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Aiming to get a better understanding of the growth mechanism during the plasma polymerization process of ethyl lactate, the surface reactivity of ester-bearing fragments has been determined by combining in situ FTIR spectroscopy and XPS measurements. While the plasma density of the reactive ester-bearing fragment decreases by one order of magnitude (from ~2x1020m-3 to ~2x1019m-3) as the power increases from 60 to 280 W, the ester group density in the plasma polymer films decreases from ~1.5x1019m-2/m² to ~1.7x1017m². The associated incorporation efficiency of the reactive ester-bearings fragments in the films (sester) consequently increases from 2.6x10-6 to 1.3x10-4 when increasing the power. This behavior is attributed to higher activation the growing film surface. [ABSTRACT FROM AUTHOR]

Plasma polymer films are more and more used in numerous applications such as the day-to-day packaging, which requires a good mechanical resistance of the coating. Since mechanical properties are function of the cross-linking degree of the thin films, it is important to understand the relationship between the two. In this work, plasma polymer films were studied in terms of cross-linking degree and mechanical properties, measured by means of ToF-SIMS coupled to PCA and depth-sensing nanoindentation, respectively. The data reveal that when the power increases, the films are more cross-linked and show higher hardness, higher elastic recovery, lower creep strain and an increased ability for self-healing. As the plasma polymer films are more cross-linked, the plasticity drops and the viscoelasticity and hardness increase. [ABSTRACT FROM AUTHOR]

In this work, a new plasma diagnostic method has been used to quantify the plasma-generated species that play a part in the ethyl lactate plasma polymer film deposition. This method has been possible by using the RGA mass spectrometry combined with the in situ FTIR spectroscopy supported by DFT calculations. Ethyl lactate plasma phase can then be qualitatively and quantitatively probed by varying the experimental parameters. More specifically, it has been shown that by increasing the power from 30 to 280 W, the density of ester-bearing species in the plasma strongly decreases and supports the drop of ester content in plasma polymers. Additionally, the temperature of the plasma has been determined by the in situ IR spectroscopy and has revealed a too weak increase (60 K) to affect the fundamental vibrational levels. Our IR spectroscopy approach goes into that direction too. [ABSTRACT FROM AUTHOR]