Novel Nanostructured Coating on PDMS Substrates Featuring High Resistance to Urine

Artificial urinary devices are commonly employed to restore the lost functionalities of the urinary system, due to diseases, disfunctions or organ resections. However, the long-term operation of these devices in the urinary system is affected by encrustations. In this paper, three different nanostructured coatings, based on diamondlike carbon (DLC), molybdenum disulfide (MoS₂) and Tungsten disulfide (WS₂), were deposited on polydimethylsiloxane substrates, an elastomer suitable for coating different kinds of urinary devices, and tested in terms of resistance to urinary encrustations. DLC coatings were deposited using plasma enhanced-chemical vapor deposition (T < 180 °C), whereas MoS₂ and WS₂ coatings were achieved through self-assembly at room temperature. All coatings showed good adhesion and stability on PDMS substrate over one month, relatively small roughness, a strongly hydrophobic behavior, and low surface energy. After immersion in artificial urine formulations and continuous mechanical agitation for 4 weeks, WS₂ coating resulted the most resistant to encrustations. This material had been never investigated in the urinary context. Our results pave the way to the adoption of WS₂ coatings for developing long-lasting stable urinary devices.