Surface modification of polymeric materials by cold atmospheric plasma jet

A Toth,K.G Kostov,T.M.C Nishime,A.H.R Castro,L.R.O Hein

doi:10.1016/j.apsusc.2014.07.009

A Toth, K.G Kostov + Show 3 more

Open Access

https://doi.org/10.1016/j.apsusc.2014.07.009

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Abstract

• We investigate polymer surface modification by atmospheric pressure plasma jet APPJ. • Jet operation conditions for uniform surface modification were determined. • The APPJ added O atoms to the polymer surface and also enhanced the roughness. • The degree of polymer surface modification by APPJ and DBD were compared. • The APPJ is more efficient in attaching O atoms and produces less polymer fragments. In this work we report the surface modification of different engineering polymers, such as, polyethylene terephthalate (PET), polyethylene (PE) and polypropylene (PP) by an atmospheric pressure plasma jet (APPJ). It was operated with Ar gas using 10 kV, 37 kHz, sine wave as an excitation source. The aim of this study is to determine the optimal treatment conditions and also to compare the polymer surface modification induced by plasma jet with the one obtained by another atmospheric pressure plasma source – the dielectric barrier discharge (DBD). The samples were exposed to the plasma jet effluent using a scanning procedure, which allowed achieving a uniform surface modification. The wettability assessments of all polymers reveal that the treatment leads to reduction of more than 40° in the water contact angle (WCA). Changes in surface composition and chemical bonding were analyzed by x-ray photoelectron spectroscopy (XPS) and Fourier-Transformed Infrared spectroscopy (FTIR) that both detected incorporation of oxygen-related functional groups. Surface morphology of polymer samples was investigated by Atomic Force Microscopy (AFM) and an increase of polymer roughness after the APPJ treatment was found. The plasma-treated polymers exhibited hydrophobic recovery expressed in reduction of the O-content of the surface upon rinsing with water. This process was caused by the dissolution of low molecular weight oxidized materials (LMWOMs) formed on the surface as a result of the plasma exposure.

Highlights

Non-equilibrium atmospheric pressure plasmas [1,2,3,4] have attracted considerable attention because they require low capital cost, can be implemented in a continuous production line and due to their ability to generate highly reactive chemical species at ambient gas temperature [5]
The x-ray photoelectron spectroscopy (XPS) and Fourier-Transformed Infrared spectroscopy (FTIR) analysis reveal that both processes led to formation of alcohols, carbonyls and carboxylic acids on the surface of each polymer sample
The plasma exposure results in alteration of the surface morphology mostly through formation of polar low molecular weight oxidized materials (LMWOMs), which agglomerates into nodule-like structures

Summary

Introduction

Non-equilibrium atmospheric pressure plasmas [1,2,3,4] have attracted considerable attention because they require low capital cost, can be implemented in a continuous production line and due to their ability to generate highly reactive chemical species at ambient gas temperature [5]. Plasma plumes are a kind of atmospheric pressure gas discharges where the plasma (usually obtained from a noble gas) is extended beyond the plasma generation region into the surrounding ambience [4,6,7]. The interaction between the plasma plume and the surrounding atmosphere gives rise to different reactive species that may not be present in the discharge region [10,11].

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