Transparent Polyaniline Thin Film Synthesized Using a Low-Voltage-Driven Atmospheric Pressure Plasma Reactor

Abstract

The use of low-voltage-driven plasma in atmospheric pressure (AP) plasma polymerization is considered as a simple approach to reducing the reactivity of the monomer fragments in order to prevent excessive cross-linking, which would have a negative effect on the structural properties of the polymerized thin films. In this study, AP-plasma polymerization can be processed at low voltage by an AP-plasma reactor with a wire electrode configuration. A bare tungsten wire is used as a powered electrode to initiate discharge in the plasma area (defined as the area between the wide glass tube and the substrate stand), thus allowing plasma polymerization to proceed at a lower voltage compared to other AP-plasma reactors with dielectric barriers. Thus, transparent polyaniline (PANI) films are successfully synthesized. The surface morphology, roughness, and film thickness of the PANI films are characterized by field emission scanning electron microscopy and atomic force microscopy. Thus, the surface of the polymerized film is shown to be homogenous, smooth, and flat, with a low surface roughness of 1 nm. In addition, the structure and chemical properties of the PANI films are investigated by Fourier transform infrared spectroscopy, thus revealing an improvement in the degree of polymerization, even though the process was performed at low voltage.

A Review of Plasma Synthesis Methods for Polymer Films and Nanoparticles under Atmospheric Pressure Conditions

“…Materials in a gaseous state at room temperature are themselves applied as precursors, whereas materials that exist as liquids are mainly introduced to a plasma region as an aerosol via atomizing or bubbling with gas. GATP methods are commonly used for the deposition of polymer films [ 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 ], as this method allows in-line processing by moving either the APP devices or the substrates [ 39 ].…”

“…Kim et al report a pin-type APPJ with the GB system for synthesizing a conducting polymer [ 63 ] and a transparent polymer [ 64 ]. As shown in Figure 4 c, this device consists of four components: a narrow glass for gas inlet, a wide glass tube as the guide tube, a polytetrafluoroethylene stand as the bluff body, and a tungsten wire electrode to generate plasma.…”

“… ( a ) Setup [ 59 ] and ( b ) photo image [ 62 ] of the APPJ with three array jets and a GB system. ( c ) Configuration [ 63 ] and ( d ) photo image [ 64 ] of the pin-type APPJ with a GB system. …”

Improvement of the Uniformity and Electrical Properties of Polyaniline Nanocomposite Film by Addition of Auxiliary Gases during Atmospheric Pressure Plasma Polymerization

“…Our research group has previously published details on the formation of polymer nanocomposite films using the AP plasma reactor [ 28 , 29 , 33 , 34 ]. The AP plasma polymerization process occurs in the space confined between the guide tube, which is connected to the plasma jet array, and the bluff body, which is the substrate stand.…”

“…The space enclosed by the guide tube and the substrate stand acts as a passive chamber for polymerization at AP. The guide tube with a 20-mm ID determines the plasma polymerization area, and the polytetrafluoroethylene substrate stand with a 15-mm diameter is also used as a bluff body, which disrupts the gas flow emerging from the APPJ array, allowing the discharge gas and various reactive products to remain inside the guide tube for a longer time [ 33 , 34 ]. To avoid the adverse effect of plasma generation by adding auxiliary gas, the auxiliary gas is directly added to the middle area of the guide tube through a separate gas line, as depicted in Figure 2 a.…”