Faculté des Sciences, Service de Chimie Analytique et Chimie des Interfaces, Université Libre de Bruxelles, CP-255, Bld du Triomphe 2, B-1050 Bruxelles, Belgium.
Langmuir. 2012 Jun 26;28(25):9466-74. doi: 10.1021/la300822j. Epub 2012 Jun 4.
A comparative study of polytetrafluoroethylene (PTFE) surfaces treated by the post-discharge of He and He-O(2) plasmas at atmospheric pressure is presented. The characterization of treated PTFE surfaces and the species involved in the surface modification are related. In pure He plasmas, no significant change of the surface has been observed by X-ray photoelectron spectroscopy (XPS), dynamic water contact angles (dWCA) and atomic force microscopy (AFM), in spite of important mass losses recorded. According to these observations, a layer-by-layer physical etching without any preferential orientation is proposed, where the highly energetic helium metastables are the main species responsible for the scission of -(CF(2))(n)- chains. In He-O(2) plasmas, as the density of helium metastables decreases as a function of the oxygen flow rate, the treatment leads to fewer species ejected from the PTFE surfaces (in agreement with mass loss measurements and the detection of fluorinated species onto aluminum foil). However, the dWCA and AFM measurements show an increase in the hydrophobicity and the roughness of the surface. The observed alveolar structures are assumed to be caused by an anisotropic etching where the oxygen atoms etch mainly the amorphous phase.
本研究对比了大气压下 He 和 He-O(2)等离子体后放电处理的聚四氟乙烯（PTFE）表面。文中阐述了处理过的 PTFE 表面的特性以及涉及的表面改性的物质。在纯 He 等离子体中，尽管记录到了大量的质量损失，但 X 射线光电子能谱（XPS）、动态水接触角（dWCA）和原子力显微镜（AFM）均未观察到表面有明显变化。根据这些观察结果，提出了一种无任何优先取向的逐层物理蚀刻，其中高能氦亚稳态是导致 -(CF(2))(n)- 链断裂的主要物质。在 He-O(2)等离子体中，随着氧流速的增加，氦亚稳态的密度降低，从 PTFE 表面喷射出的物质也减少（与质量损失测量和铝箔上氟化物质的检测结果一致）。然而，dWCA 和 AFM 测量表明表面的疏水性和粗糙度增加。观察到的肺泡结构被认为是各向异性蚀刻的结果，其中氧原子主要蚀刻无定形相。
