Superhydrophilic properties of plasma-treated Posidonia oceanica

► Plasma treatment of Posidonia oceanica resulted to stable superhydrophilic surfaces. ► O2 plasma treatment showed greater sample weight loss than Ar plasma treatment. ► Surface roughness effects vary for the O2 and Ar plasma treatment. ► Increase in the surface roughness leads to the decrease in the water contact angle. ► CH2 and C-H groups were absent from the FT-IR of the superhydrophilic samples.