Preparation and Characterization of Functionalized Polyethylene Surfaces

Ralph G Nuzzo, G. Smolinsky

Research output: Contribution to journalArticlepeer-review

Abstract

We describe a procedure to modify the surface of polyethylene (PE) film using a combination of gas discharge and wet chemical techniques. This method generates high densities (1014-1016 cm-2) of a specific functionality, largely unaccompanied by other groups, in a 50-100-Å surface layer. The topography of the polymer surface remains unchanged after treatment and functions as an effective starting material for subsequent derivatization by standard synthetic chemical reactions. A plasma of either oxygen, water, or hydrogen is generated under comparable experimental conditions. In all cases a 1-2-s, 5-W, 0.2-Torr treatment produces about the same degree of surface modification as does longer treatment. High-resolution X-ray photoelectron spectroscopy (XPS) shows that either an oxygen or a water plasma produces a variety of oxidation products ranging from alcohols to carboxylic acids. Chromic acid oxidizes the plasma-oxidized surface further to give high densities of carboxylic acid groups which can be readily converted to acid chlorides and derivatized. Borane/tetrahydrofuran reduces the plasma-oxidized surface to give alcohols which can be esterified readily. Contact-angle measurements show that the water-plasma-treated PE surface has a higher surface free energy (γs ∼ 62 dyn/cm) than the oxygen-plasma-treated surface (γs ∼ 50 dyn/cm). A 5-s, ambient-temperature, 0.2-Torr, 2-W hydrogen plasma generates a significant number of quenchable radical sites. XPS spectra of this treated surface, exposed to either nitric oxide or nitrosotrifluoromethane, show that both compounds bond to the surface.

Original languageEnglish (US)
Pages (from-to)1013-1019
Number of pages7
JournalMacromolecules
Volume17
Issue number5
DOIs
StatePublished - Apr 1984
Externally publishedYes

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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