Self-cleaning features of plasma-treated surfaces with self-assembled monolayer coating

Abstract

A biomimic surface was coated onto a poly(tetrafluoroethylene) (PTFE) substrate. The coated PTFE surface was found to have nanoscale roughness and high hydrophobicity. In the first preparation step, the PTFE surface was modified by plasma etching. A self-assembled monolayer (SAM) of octadecyltrichlorosilane (ODTS) was then deposited onto the modified surface with a thickness of a 2-3 nm. This surface was found to have self-cleaning features similar to those of a lotus leaf. The self-cleaning features were confirmed by comparing the contact and sliding angles of the original PTFE surface, a PTFE surface plasma treated, and a PTFE surface plasma treated and SAM coated. The PTFE surface treated with plasma and SAM coated had an increased contact angle and a decreased sliding angle compared with the other surfaces. It also exhibited increased stability and slow aging. The quantity of oxygen-containing groups that can be greatly influenced by plasma treatment, SAM coating, and aging, seems to play an important role in surface modification.