Robust Underwater Air Layer Retention and Restoration on Salvinia-Inspired Self-Grown Heterogeneous Architectures

Salvinia's long-term underwater air layer retention ability has inspired researchers to develop artificial microstructures. However, Salvinia has an exquisite combination of a complicated hollow structure and heterogeneous chemical properties, which makes artificial reproduction beyond the capabilities of traditional fabrication techniques. In addition, under extremely low underpressure conditions, the mechanism of retention and restoration of the underwater air layer of Salvinia remains unclear. Herein, by combining the shape memory polymer top-constrained self-branching (TCSB) and hydrophilic SiO2 microspheres trapping, four-branch hollow microstructures with heterogeneous chemical properties are fabricated. By applying underpressure, the crucial role of hydrophilic apexes is unveiled in air layer restoration. Through the calculation of the surface energy, the underlying mechanism is well interpreted. This study holds great promise for developing Salvinia-inspired artificial structures and reveals the underlying mechanism of the robust air retention and recovery capability of Salvinia leaves in extreme environments.

Automated summary

This study successfully fabricated hollow microstructures with heterogeneous chemical properties by combining shape memory polymers and hydrophilic microspheres, and revealed the crucial role of hydrophilic apexes in air layer restoration.