AVS 51st International Symposium
    Plasma Science and Technology Tuesday Sessions
       Session PS2-TuA

Paper PS2-TuA7
Study of the Selected Effect of Molecules Generated in N@sub 2@ and O@sub 2@ Plasma for the Surface Modification of HDPE, PVDF and PTFE.

Tuesday, November 16, 2004, 3:20 pm, Room 213B

Session: Plasma and Polymers
Presenter: F. Reniers, Universite Libre de Bruxelles, Belgium
Authors: N. Vandencasteele, Universite Libre de Bruxelles, Belgium
A. Wagner, Ames National Laboratory
H. Fairbrother, Johns Hopkins University
F. Reniers, Universite Libre de Bruxelles, Belgium
Correspondent: Click to Email
Although plasma treatments of polymers are widely used in today's industry, the surface modification mechanisms remain mostly unknown due to their complexity. The wide variety of the species generated in a plasma, combined with the specificity of a usual polymer surface make such reactions hard to understand. We have undertaken a global systematic study of the individual and synergetic effects of the species generated in a plasma on the surface modification of a series of model polymers: HDPE, PVDF, PTFE, as they illustrate the transition between C-H and C-F bonds. A modified RF plasma allowing to filter out some of the species was used@footnote 1@, as well as an in situ ion gun and a radical source. N@sub 2@ and O@sub 2@ plasmas were used, and the selected effect of N@sub2@@super +@/N@super +@, O@sub 2@@super +@/O@super +@ and O on the polymers was studied. Samples were characterized using water contact angle (WCA), AFM and XPS. The spatial distribution of the plasma species was analysed by OES. In our configuration, most of the particles reaching the polymer are neutrals and electrons. Results show that the nature and amount of the functionalities grafted, the roughness and the WCA strongly depend on the starting polymer, and on the nature of the incident beam. For instance, the functions grafted on HDPE using the plasma neutrals are mostly C=N groups, whereas nitrogen ion treatment leads to a majority of amines. The N@sub 2@ plasma treatment of PTFE induces defluorination of the polymer, with rapid increase of the nitrogen content. New chemical functions, and CF@sub 3@ groups are evidenced. The decrease of the WCA is directly correlated to the surface amount of nitrogen. On the contrary, exposure of PTFE to N ions leads to no significant grafting. Oxygen treatment of HDPE and PVDF lead to an increase of surface energy, but on PTFE a super-hydrophobic surface is created. @FootnoteText@ @footnote 1@ A. Wagner, D.H. Fairbrother, F. Reniers, plasma and polymers, 8 (2003) 119.