Nanofibrillar Surfaces via Reactive Ion Etching

Abstract

The reactive ion etching of poly(ethylene terephthalate) using various gas compositions was examined. A radio frequency power supply operating at 30 kHz was used to produce plasmas from the following gases and 50:50 gas mixtures: Ar, N2, O2, Ar-N2, Ar-O2, and N2-O2. Exposure times were typically 10, 20, and 30 min. The relatively inert gases and gas mixtures (Ar, N2, Ar-N2) produced a polygonal pattern of protrusions surrounding shallow cavities. In contrast, the presence of oxygen or oxygen-containing plasmas invariably imposed a fibrillar structure on these polygons in which "nanofibrils" typically originated at the triple points of several neighboring polygons. The dimensions of these fibrils varied with the exposure time but were up to 300 nm in length and approximately 20 nm in diameter. Atomic force microscopy was used to quantify the surface roughness and show that the inert gas compositions (Ar, N 2, Ar-N2) produced statistically indistinguishable values of Ra (14.1 ( 1.7, 15 ( 2.5, 14.2 ( 2.9 nm) significantly larger than those of the as-received film. The pure oxygen-etched films have Ra values approximately twice as large as those of the other gas compositions. Prior work by Nie et al. suggests that films consisting of etchingresistant, low-molecular-weight fragments can form under these conditions. We find that surface physics normally associated with thin polar films on apolar substrates adequately describes the origin of the observed nanofibrils. Prior surface deformation has an additional influence on fibril spacing and density.

Superhydrophilic and superhydrophobic nanostructured surfaces via plasma treatment

“…In semicrystalline polymers, nanometer-sized roughness was observed on cellulose fibres after oxygen plasma treatment [1]. Microsized aligned ridges [2], nanosized bumps [3] and fibrils [4] with 20 nm in diameter and up to 300 nm in length were observed after oxidative plasma treatment of PET films. Nanotextures have also been observed in amorphous polymers, i.e.…”

Polymer Nanoengineering for Biomedical Applications

“…Nanofibrillar surfaces on polymers can be formed through RIE using various gas compositions. 107 Figure 3 shows PET surface etched with a 50:50 O 2 -N 2 gas mixture for 30 min under a radio frequency power supply operating at 30 kHz. The dimensions of these fibrils are around 300 nm in length and 20 nm in diameter.…”

Effect of absorbed moisture on the atmospheric plasma etching of polyamide fibers

“…The predominant active species in radio frequency plasma are positive ions and photons, with ability of breaking primary chemical bonds and inducing cross-linking [26,27]. The extent of degradation in plasma etching is closely correlated to the chemical structure of the polymer at a given plasma working condition [5,[28][29][30][31][32]. It was reported that polymeric structures containing oxygen were more susceptible to plasma while polymers with high crystal and stable structures were more resistant to oxidation and etching [30,32].…”