Robust Underwater Air Layer Retention and Restoration on <i>Salvinia</i>-Inspired Self-Grown Heterogeneous Architectures.

Abstract

<i>Salvinia's</i> long-term underwater air layer retention ability has inspired researchers to develop artificial microstructures. However, <i>Salvinia</i> 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 <i>Salvinia</i> 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 <i>Salvinia</i>-inspired artificial structures and reveals the underlying mechanism of the robust air retention and recovery capability of <i>Salvinia</i> leaves in extreme environments.