A scalable, non-chemical route to superhydrophobic PTFE surfaces via copper mould-assisted hot embossing

Durable and scalable superhydrophobic surface development without chemical coatings remains a formidable challenge in surface engineering. Present research displays a cost-effective and a physical driven approach to enable superhydrophobicity on the surface of polytetrafluoroethylene (PTFE) by integrating hierarchical roughness structures through hot embossing. Dual scale roughness asperities were generated on copper surfaces via sandblasting followed by electrochemical etching, where the etching duration varied to tailor the surface roughness. These patterns were transferred onto PTFE surfaces through hot embossing at temperature below, near and above its glass transition temperature (∼121°C), enabling assessment of roughness pattern. Surface morphology was analysed using optical profilometer and Scanning Electron Microscope, and quantified using higher-order roughness parameters, including kurtosis (R ku ) and skewness (R sk ), in addition to roughness factor (r) and solid fraction (ϕ s ). The results outline the influence of viscoelastic deformation of PTFE by the temperature in controlling the pattern transfer. Even though the hierarchical structures were enhanced by high temperatures, the pattern transfer efficiency reduce due to adhesion and mechanical interlocking effects. A clear correlation was established among surface morphology and wetting behavior, visualizing an air entrapment for valley-dominated surfaces with moderate peak sharpness and thereby reduces liquid-solid contact. PTFE surfaces had achieved a maximum water static contact angle of 151°, confirming superhydrophobicity without chemical modification. These findings demonstrate the relationship among process, morphology, and wetting to generate a scalable, industrial scale, and environment-friendly method for engineered superhydrophobic PTFE surfaces.