Carbon Framework-Reinforced Biomimetic PTFE/C Structures via PEGDA-Assisted DLP Printing and Carbon Sintering for Enhanced Superhydrophobicity and Wear Resistance

Polytetrafluoroethylene (PTFE) is renowned for its exceptional chemical inertness and hydrophobicity. However, the high melt viscosity, low surface energy, and high cooling shrinkage of PTFE make it difficult to fabricate fine three-dimensional (3D) structures through photopolymerization molding. Meanwhile, due to the mechanical properties of PTFE, such as low hardness and low elastic modulus, the wear resistance of its structure is usually poor. In this study, we propose an effective strategy to enhance both wear resistance and superhydrophobicity in 3D-printed PTFE/C structures by controlling the carbon residue during the sintering process. To achieve the refined structure of PTFE, a photo-cross-linkable PTFE/PEGDA ink was developed, in which PEGDA acts as a photocurable scaffold to enable high-resolution DLP printing of PTFE nanoparticles. Furthermore, inspired by the microarray of cicada wings, a needle-repellent structure with a water contact angle (CA) exceeding 150° was printed using a PTFE-based ink. Based on the above structure, the carbon residue in PTFE/PEGDA was controlled by the sintering process to further enhance the wear resistance and superhydrophobicity of the structure. These results indicated that the sintered needle-repellent structure can still maintain excellent hydrophobic properties with 1000-grit sandpaper under a load of 100 g for 20 cycles. The performance conflict between superhydrophobicity and wear resistance of the PTFE/C structure has been effectively alleviated through the printed needle-repellent structure and controlled carbon residue. Furthermore, even after 2 weeks of immersion in strongly acidic and alkaline environments, the structure morphology remains stable. These excellent features of the needle-repellent structure make it applicable to a wide range of applications, such as droplet manipulation, oil-water separation, and fog harvesting.