Comparative Study of the Superhydrophobic‐Modification of Silicone Rubber Surfaces by CF₄ ICP and CCP

Abstract

Super‐hydrophobic surface‐modification of silicone rubber (SIR) as an outdoor insulator by CF4 radio frequency (RF) inductively coupled plasma (ICP) and capacitively coupled plasma (CCP) has been studied. X‐Ray photoelectron spectroscopy, atomic force microscopy, and static contact angle measurements were employed to characterize the changes of the surface chemical composition, topography, and hydrophobicity. The results show that etching or ablation and fluorination are parallel and competitive during both treatments. The improvement of hydrophobicity is ascribed to the coaction of the increase of surface roughness and the introduction of fluoric groups (CCFn) or structures (SiF and SiF2). It is also found that the ratio of [SiF]/[CF] and the increase of surface roughness of the SIR treated by CCP are higher than that by ICP, which leads to a greater hydrophobic modification effect by the CCP process.

On the surface performance of superhydrophobic silicone rubber specimens fabricated by direct replica method

“…Finally, air corona-treatment of smooth SIR resulted in minor decrease of its hydrophobicity (θ s =114°±8°). Contrary, Gao and coworkers, while studding surface modification of the originally smooth SIR specimens by radio frequency capacitively coupled plasma (RFCCP) generated in CF 4 , observed etching and ablation of the smooth SIR surface leading to increase of its roughness accompanied by introduction of fluoric groups, leading to the increase of θ s up to 150° [23]. Garra et al while investigating plasma etching of smooth PDMS for microfluidic systems also found out that the dry O 2 /CF 4 plasma process leads to increase of roughness [24].…”

Fluorine‐Free Superhydrophobic Microstructured Films Grown by PECVD

“…[13] Surface energy can then be reduced by a self-assembled monolayer (SAM) of chlorosilanes, [5] thiols, [14] fluorosilanes, [4] or by plasma fluorination. [15][16][17] Indeed, plasma treatments are often used to increase the WCA by surface grafting of elemental fluorine or by creating a new fluorinecontaining top layer. A selective etching to modify a polydimethylsiloxane surface by a SF 6 plasma, [18] or fluorine grafting of a low density polyethylene surface by a CF 4 plasma, [19] are two examples.…”

“…The second step -i.e., surface modification by fluorine grafting -can also be replaced by a PECVD step to make a new deposited film, with a low surface energy, grown on the rough surface. [13][14][15][19][20][21][22][23][24][25][26] PECVD of a C 4 F 8 -based plasmapolymer is an example. Currently, one article relates the fabrication of a superhydrophobic surface by a one-step PECVD using a fluorinefree precursor, directly from a flat surface, using an atmospheric pressure plasma jet system.…”

Ehrungen

“…Some examples are phase separation,3 sol‐gel silica‐based films,4 isolated nanodots formed by induced crystallization,5 deposition of inorganic nanoparticles,6, 7 controlled thermal treatment to obtain nanoparticles from an adsorbed precursor,8 chemical grafting deposition of a monolayer of polystyrene spheres as templates,9, 10 electrochemical deposition,11 controlled growth of carbon nanotubes normal to the surface,12 and graphite oxide from a grapheme surface 13. Surface energy can then be reduced by a self‐assembled monolayer (SAM) of chlorosilanes,5 thiols,14 fluorosilanes,4 or by plasma fluorination 15–17. Indeed, plasma treatments are often used to increase the WCA by surface grafting of elemental fluorine or by creating a new fluorine‐containing top layer.…”