Investigation of the formability of thin nanoclay containing polyelectrolyte films on NiTi-substrates in humid environments

为了了解纳米粘土/聚电解质薄膜在金属衬底上的可成形性，我们将聚电解质层的逐层生长与脱落的纳米粘土的吸附结合起来，在NiTi单晶衬底上沉积具有特定化学性质的纳米复合薄膜。选择镍钛是因为它的假弹性特性和在生物医学应用中抑制金属释放的需要。选择LBL聚电解质薄膜是因为它具有明确的静电分子间作用力和静电相互作用在热固化过程中可能转化为共价键，并因此具有特殊的粘弹性。氧化物覆盖的镍钛合金与薄复合膜之间的界面将通过双功能有机膦酸的自组装来定制。薄膜的结构和化学成分将通过光谱学和显微技术进行分析。每个科学小组将进行特殊的互补原位测量，如原位电子显微镜和原位电化学阻抗谱，以研究成形过程中和成形过程后的成形行为和缺陷形成。因此，纳米复合薄膜的可成形性和自修复性能与薄膜内部（聚电解质之间和聚电解质与纳米粘土之间）的界面力、薄膜与衬底之间的界面力以及薄膜的形貌直接相关。此外，还将研究掺入水对界面力和粘弹性的变化对成形性的影响。

For the understanding of the formability of thin nanoclay/polyelectrolyte films on metal substrates, layer-by-layer growth of polyelectrolyte layers in combination with the adsorption of exfoliated nanoclay is performed to deposit nanocomposite films of defined chemistry onto NiTi single crystal substrates. NiTi is chosen due to its pseudoelastic properties and the need to inhibit metal release in case of a biomedical application of this shape memory alloy. LBL polyelectrolyte films are chosen because of the defined electrostatic intermolecular forces and the possible conversion of electrostatic interactions to covalent bonds by thermal curing and the thereby special viscoelastic properties. The interface between the oxide covered NiTi-alloy and the thin composite film will be tailored by the self-assembly of bi-functional organophosphonic acids. The structure and chemical composition of the thin films will be analysed by spectroscopic and microscopic techniques. Each scientific group will perform special complementary in-situ measurements such as in-situ electron microscopy and in-situ electrochemical impedance spectroscopy to study the forming behaviour and the defect formation during and directly after the forming process. Thereby, the formability and selfrepair properties of the thin nanocomposite films can be directly correlated with the interfacial forces within the film (between the polyelectrolytes and between polyelectrolytes and the nanoclay), the interfacial forces between the film and the substrate and the morphology of the thin film. Moreover, the influence of the change in interfacial forces and the viscoelastic properties by incorporated water on the formability will be studied.