Imparting superhydrophobic and biocidal functionalities to a polymeric substrate by the sonochemical method

Multifunctional substrates with superhydrophobic and biocidal properties are gaining interest for a wide range of applications; however, the production of such surfaces remains challenging. Here, the sonochemical method is utilized to impart superhydrophobicity and antimicrobial properties to a polyethylene (PE) sheet. This is achieved by sonochemically depositing nanoparticles (NPs) of a hydrophobic fluoro-polymer (FP) on the PE sheets. The polymer is a flexible, transparent fluoroplastic composed of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride in the form of a powder. The NPs of polymers are generated and deposited on the surface of the PE using ultrasound irradiation. Optimizing the process results in a homogeneous distribution of 110-200 nm of NPs on the PE surface. The coated surface displays a water-contact angle of 160, indicating excellent superhydrophobicity. This superhydrophobic surface shows high stability under outdoor conditions for two months, which is essential for various applications. In addition, metal-oxide nanoparticles (CuO or ZnO NPs) were integrated into the polymer coating to achieve antibacterial properties and increase the surface roughness. The metal oxides were also deposited sonochemically. The antibacterial activity of the FP@ ZnO and FP@CuO PE composites was tested against the bacterium Staphylococcus aureus, and the results show that the FP@CuO PE can effectively eradicate the bacteria. This study highlights the feasibility of using the sonochemical method to deposit two separate functions, opening up new possibilities for producing smart novel surfaces.