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Surface composition, chemistry, and structure of polystyrene modified by electron-beam-generated plasma
Evgeniya H Lock1, Dmitri Y Petrovykh, Paul Mack
1Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375, USA. evgeniya.lock@nrl.navy.mil
Langmuir : the ACS Journal of Surfaces and Colloids
|April 8, 2010
Summary
Electron-beam plasmas modify polystyrene (PS) surfaces, introducing chemical changes. Hydrophobic recovery in Ar/O(2) and Ar/N(2) treated surfaces is due to polymer fragment diffusion, not contamination.
Area of Science:
- Materials Science
- Polymer Chemistry
- Surface Science
Background:
- Polystyrene (PS) is a widely used polymer.
- Surface modification techniques are crucial for tailoring material properties.
- Plasma treatments offer a versatile method for surface functionalization.
Purpose of the Study:
- To investigate the effects of electron-beam-generated plasmas on polystyrene (PS) surfaces.
- To analyze chemical and morphological changes induced by different plasma environments (Ar/O2, Ar/N2, Ar/SF6).
- To understand the mechanisms of surface property evolution, including hydrophobic recovery.
Main Methods:
- Electron-beam-generated plasmas for surface treatment.
- Contact angle goniometry for surface energy analysis.
- Atomic Force Microscopy (AFM) for surface morphology.
- X-ray Photoelectron Spectroscopy (XPS) and Reflection Electron Energy Loss Spectroscopy (REELS) for chemical composition.
- Angle-resolved XPS (ARXPS) for depth profiling.
Main Results:
- Plasma treatments minimally increased surface roughness.
- Ar/O2 and Ar/N2 plasmas introduced oxygen and nitrogen, respectively, leading to initial hydrophilicity.
- Ar/SF6 plasma introduced fluorine, resulting in stable hydrophobicity.
- Hydrophobic recovery in Ar/O2 and Ar/N2 treated PS was attributed to the reorientation of bulk polymer fragments.
- Plasma-induced modifications were confined to the top 3-4 nm, preserving bulk PS structure.
Conclusions:
- Electron-beam plasmas effectively modify PS surface chemistry.
- The mechanism of hydrophobic recovery is diffusion of undamaged polymer fragments.
- Plasma modifications are surface-confined, preserving the bulk properties of polystyrene.
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