Turning EDM Waste into Superhydrophobic Hierarchical Particles with Photothermal Icephobic Properties

Superhydrophobic surfaces demonstrate efficacy in anti-icing and deicing applications; however, traditional methods for fabricating hydrophobic nanoparticles typically involve intricate synthesis processes, hazardous chemical modifications, and significant energy consumption. This study demonstrates a waste-to-resource strategy, wherein carbonaceous residues generated during electrical discharge machining (EDM) in polyalphaolefin (PAO) are transformed into intrinsically hydrophobic hierarchical particles. SEM, XPS and FTIR analyses reveal that the residues comprise alkane-type organic compounds and metal-derived fragments resulting from PAO decomposition at elevated temperatures, demonstrating intrinsic superhydrophobicity with contact angles of approximately 154°. Superhydrophobic surfaces were constructed by embedding particles into a PDMS adhesive by using a straightforward blade-coating process, eliminating the need for additional nanoparticle synthesis or chemical treatment. The resulting coatings exhibit moderate mechanical durability and robust UV-light stability. Moreover, they possess significant photothermal activity, with temperatures surpassing 45 °C within 15 min under simulated solar illumination. Additionally, they demonstrate superior icephobic properties, increasing the freezing time from approximately 240 s on bare copper to around 950 s and facilitating complete deicing around 27 s. This method provides an efficient, environmentally friendly, and scalable means of producing multifunctional photothermal icephobic coatings while also effectively utilizing EDM waste effectively.