared light (NIR) stimuli.…”

Harmless photonic crystal tattoo with angle‐independent structural color based on SiO2 nanoparticles and silk fibroin

“…Researchers have also discovered a method to obtain skin-friendly and soft sericin proteins by incorporating Ca 2+ ions into SF precursor solutions. 21,22 In this study, we utilized SF solutions to coassemble with SiO 2 NPs for the fabrication of HPCT on artificial skin. The obtained HPCT displayed a vivid nonphosphorescent structural color, as the addition of SF disrupts the long-range ordering of the periodic structure.…”