高分子科学系列讲座第297讲,Prof.David A Hoagland,Electron Microscopy of Dissolved, Dispersed, and Solvated Polymer Systems

文章来源:    发布时间:2019-05-13
报告题目:Electron Microscopy of Dissolved, Dispersed, and Solvated Polymer Systems (NO.PSLAB297-PS2019-12)
报 告 人:Prof.David A Hoagland
单  位:University of Massachusetts Amherst, USA

While optical microscopy allows the structure and dynamics of solvent-containing materials to be visualized down to the diffraction limit of light, about 300 nm, a comparable microscopy method for imaging at smaller length scales is lacking. The obvious choice, electron microscopy, imposes high vacuum, making the method incompatible with specimens containing volatile components. To bypass this vacuum, considerable attention has been directed to liquid cells for transmission electron microscopy. Here, another approach is outlined, one that exploits the nonvolatility of ionic liquids and the lower energy electrons of scanning electron microscopy. Structure and dynamics (captured as movies) of growing crystals, polymer gels, and ligand-coating nanoparticles are thereby obtained at high resolution (about 3-5 nm) and reasonable frame rates (about 2 fps) under conditions that stabilize specimens over minutes to hours without beam damage. A particular focus has been dispersed nanoparticle-decorated liquid interfaces, where nanoparticle interactions and packing have been probed as functions of areal fraction, particle shape and composition, and ligand identity.

 Prof.David A Hoagland


David A. Hoagland received his B.S. degree in Chemical Engineering from Stanford University in 1980, and Ph.D. in Chemical Engineering from Prinston University in 1986. He was an assistant professor at PSE UMass from 1985 to 1991, an associate professor from 1991-2003, and has been a full professor since 2003. He has published numerous papers in professional journals, including Science, PRL, and Macromolecules, and authored many book sections. He was elected American Physical Society fellow in 2002, and awarded Sigma Xi Distinguished National Lecturer for 2004-2007. His research interests are: Polyelectrolytes, Polymer Solutions and Gels, Advanced Polymer Characterization Methods, Polymer-Based Sensors of Water Quality, Single Molecule Visualizations, Aqueous Polymer, Polymers in Ionic Liquids.