Plasma polymerization experiments are typically conducted by sustaining a non-thermal plasma in a gas flow containing monomer molecules. Recently, it was however observed that plasma polymerization can also occur in a nitrogen/2% ethanol vapor dielectric barrier discharge operated at medium pressure (5.0 kPa). To obtain a better understanding of this peculiar plasma polymerization behavior, a detailed parameter study is conducted in this work. The influence of plasma exposure time at fixed discharge power on the coating properties is investigated as well as the influence of discharge power applying a fixed energy density. Results reveal that at a discharge power ≥ 3.0 W, very hydrophilic (WCA values < 11°) coatings are deposited possessing N/C ratios in the range 32–38% and O/C ratios in the range 21–40%. XPS analysis shows that the coatings mainly consist out of amides, amines, imines and nitril/isonitrile groups. FTIR results confirm this conclusion and also show that the C≡N groups are mainly present as isonitriles. With increasing discharge power, a small decrease in O/C ratio is observed combined with an increasing amount of isonitriles. The investigated treatment times also do not affect the surface chemical composition nor the surface wettability suggesting excellent in-depth coating homogeneity. The plasma exposure time does however strongly affect the coating thickness: a linear increase in coating thickness with plasma exposure time is observed in this work. The obtained results thus prove that a nitrogen/ethanol vapor DBD operated at medium pressure is capable of depositing highly hydrophilic nitrogen- and oxygen-rich deposits, which can have applications in different research areas.

中文翻译：

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氮/乙醇介质阻挡放电中的等离子体聚合：参数研究

等离子体聚合实验通常通过在含有单体分子的气流中维持非热等离子体来进行。然而，最近观察到，在中等压力 (5.0 kPa) 下操作的氮气/2% 乙醇蒸汽介质阻挡放电中也可以发生等离子体聚合。为了更好地了解这种特殊的等离子体聚合行为，在这项工作中进行了详细的参数研究。研究了固定放电功率下等离子体暴露时间对涂层性能的影响以及施加固定能量密度的放电功率的影响。结果表明，在放电功率 ≥ 3.0 W 时，沉积的非常亲水（WCA 值 < 11°）涂层的 N/C 比在 32-38% 范围内，O/C 比在 21-40% 范围内。XPS 分析表明涂层主要由酰胺、胺、亚胺和腈/异腈基团组成。FTIR 结果证实了这一结论，并且还表明 C≡N 基团主要以异腈的形式存在。随着放电功率的增加，观察到 O/C 比的小幅下降以及异腈含量的增加。研究的处理时间也不影响表面化学成分，也不影响表面润湿性，表明深度涂层的均匀性非常好。然而，等离子体暴露时间确实强烈影响涂层厚度：在这项工作中观察到涂层厚度随等离子体暴露时间线性增加。因此，所得结果证明在中压下操作的氮/乙醇蒸汽 DBD 能够沉积高度亲水的富氮和富氧沉积物，