Octiv Mono Publications

Plasma Parameter Aspects in the Fabrication of Stable Amine Functionalized Plasma Polymer Films

Carla Daunton, Louise E. Smith, Jason D. Whittle, Robert D. Short, David A. Steele and Andrew Michelmore

Published 12th February 2015

Abstract

Amine containing plasma polymer films are of interest due to their ability to bind biomolecules either covalently or electrostatically. One issue with generating such plasma polymers is the need to generate sufficient amine density on the surface to enable binding, while simultaneously maintaining the chemical, physical stability of the surface in aqueous media. Here we investigate the relationship between plasma parameters, film stability for two commonly used monomers, allylamine AA, ethylenediamine EDA. Plasma polymer films from AA, EDA were produced at radio frequency RF powers between 2 and 20 W at a constant monomer flowrate. Deposition rate, ion flux, ion energy, plasma phase mass spectrometry were used to investigate the plasma-surface interactions. Film stability was assessed by comparing X-ray photoelectron spectroscopy XPS, atomic force microscopy AFM measurements before, after washing in phosphate buffered saline PBS. The results show that films generated from EDA plasmas are generally unstable in aqueous media, while films generated from AA plasmas exhibit higher stability, particularly those deposited at high RF power. The chemical, physical stability of the films is then related to the mechanisms of deposition, the energy density provided to the surface during film growth.

Online at Plasma Process. Polym. 2015, 12, 817–826 DOI: 10.1002/ppap.201400215


An Experimental and Analytical Study of an Asymmetric Capacitively Coupled Plasma Used for Plasma Polymerization

Andrew Michelmore, Jason D. Whittle, Robert D. Short, Rod W. Boswell, Christine Charles

Published 4th June 2014

Abstract

Plasma processing is widely used to provide novel surface modifications to materials for a variety of
applications. Typically, the systems used to carry out these modifications are poorly characterised. Here we describe the basics of a global model for a capacitively coupled asymmetric parallel plate radiofrequency plasma system routinely used to produce plasma polymers. An analytical global model was developed for argon, for which cross-sections are known, at a constant pressure of 1 Pa, and includes an electrical model and a power balance. The main parameters of interest were ion flux and self-bias voltages. The argon modelling results were then compared to experimental results for a range of operating gases (argon, oxygen, amines, acids, alcohols, ethers, siloxanes) including both saturated and unsaturated compounds with molecular weights ranging from 40 to 162 g mol1, for different inter-electrode separations and from 2 to 50 W using an Impedans OctIV probe. Importantly, it is shown that the RF power transfer efficiency is dependent on the gas. The results show that the argon model results can be used to predict the plasma parameters for other gases when the RF power transfer efficiency is taken into account.

Online at Plasma Process. Polym. 2014, 11, 833–841 DOI: 10.1002/ppap.201400026