Seeing how polymer chains organise with torsional tapping atomic force microscopy

我们对半结晶聚合物的理解是令人惊讶的，这类聚合物在现代社会中占据主导地位。在分子尺度上，我们依赖于漫画和推理，无法达到材料科学其他领域通过直接，原子或分子尺度成像以及宏观晶体衍射获得的确定性。然而，在聚合物中，该水平的结构可以说是更重要的，因为它决定了从机械行为到氧气阻隔性能，通过粘合行为到美学吸引力的性能。最近，我们开发了一种新形式的原子力显微镜，扭转轻敲AFM（TTAFM）能够鲁棒和常规获得图像与真正的分子分辨率上最常用的聚合物（聚烯烃，包括聚乙烯和聚丙烯）在基本上任何样品。性能的这种阶跃变化是基于悬臂几何形状和驱动机制带来的改进的动态和信噪比性能。预计完善悬臂梁设计将带来更高的性能，并允许该技术在广泛的仪器中使用。在开发这项技术的同时，我们将用它来回答一系列问题，这些问题巩固了我们对聚合物晶体的理解，这些问题将大大增强对聚合物晶体的基本理解和真实的应用，从开发新材料和应用到解决加工过程中的问题。我们的目标是直接揭示结晶温度、链化学变化、链支化、增强纤维和颗粒如何控制晶体内以及晶体与非结晶材料之间界面处的聚合物链的组织。在这样做的同时，我们将完善分子尺度成像的样品制备方法，并增强悬臂梁设计以提高性能，使该技术在聚合物科学和分子纳米科学中得到广泛采用。

Our understanding of semicrystalline polymers, the class of polymers that by far and away dominates usage in modern society, is surprisingly poor. At a molecular scale we rely on cartoons and inference, unable to reach the certainty obtained in other areas of material science by direct, atomic or molecular scale imaging, and by diffraction from macroscopic crystals. Yet in polymers the structure at this level is arguably more important as it determines the properties from mechanical behaviour to the oxygen barrier performance through the adhesive behaviour to the aesthetic appeal. Recently we developed a new form of atomic force microscopy, torsional tapping AFM (TTAFM) capable of robustly and routinely obtaining images with true molecular resolution on the most frequently used polymers (polyolefins, that include polyethylene and polypropylene) in essentially any sample. This step change in performance is based on the improved dynamics and signal-to-noise performance that comes from the cantilever geometry and drive mechanism. Perfecting the cantilever design is predicted to lead to even greater performance, and to allow the technique to be used in a wide range of instruments. At the same time as developing the technology we will use it to answer a string of questions that underpin our understanding of polymer crystals, questions that will lead to both greatly enhanced fundamental understanding and real application from the development of new materials and applications to problem solving during processing. We aim to directly reveal how crystallization temperature, variations in chain chemistry, chain branching, re-enforcing fibres and particles, control the organisation of polymer chains within the crystal and at the interface between the crystal and the non-crystalline material. While doing this we will perfect the sample preparation methods for molecular scale imaging, and enhance the cantilever design to improve performance, allowing the technique to be widely adopted both in polymer science and across molecular nanoscience.