title: Liquid Cell Electron Microscopy of Nanoparticle Self-Assembly Driven by Solvent Drying.
abstract: Drying a colloidal solution of nanoparticles is a versatile method to construct self-assembled structures of nanoparticles. However, mechanistic understanding has mostly relied on empirical knowledge obtained from the final structures of self-assembly as relevant processes during solvent drying are likely kinetic and far from equilibrium. Here, we present in situ TEM studies of nanoparticle self-assembly under various conditions, including the concentrations of the initial solution and the types of nanoparticles and substrates. The capability of tracking trajectories of individual nanoparticles enables us to understand the mechanisms of drying-mediated self-assembly at the single-nanoparticle level. Our results consistently show that a solvent boundary primarily affects nanoparticle motions and the resulting self-assembly processes regardless of different conditions. The solvent boundary drives nanoparticles to form two-dimensional assembly mainly through two pathways, transporting scattered nanoparticles by lateral dragging and flattening aggregated nanoparticles by vertical pressing.
authors.affiliation: Department of Mechanical Engineering, Hanyang University , Ansan, Gyeonggi 15588, Republic of Korea.|Institute of Industrial Science, The University of Tokyo , Tokyo 153-8505, Japan.|ERATO Takeuchi Biohybrid Innovation Project, Japan Science and Technology Agency , Tokyo 153-8904, Japan.
authors.forename: Won Chul
authors.identifier: http://orcid.org/0000-0001-8479-0836
authors.initials: WC
authors.lastname: Lee
authors.affiliation: Center for Nanoparticle Research, Institute for Basic Science (IBS) , Seoul 08826, Republic of Korea.|School of Chemical and Biological Engineering, Seoul National University , Seoul 08826, Republic of Korea.
authors.forename: Byung Hyo
authors.initials: BH
authors.lastname: Kim
authors.affiliation: Center for Urban Energy Research, Korea Institutes of Science and Technology , Seoul 02792, Republic of Korea.
authors.forename: Sun
authors.initials: S
authors.lastname: Choi
authors.affiliation: Institute of Industrial Science, The University of Tokyo , Tokyo 153-8505, Japan.|ERATO Takeuchi Biohybrid Innovation Project, Japan Science and Technology Agency , Tokyo 153-8904, Japan.
authors.forename: Shoji
authors.identifier: http://orcid.org/0000-0001-6946-0409
authors.initials: S
authors.lastname: Takeuchi
authors.affiliation: Center for Nanoparticle Research, Institute for Basic Science (IBS) , Seoul 08826, Republic of Korea.|School of Chemical and Biological Engineering, Seoul National University , Seoul 08826, Republic of Korea.
authors.forename: Jungwon
authors.identifier: http://orcid.org/0000-0003-2927-4331
authors.initials: J
authors.lastname: Park