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The effect of the composite plasma parameter P/F, where P is the plasma power and F is the monomer flow rate, on the chemical character of pulsed plasma deposited allyl alcohol films was investigated by ToF-SSIMS. Information on the unsaturated character, the cross-linked and/or branched character of the plasma polymer films was derived in detail. The problem of the retention of OH groups in plasma deposited allyl alcohol films was elucidated in detail using SSIMS data. The lowest conversion rate from the monomer's hydroxyl groups to other oxygen functionalities in the plasma was concluded for the plasma polymer film produced at a P/F ratio of 0.05 W · sccm-1. It was found that the overall oxygen content of the films decreased vs. increasing P/F ratio. Because the freshly prepared films were investigated without air exposure, ageing on ambient air could be studied in detail. It was found that in the case of plasma deposited allyl alcohol films the ageing on air is probably based on two competing processes which are discussed in detail. Additionally, a review of literature data on the characterization of plasma deposited allyl alcohol films is given.
Pulsed-plasma-deposited ethylene films were studied by time-of-flight static secondary ion mass spectrometry (ToF-SSIMS) before and after exposure to ambient air. The influence of the external plasma parameters on the secondary ion mass spectra of plasma-deposited ethylene films was investigated. From these data, information on the chemical character of the plasma-deposited ethylene films was derived. The investigation of the effect of external plasma parameters on the chemical character of the plasma-deposited ethylene films revealed that there were some drastic changes in the secondary ion mass spectra of the films. It was found that fragmentation and re-arrangement of the monomer molecules in the plasma, which affects the chemical character of the deposited films, vary according to the external plasma parameters. When the plasma polymers are exposed to air, extensive oxygen incorporation occurs. The oxygen uptake is high at the beginning and then it levels of. Some indications for the formation and decay of peroxy radicals (COO) and, subsequently, hydroperoxides (COOH) are found. It was observed that the oxygen uptake of the plasma deposited ethylene films increase when the plasma conditions become harder.
Pulsed plasma deposited styrene and ethylene films were studied by Time of Flight Static Secondary Ion Mass Spectrometry (ToF-SSIMS) before and after exposure to ambient air. The influence of the external plasma parameters on the secondary ion mass spectra of plasma deposited films was investigated. Approaches for the interpretation of SSIMS spectra of organic materials were reviewed and applied to the evaluation of SSIMS data of plasma deposited films. From these data, information on the chemical character of the plasma deposited films was derived.
When the plasma polymers are exposed to air oxygen incorporation occurs. The oxygen uptake is high at the beginning and then it levels of.
A relation that higher the regularity of the film lower is the oxygen uptake was found. Harder plasma conditions, which could be obtained by applying higher plasma power or lower monomer flow rate, result in higher oxygen uptake and vice versa.
Nitrogen rich plasma polymer films (L-PPE:N) were prepared by low-pressure RF plasma using a 1:1 mixture of ethylene and ammonia and aged for 345 d in four different ambient conditions: (i) at room temperature (RT) in air; (ii) at RT in nitrogen; (iii) at -20?°C in air and; (iv) at –20 °C in nitrogen. The films were analyzed by X-ray photoelectron spectroscopy (XPS) and by time-of-flight secondary ion mass spectrometry (ToF-SIMS) at various intervals over the duration of the experiment. The ageing of primary amines, NH2, was followed by chemical derivatization with 4-trifluoromethyl benzaldehyde. Storage at –20 °C, mostly independently of ambient atmosphere, slowed down ageing to almost undetectable levels as evaluated by the analytical methods used for this study.