"Cinematography" of soft, biological and energy matter at the nanoscale.
I will discuss my group’s recent progress on adapting a suite of electron microscopy methods including low-dose liquid-phase TEM, electron tomography and scanning electron nanodiffraction (SEND) to synthetic soft, biological and energy related systems. The first vignette focuses on capturing and understanding the fluctuation dynamics at the nanometer resolution using liquid-phase TEM. The specific systems concern the nucleation and growth pathways of nanoparticles into superlattices and membrane proteins in their native lipid and liquid environment. Single particle tracking, machine learning and simulations combined unravel the energetic and kinetic characteristics generic to the unexplored nanoscale, enabling advanced crystal engineering. For membrane proteins, we find that they exhibit real-time “fingering” fluctuations, which we attribute to dynamic rearrangement of lipid molecules wrapping the proteins. The conformational coordinates of protein transformation obtained from the real-space movies are used as inputs in our molecular dynamics simulations, to verify the driving force underpinning the function-relevant fluctuation dynamics. The second vignette focuses on the “morphogenesis” of synthetic materials as revealed by electron tomography in 3D at the nanometer resolution, to shift the current paradigm of relating synthesis/processing to performance, to establishing a synthesis/processing–morphology–performance relationship, especially in the synthesis of polyamide membranes for water purification and patchy nanoparticles. The third vignette concerns the strain engineering in cathode materials for grid scale energy storage. By collaborating with the Zuo group, for the first time we are able to achieve concurrent imaging of chemical phases and strains at an unprecedented nanometer resolution by SEND, which elucidates an intriguing chemomechanical coupling with nanoscale heterogeneity encoded by solvent and charge rate of the systems. We foresee our suite of “cinematography” tools to provide crucial and complementary insights in various materials systems, with the common theme of probing the elusive nanoscale.
