Fundamental investigations of interlayer processes occurring during DLC coating of selected plastics

如今，塑料材料由于其优越的性能（弹性和低重量）而可以在许多应用领域中找到。然而，它们的一些不利特性（低硬度和耐磨强度、微生物粘附）大大限制了它们在某些应用领域（例如医学）中的使用。用类金刚石碳（DLC）涂层可以改善传统塑料材料的性能，从而扩大其应用范围。一般来说，DLC层被认为是坚固的、抗菌的和生物相容的保护层。虽然DLC层可以涂覆在大量材料上，但DLC涂层塑料的研究还很少。特别是在初始涂层过程中原始表面的化学和物理性质的变化还完全不清楚。本研究项目的目的是阐明和定义在选定的塑料（聚乙烯，聚甲醛）表面上等离子体辅助沉积DLC层期间发生的过程。研究工作将特别侧重于详细解释层生长过程中的初始过程以及软塑性材料和硬质DLC之间边界层的相应修改。主要的反应过程将被分配到可能的过程类型，如沉积，夹层形成和侵蚀。只有很少的原子层沉积，以分析新兴的边界层。在涂覆过程中，借助高分辨率质谱仪连续观察反应室中组分的组成。这有助于澄清哪些等离子体相互作用发生与基板和多远，这可以通过改变工艺parameters.We期望获得有关的结合性能的DLC层和基板之间的边界层使用各种X-射线光谱方法（XPS，NEXAFS）的相关信息的影响。此外，除了涂层参数外，化学成分和基体表面以及沉积DLC的量也会对涂层塑料材料的结合（边界层）和形态产生影响。本项目的目的是对硬（DLC）和软（塑料）材料之间的结合有一个基本的了解。使用的塑料材料作为典型的模型基板。研究结果将被转移到其他聚合物材料中，从而能够生产具有改变的表面特性的替代材料，例如低磨损行为，同时在未来具有柔性和生物相容性表面。

Nowadays plastic material can be found in many fields of application due to their advantageous properties (elasticity and low weight). However, some of their disadvantageous characters (low hardness and abrasion strength, microbial adhesion) limit their use considerably in some fields of application (e.g. medicine). Properties can be improved and consequently applications of conventional plastic material can be extended by coating them with diamond-like carbon (DLC). Generally DLC layers are considered to be robust, anti-bacterial and bio-compatible protective layers. Although DLC layers can be coated on a high number of materials, DLC-coated plastics are yet sparsely investigated. Especially the changes of the chemical and physical properties of the original surface during the initial coating process are yet thoroughly unclear.The purpose of this research project is to elucidate and define the processes that take place during the plasma-assisted deposition of DLC layers on the surface of chosen plastics (polyethylene, polyoxymethylene). Research work will especially focus on the detailed explanation of the initial process during the growing of the layers and the accompanying modifications on the boundary layer between soft plastic material and hard DLC. The prevalent reaction processes will be assigned to the possible process types like deposition, interlayer formation and erosion.Only very few atomic layers are deposited in order to analyze the emerging boundary layer. The composition of the components in the reaction chamber is being observed continuously during the coating process with the help of high-resolution mass spectroscopy. This serves to clarify which plasma interaction takes place with the substrate and how far this can be influenced by varying the process parameters.We expect to obtain relevant information concerning the binding properties on the boundary layer between the DLC layer and the substrate using various x-ray spectroscopy methods (XPS, NEXAFS). Furthermore it is assumed that apart from the coating parameters also chemical composition and the surface of the substrate as well as the amount of deposited DLC have influence on the resulting bonding (boundary layer) and the resulting morphology of the coated plastic material.The purpose of this project is to achieve a basic understanding of the bonding between hard (DLC) and soft (plastic) materials. The used plastic materials serve as typical model substrates. The results will be transferred to other polymer materials thus enabling the production of alternative materials with changed surface characteristics such as low abrasive behavior and at the same time flexible as well as biocompatible surfaces in the future.