Qinmin Pan

A superhydrophobic aerogel with robust self-healability

Self-healing is an effective strategy to improve the durability of a superhydrophobic surface, but a challenge remains in repairing its multi-scale structures and wettability simultaneously after damage. Here we report a self-healable superhydrophobic aerogel that spontaneously restores its superhydrophobicity, microstructure and macroscopic configuration simultaneously after physical or chemical damage. The superhydrophobic aerogel is fabricated by decorating an alginate-based aerogel with silver nanoparticles and octadecylamine (ODA). Once the aerogel is scratched or cut, it repairs both hierarchical structures and configuration integrity autonomously via wetting/heating processes, resulting in the recovery of superhydrophobicity and mechanical properties. Even after being etched with O2 plasma, it regains its superhydrophobic properties through a simple heat treatment. The robust healability is attributed to the dynamic catechol–Fe coordination as well as thermally induced rearrangement of ODA molecules. This concept of robust healability offers a new insight into the design of robust superhydrophobic surfaces aiming at various technological applications.

Mussel-inspired healing of a strong and stiff polymer

Self-healability will greatly improve the reliability, service life and maintenance of synthetic materials. However, it remains a big challenge to realize the self-healing of a strong and stiff polymer due to its poor molecular mobility. Inspired by the hardness and self-healability of the cuticle of mussel byssal threads, here we demonstrate that a stiff and strong polymer can heal itself through dynamic metal–ligand interactions. The polymer is comprised of nitrocatechol-substituted chitosan cross-linked by catechol–Fe complexation, which exhibits a tensile strength (63.6 ± 2.2 MPa) and an elastic modulus (862.6 ± 31 MPa) comparable to or even better than those of common engineering plastics. When subjected to multiple physical damages, the stiff polymer is able to recover its configuration integrity and mechanical properties autonomously via pH-induced coordination between Fe3+ and the catecholic moiety. Moreover, the polymer also exhibits interesting renewability, flame retardancy and solvent-tolerance. The application of the polymer is demonstrated by a weight-bearing test. Our investigation offers a bio-inspired strategy to design healable rigid polymers that have potential applications in various technological fields.

An all-in-one self-healable capacitor with superior performance

Excellent self-healability is considered as a critical element for next-generation flexible/wearable energy-storage devices. However, realizing superior electrochemical performances remains a big challenge for such devices because self-healability intrinsically offsets their basic energy-storage functions. Here we demonstrate that the conflict can be effectively addressed for a supercapacitor via rationally designing its device configuration at a molecular level. The capacitor is fabricated by in situ integrating polyaniline (PANI) and H2SO4 solution into a single network comprising the copolymer of vinylimidazole and hydroxypropyl acrylate (PVH). The all-in-one configuration combines fast charge-carrier transportation, good structural durability and excellent self-healability. Consequently, the resulting capacitor delivers a high specific areal capacitance and rate capability superior to its counterparts, but also maintains ultra-long cycling life even after breaking/healing 10 times. This example of configuration engineering offers a new and promising avenue to design self-healable energy-storage devices with outstanding performances.