Nanomechanical characterisation of multilayered organic-inorganic composite films produced by bioinspired processing routes

该项目旨在通过既定的生物启发路线合成有机-无机复合薄膜的纳米力学研究。一个主要的目标是通过实施自然衍生的分子设计原则，赋予这些仿生分子结构优越的机械性能。所设想的复合薄膜应通过金属氧化物作为无机和带电聚合物作为有机组分的交替逐层组装在各种类型的表面改性衬底上制造。在项目的第一阶段，将选择通过低温化学浴沉积形成的二氧化钛层作为多层材料的无机成分，然后将研究扩展到由超高宽高比的氧化钒纳米纤维组成的层。对于后一种层的组装，将使用两种沉积方法，其中预先形成的纤维被吸附到表面上，或者纤维生长在适当的化学表面位置成核。为了研究复合膜的力学性能，应采用纳米压痕和纳米划痕试验，以确定硬度、杨氏模量、断裂韧性以及层与基体的粘附强度。为此目的，分析纳米压痕/纳米划痕数据的不同程序将根据其处理可能的复杂性（如表面粗糙度和基材的影响）的能力进行严格评估。在此基础上，多层结构的重要性将通过比较纳米压痕数据与从氧化物单层获得的数据作为参考来评估。进一步的测试，将进行广泛的结构表征，以实现多层形貌/组成与其机械性能之间的详细相关性。

This project aims at the nanomechanical investigation of organic-inorganic composite films synthesised via an established bioinspired route. A major goal is to impart superior mechanical properties on these biomimetic molecular architectures by the implementation of nature-derived molecular design principles. The envisioned composite films shall be fabricated on various types of surface-modified substrates through alternating layer-by-layer assembly of metal oxides as inorganic and charged polymers as organic components. While in the first stage of the project, titanium dioxide layers formed via low-temperature chemical bath deposition will be chosen as inorganic component of the multilayers, the investigations will then be extended to layers composed of vanadium oxide nanofibres with ultra-high aspect ratio. For the assembly of the latter type of layers, two deposition approaches will be used, in which either pre-formed fibres are adsorbed onto the surface, or the fibre growth is nucleated at suitable chemical surface sites. To investigate the mechanical properties of the composite films, nanoindentation and nanoscratch tests shall be employed, in order to determine hardness, Young s modulus, fracture toughness as well as the adhesion strength of the layers to the substrate. For this purpose, different procedures for analysing the nanoindentation/nanoscratch data will be critically evaluated with respect to their ability to cope with possible complications such as surface roughness and the influence of the substrate. On that basis, the importance of the multilayered architecture will be evaluated by comparing the nanoindenation data with those obtained from oxide monolayers as reference. Further to this testing, extensive structural characterisations will be made to enable a detailed correlation between the multilayer morphology/composition and their mechanical performance.