Fabrication of Lotus Leaf-Inspired Superhydrophobic Chitosan-Based Membranes with Enhanced Mechanical Durability and Surface Performance

The use of low-cost and naturally abundant biopolymers to fabricate superhydrophobic membranes has attracted increasing attention due to their environmental friendliness and broad application potential. However, the micronano rough microstructures required for water repellency are often fragile and prone to abrasion under mechanical stress, limiting their durability and practical application. In this study, lotus leaf-inspired superhydrophobic chitosan (CS)-based membranes with enhanced mechanical durability and surface performance were fabricated by incorporating hydrophobic chitosan microspheres (CM-SS) modified with sodium stearate into the films. The introduction of CM-SS not only reinforced the hierarchical surface roughness but also strengthened the interfacial adhesion through hydrogen bonding with the CS matrix. The optimized membrane (CPMPS) exhibited a root-mean-square (RMS) surface roughness of 3.98 μm, which exceeded that of the natural lotus leaf used in our study (3.11 μm). It demonstrated a high water contact angle of 157° and a low sliding angle of 8°. Mechanical tests showed that the film exhibited a tensile strength of 8.7 MPa and an elongation at break of 49.4%. Notably, the membrane retained a contact angle of 148° after 50 cycles of sandpaper abrasion and 141° after 20 tape-stripping cycles, both of which were higher than the control membrane without CM-SS. In addition, the membrane demonstrated remarkable self-cleaning performance and up to 90% oil-water separation efficiency. These findings indicate that the integration of CM-SS effectively enhances both the mechanical properties and the surface performance of superhydrophobic membranes. This green and scalable fabrication strategy holds great promise for sustainable applications, such as oil-water separation and protective coatings.