Plasma-jet-induced programmable wettability on stretchable carbon nanotube films

Abstract

Stretchable surfaces with site-selective and degree-controlled wettability are indispensable for various applications ranging from self-cleaning to droplet manipulation and drag reduction; however, superwettable surfaces or patterns with robust stretchability are seldom demonstrated to date. To address such challenging issue, herein, we proposed a facile approach to programmatically realize extreme wetting-contrast patterning of stretchable carbon nanotubes/polydimethylsiloxane (CNTs/PDMS) using atmospheric micro-plasma jet (μPJ). The μPJ had been used to engineer both superhydrophobicity and superhydrophilicity through exploiting surface hierarchical roughness under a shielding nitrogen gas and oxygenic functional groups in atmosphere, respectively, tailoring the water contact angles from ~160° to <10° ultimately. The as-prepared superhydrophobic, conductive surfaces could bear tensile strain even up to 100% and demonstrated no noticeable wettability deterioration after 1000 cyclic stretching from ε = 0% to ε = 50%. And they also presented a distinguished enduring stability in terms of exposure to air and even extreme acidic/alkaline aqueous droplets. As the randomly entangled CNTs film could respond to tensile strain, the superhydrophobic films had been successfully applied to water-repellent epidermal sensors. And hydrophilic patterns had been fabricated on the superhydrophobic surfaces as well. It can be envisioned that a variety of novel applications ranging from water/blood-repellent human-machine interfaces to in-plane microfluidic can be implemented via this powerful wettability regulation paradigm.