Bioinspired dual-wettability copper surfaces

Bioinspired wettability surfaces have attracted significant attention for applications in directional droplet transport, condensation-water harvesting, and thermal management. In this study, a simple and low-cost sticker-assisted masking technique was developed to fabricate dual-wettability patterned copper surfaces through selective stearic acid (SA) functionalization. This lithography-free approach enabled the formation of patterned hydrophobic and hydrophilic regions on a single copper substrate. FE-SEM analysis revealed clear morphological differences between the functionalized and non-functionalized regions; while image-based surface roughness analysis performed using Gwyddion software (version 2.71) demonstrated that the hydrophobic region possessed approximately two-fold higher roughness than hydrophilic region, confirming the formation of a hierarchical surface morphology. EDS and ATR-FTIR analyses verified successful SA functionalization through increased carbon content and characteristic CH ₂ , C=O, and C–O absorption bands. Static water contact angle measurements yielded contact angles of 85°, 99°, and 72° for the hydrophilic, hydrophobic, and dual-patterned surfaces, respectively, confirming the successful development of a wettability contrast. The observed wettability behavior was attributed to the combined effects of surface-energy chemistry, copper oxide formation, and hierarchical surface morphology. The fabricated dual-wettability surfaces exhibited favorable droplet interaction characteristics, demonstrating their potential for condensation water enhancement, and heat transfer applications. Overall, the proposed fabrication strategy offers a facile, scalable, and cost-effective route for developing bioinspired, dual-wettability copper surfaces for advanced surface engineering applications.