A Close Look at Material Synthesis with Liquid Phase and Cryo Electron Microscopy [Invited]

Chemistry, and its manifestation as self-assembly, provides an elegant strategy to create functional, highly complex, and hybrid materials for a myriad of applications.¹ Through evolution, living systems, have achieved exquisite control over the deposition of both organic and inorganic building blocks to create hierarchical, composite materials with exceptional properties. This is achieved under ambient conditions by utilizing compartmentalization and confinement of chemical environments to control the pathway of formation, realizing structures and shapes that are not readily achievable in synthetic systems. If materials chemists are ever able to have this level of control, it will come from a deep understanding of general mechanisms and pathways that govern the self-assembly of hierarchical and hybrid structures in complex solution environments.²

Considering that materials synthesis in liquids, and deposition from liquids, pervades the vast majority of polymer science and soft matter research, imaging techniques that provide direct observations of structure and chemistry in solution with nanoscale resolution should be the leading analytical tools for driving self-assembly theory and experimental design. Techniques such as Liquid Phase Electron Microscopy (LPEM) and Cryogenic Electron Microscopy (CryoEM) provided an unprecedented insight into nanoscale reaction mechanisms, however their application is still extremely challenging. The primary challenge for the field of LP-EM is understanding the role that the electron beam plays in the observed mechanism. CryoEM is limited in its ability to resolve complex heterogeneous processes due to the inherent “freezing” of the samples which prevents knowledge of the future or history of any particle under inspection. Consequently, although LPEM and cryoEM enables us to take a close look at materials synthesis we are often left with the question, what does this mean? Our ability to overcome these challenges will be key in translating the insights from LPEM and cryoEM into new theories about the chemistry and self-assembly of materials and will ultimately dictate the future of these techniques for driving innovation in science and engineering.

References:

1. Whitesides, G. M.; Grzybowski, B., Self-assembly at all scales. Science 2002, 295 (5564), 2418-2421.
2. Patterson, J. P.; Xu, Y.; Moradi, M. A.; Sommerdijk, N.; Friedrich, H., CryoTEM as an Advanced Analytical Tool for Materials Chemists. Acc. Chem. Res. 2017, 50 (7), 1495-1501.