Parent Lucas R, Gnanasekaran Karthikeyan, Korpanty Joanna, Gianneschi Nathan C
Innovation Partnership Building, The University of Connecticut, Storrs, Connecticut 06269, United States.
ACS Macro Lett. 2021 Jan 19;10(1):14-38. doi: 10.1021/acsmacrolett.0c00595. Epub 2020 Dec 8.
A century ago, Hermann Staudinger proposed the macromolecular theory of polymers, and now, as we enter the second century of polymer science, we face a different set of opportunities and challenges for the development of functional soft matter. Indeed, many fundamental questions remain open, relating to physical structures and mechanisms of phase transformations at the molecular and nanoscale. In this Viewpoint, we describe efforts to develop a dynamic, microscopy tool suited to the study of polymeric materials at the nanoscale that allows for direct observation of discrete structures and processes in solution, as a complement to light, neutron, and X-ray scattering methods. Liquid-phase transmission electron microscopy (LPTEM) is a nascent imaging technique for characterizing and examining solvated nanomaterials in real time. Though still under development, LPTEM has been shown to be capable of several modes of imaging: (1) imaging static solvated materials analogous to cryo-TEM, (2) videography of nanomaterials in motion, (3) observing solutions or nanomaterials undergoing physical and chemical transformations, including synthesis, assembly, and phase transitions, and (4) observing electron beam-induced chemical-materials processes. Herein, we describe opportunities and limitations of LPTEM for polymer science. We review the basic experimental platform of LPTEM and describe the origin of electron beam effects that go hand in hand with the imaging process. These electron beam effects cause perturbation and damage to the sample and solvent that can manifest as artefacts in images and videos. We describe sample-specific experimental guidelines and outline approaches to mitigate, characterize, and quantify beam damaging effects. Altogether, we seek to provide an overview of this nascent field in the context of its potential to contribute to the advancement of polymer science.
一个世纪前，赫尔曼·施陶丁格提出了聚合物的大分子理论。如今，当我们进入聚合物科学的第二个世纪时，功能性软物质的发展面临着一系列不同的机遇和挑战。事实上，许多基本问题仍然悬而未决，这些问题涉及分子和纳米尺度上的物理结构及相变机制。在这篇观点文章中，我们描述了开发一种动态显微镜工具的努力，该工具适用于在纳米尺度上研究聚合物材料，能够直接观察溶液中的离散结构和过程，作为对光散射、中子散射和X射线散射方法的补充。液相透射电子显微镜（LPTEM）是一种用于实时表征和检测溶剂化纳米材料的新兴成像技术。尽管仍在发展中，但LPTEM已被证明能够实现多种成像模式：（1）对类似于冷冻透射电子显微镜的静态溶剂化材料进行成像；（2）对运动中的纳米材料进行摄像；（3）观察正在经历物理和化学转变（包括合成、组装和相变）的溶液或纳米材料；（4）观察电子束诱导的化学-材料过程。在此，我们描述了LPTEM在聚合物科学中的机遇和局限性。我们回顾了LPTEM的基本实验平台，并描述了与成像过程相伴的电子束效应的起源。这些电子束效应会对样品和溶剂造成扰动和损伤，可能在图像和视频中表现为伪像。我们描述了针对特定样品的实验指南，并概述了减轻、表征和量化束损伤效应的方法。总之，我们试图在这个新兴领域对聚合物科学进步的潜在贡献的背景下，对其进行概述。
