Exploiting Reactor Geometry to Manipulate the Properties of Plasma Polymerized Acrylic Acid Films.

Karyn Jarvis,Sally Mcarthur

doi:10.3390/ma12162597

Karyn Jarvis, Sally Mcarthur

Open Access

https://doi.org/10.3390/ma12162597

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Journal: Materials	Publication Date: Aug 15, 2019
Citations: 10	License type: CC BY 4.0

Affiliation: Swinburne University of Technology, CSIRO Manufacturing

Abstract

A number of different reactor geometries can be used to deposit plasma polymer films containing specific functional groups and result in films with differing properties. Plasma polymerization was carried out in a low-pressure custom-built stainless steel T-shaped reactor using a radio frequency generator. The internal aluminium disk electrode was positioned in two different geometries: parallel and perpendicular to the samples at varying distances to demonstrate the effect of varying the electrode position and distance from the electrode on the properties of plasma polymerized acrylic acid (ppAAc) films. The surface chemistry and film thickness before and after aqueous immersion were analysed via X-ray photoelectron spectroscopy and spectroscopic ellipsometry, respectively. For a perpendicular electrode, the ppAAc film thicknesses and aqueous stability decreased while the COOH/R group concentrations increased as the distance from the electrode increased due to decreased fragmentation. For films deposited at similar distances from the electrode, those deposited with the parallel electrode were thicker, had lower COOH/R group concentrations and greater aqueous stability. These results demonstrate the necessity of having a well characterized plasma reactor to enable the deposition of films with specific properties and how reactor geometry can be exploited to tailor film properties.

Highlights

Plasma polymerization modifies surfaces via the deposition of a thin film containing specific functional groups
Reactor geometry has shown to have a significant effect on the thickness, COOH/R group
Reactor geometry has shown to have a significant effect on the thickness, COOH/R group concentrations and aqueous stability of plasma polymerized acrylic acid (ppAAc) films, and can, be utilized to produce films concentrations and aqueous stability of ppAAc films, and can, be utilized to produce films with tailored properties

Summary

Introduction

Plasma polymerization modifies surfaces via the deposition of a thin film containing specific functional groups. The properties of plasma polymer films, such as chemistry, thickness and stability are conventionally controlled by varying the input monomer/gas, plasma power, monomer flow rate and deposition time. Deposition at lower powers reduces monomer fragmentation, which results in the deposition of relatively intact monomer molecules on the surface; these films tend to be less stable in solution due to their low crosslinking [2] and incorporation of low-molecular-weight fragments within the film [3,4,5]. Increasing the power tends to produce more stable films due to higher crosslinking; the number of functional groups are typically reduced due to greater monomer fragmentation [6]. The properties of plasma polymerized acrylic acid (ppAAc) can be influenced by other parameters such as co-polymerization [7,8,9,10,11,12], plasma pulsing [13,14,15,16,17,18] and reactor geometry [3,19,20,21]

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