Mobility of Single Molecules at the Interfaces of Thin Polymer Films

结合纳米技术和聚合物是一个非常令人兴奋的，跨学科的研究领域，在自然科学和工程。在这里，创建的界面的过程和结构显着不同，从以前已知的散装。通过在这个项目中直接观察单分子的更深层次的可能性，我们期望对这些界面的动态有新的见解，从中可以产生有助于解决我们现代世界挑战的创新。特别是，流动性的详细了解是必不可少的聚合物材料的纳米技术应用，界面越来越占主导地位的材料的性能与日益微型化。界面处的动力学对于电子元件、有机发光二极管、太阳能电池或选择性分离系统和膜等具有极大的相关性，并且还决定了它们的长期稳定性。尽管广泛的研究，在界面处的聚合物动力学和聚合物性质的变化仍然没有完全理解。其中一个原因是聚合物不同区域行为的各个方法的平均值不同。为了避免这一点，在单分子水平上观察聚合物动力学是必要的。在这个项目中，我们专注于界面（空气或基板）附近的聚合物薄膜中的分子的流动性。利用现代单分子荧光方法，我们观察到单个探针分子在聚合物界面的平移和旋转运动。与早期的研究相比，我们现在可以通过实验实现所需的空间纳米分辨率，特别是垂直于界面。这种轴向分辨率可以通过最近开发的金属诱导能量转移（MIET）成像来实现，我们将联合收割机与单分子定位显微镜和散焦宽场显微镜在该项目中使用一种新型的单分子灵敏宽场荧光寿命探测器。因此，单分子的平移和旋转运动可以与它们的位置相关，具有前所未有的各向同性3D分辨率。因此，我们将研究荧光探针在聚合物膜界面的平移和旋转运动的温度依赖性，并阐明在不同聚合物界面处迁移率是否以及以何种z分布变化。因此，我们的项目代表了从系综测量过渡的重要一步，系综测量在膜中的整个动力学上平均，局部动力学的观察，并将决定性地扩大在纳米范围内的界面附近的（大）分子的流动性的理解。

Combining nanotechnology and polymers is an extremely exciting, interdisciplinary field of research in the natural sciences and engineering. Here, interfaces are created at which processes and structures differ significantly from what was previously known from bulk. Through deeper possibilities of direct single-molecule observation in this project, we expect new insights into the dynamics at such interfaces, from which innovations that contribute to solutions to the challenges of our modern world can arise. In particular, a detailed understanding of mobility is essential for nanotechnological applications of polymeric materials, as interfaces increasingly dominate the properties of materials with increasing miniaturization. The dynamics at interfaces is of utmost relevance for electronic components, organic light-emitting diodes, solar cells or selective separation systems and membranes, among others, and also determines their long-term stability. Despite extensive research, the changes in polymer dynamics and polymer properties at interfaces are still not fully understood. One of the reasons for this is the different averaging of individual methods over the behavior of different areas of the polymer. To circumvent this, the observation of polymer dynamics at the single molecule level is necessarily required. In this project, we focus on the mobility of molecules in polymer films near an interface (air or substrate). Using modern single-molecule fluorescence methods, we observe the translational and rotational motion of single probe molecules at polymer interfaces. In contrast to earlier studies, we can now experimentally achieve the required spatial nanometer resolution, especially perpendicular to the interface. This axial resolution can be achieved by recently developed metal-induced energy transfer (MIET) imaging, which we will combine with single-molecule localization microscopy and defocused wide-field microscopy in the project using a novel, single-molecule sensitive wide-field fluorescence lifetime detector. Thus, translational and rotational motion of single molecules can be correlated with their position with unprecedented isotropic 3D resolution. Thus, we will investigate the temperature dependence of the translational and rotational motion of fluorescent probes at the interfaces of polymer films and elucidate whether and with which z-profile the mobility changes at different polymer interfaces.Our project thus represents an essential step in the transition from ensemble measurements, which average over the entire dynamics in a film, to the observation of local dynamics and will decisively expand the understanding of the mobility of (macro)molecules in the vicinity of interfaces in the nanometer range.