Chemical Characterization of the Long-Term Ageing of Nitrogen-Rich Plasma Polymer Films under Various Ambient Conditions

摘要

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℃ in air and; (iv) at -20℃ 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, NH_2, was followed by chemical derivatization with 4-trifluoro-methyl benzaldehyde. Storage at -20℃, mostly independently of ambient atmosphere, slowed down ageing to almost undetectable levels as evaluated by the analytical methods used for this study.