Improvement of Nanostructured Polythiophene Film Uniformity Using a Cruciform Electrode and Substrate Rotation in Atmospheric Pressure Plasma Polymerization.

Jae Young Kim,Hyo Jun Jang,Gyu Tae Bae,Heung-Sik Tae,Eun Young Jung,Choon-Sang Park

doi:10.3390/nano12010032

Jae Young Kim, Hyo Jun Jang + Show 4 more

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https://doi.org/10.3390/nano12010032

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Abstract

In atmospheric pressure (AP) plasma polymerization, increasing the effective volume of the plasma medium by expanding the plasma-generating region within the plasma reactor is considered a simple method to create regular and uniform polymer films. Here, we propose a newly designed AP plasma reactor with a cruciform wire electrode that can expand the discharge volume. Based on the plasma vessel configuration, which consists of a wide tube and a substrate stand, two tungsten wires crossed at 90 degrees are used as a common powered electrode in consideration of two-dimensional spatial expansion. In the wire electrode, which is partially covered by a glass capillary, discharge occurs at the boundary where the capillary terminates, so that the discharge region is divided into fourths along the cruciform electrode and the discharge volume can successfully expand. It is confirmed that although a discharge imbalance in the four regions of the AP plasma reactor can adversely affect the uniformity of the polymerized, nanostructured polymer film, rotating the substrate using a turntable can significantly improve the film uniformity. With this AP plasma reactor, nanostructured polythiophene (PTh) films are synthesized and the morphology and chemical properties of the PTh nanostructure, as well as the PTh-film uniformity and electrical properties, are investigated in detail.

Highlights

Atmospheric pressure (AP) plasma polymerization is a synthesis method in which vaporized monomer molecules successively interact with charged particles and excited species in nonthermal plasma at AP to generate various radicals and reactive species, react with each other, and form various polymers [1,2,3,4,5,6,7]
A 0.5 mm-diameter tungsten wire was used as the power electrode and covered with a glass capillary, and 20 mm was left exposed in the center of the wire for plasma generation
We proposed an AP plasma reactor with a cruciform electrode s that had the advantage of an easy spatial expansion of the plasma medium, and gated the morphological and chemical properties of the deposited PTh film u

Summary

Introduction

Atmospheric pressure (AP) plasma polymerization is a synthesis method in which vaporized monomer molecules successively interact with charged particles and excited species in nonthermal plasma at AP to generate various radicals and reactive species, react with each other, and form various polymers [1,2,3,4,5,6,7]. By confining the plasma medium using the guided tube and the substrate stand, the spatial uniformity of the discharge gas and the monomer vapor could be ensured for a longer period of time, enabling the intensive deposition of nanostructured polymeric films onto the substrate. The AP plasma reactor with a pin-type bare electrode did not require charging and discharging of the capacitive dielectric barrier and, the AP plasma could be generated at a lower voltage. This advantage made it possible to use higher amounts of monomers in the polymerization process even during low-power plasma operation

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