Surface Modification of Fluorine-containing Polymers by Atmospheric Pressure Plasma Jet with Negative Substrate Biasing

Abstract

Fluoropolymers are difficult materials to modify the surfaces because of strong C-F bonds. In this study, the surface modification of fluoropolymer films such as polytetrafluoroethylene (PTFE) with amino groups was performed by using He/NH 3 gas mixture atmospheric pressure plasma jets with negatively-biased substrate. It is expected that the ion bombardment effect onto the polymer surface due to negative substrate bias will make dangling bonds over the polymer surface and eventually promote the surface modification. From XPS analysis, we confirmed the breaking C-F bonds and creating C-C, C=O or C-N bonds in C 1s spectrum and increasing nitrogen-containing functional groups in N 1s spectrum. Fluorescence patterns were observed on the amino group functionalized PTFE surface by using the fluorescent dyes selectively connecting with the amino groups. With a spectrophotometric method, the surface concentration of amino groups introduced onto the PTFE surface was evaluated to be roughly 3.86 nmol/cm 2 .

Rapid Functionalization of Polytetrafluorethylene (PTFE) Surfaces with Nitrogen Functional Groups

“…Atmospheric pressure plasma was used for surface modification of PTFE by Nagatsu et al [23]. The plasma jet was sustained in helium with the addition of ammonia.…”

Plasma polymerization using helium atmospheric‐pressure plasma jet with heptylamine monomer

“…Interest in the use of atmospheric pressure plasma jets (APPJs) as a method of surface functionalization has continued to grow over recent years . Much of the work focuses on operating in air, which enables processing to be conducted more cost effectively than in systems requiring a vacuum chamber.…”

Grafting of acrylic acid onto microwave plasma-treated polytetrafluoroethylene (PTFE) substrates

“…1,2,[17][18][19][20][21][22] However, plasma-based methods have been heavily explored since it is a fast and efficient technique to improve surface characteristics without changing the bulk properties of the material. [23][24][25][26] Among the different plasma techniques, it can affect the surface by cleaning, etching, cross-linking, inducing physical and chemical changes as well as biological modification. [27][28][29] In addition, the plasma sheath usually conforms to the surface profile which realizes uniform treatment even for complex surface geometries.…”