Wettability and Aging of Polymer Substrates after Atmospheric Dielectrical Barrier Discharge Plasma on Demand Treatment

摘要

Plasma treatment is a commonly used technology to modify the wetting behavior of polymer films in the production process for, e.g., printed electronics. As the effect of the plasma treatment decreases in time, the so-called "aging effect", it is important to gain knowledge on how this effect impacts the wetting behavior of commonly used polymers in order to be able to optimize production processing times. In this article the authors study the wetting behavior of polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polycarbonate (PC), fluorinated ethylene propylene (FEP) and polyimide (PI) polymer films after plasma treatment in time. The plasma treatment was performed using a novel maskless DBD plasma patterning technology, i.e., μPlasma Printing, at atmospheric pressure under nitrogen atmosphere. After treatment, the samples were stored at room temperature at 30%-40% relative humidity for up to one month. An increase in wettability is measured for all polymers directly after μPlasma Printing. The major increase in wettability occurs after a small number of treatments, e.g., low energy density. More treatments show no further beneficial gain in wettability. The increase in wettability is mainly due to an increase in the polar part of the surface energy, which can probably be attributed to chemical modification of the surface of the investigated polymers. With the exception of FEP, during storage of the plasma treated polymers, the wettability partially declines in the first five days, after which it stabilizes to approximately 50% of its original state. The wettability of FEP shows little decline during storage. As the storage time between production steps is mostly under two days, μPlasma Printing shows good promise as a pre-treatment step in the production of printed electronics.