title: Polyvinylidene fluoride molecules in nanofibers, imaged at atomic scale by aberration corrected electron microscopy.
abstract: Atomic scale features of polyvinylidene fluoride molecules (PVDF) were observed with aberration corrected transmission electron microscopy. Thin, self-supporting PVDF nanofibers were used to create images that show conformations and relative locations of atoms in segments of polymer molecules, particularly segments near the surface of the nanofiber. Rows of CF2 atomic groups, at 0.25 nm intervals, which marked the paths of segments of the PVDF molecules, were seen. The fact that an electron microscope image of a segment of a PVDF molecule depended upon the particular azimuthal direction, along which the segment was viewed, enabled observation of twist around the molecular axis. The 0.2 nm side-by-side distance between the two fluorine atoms attached to the same carbon atom was clearly resolved. Morphological and chemical changes produced by energetic electrons, ranging from no change to fiber scission, over many orders of magnitude of electrons per unit area, promise quantitative new insights into radiation chemistry. Relative movements of segments of molecules were observed. Promising synergism between high resolution electron microscopy and molecular dynamic modeling was demonstrated. This paper is at the threshold of growing usefulness of electron microscopy to the science and engineering of polymer and other molecules.
authors.affiliation: Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, OH 44313, USA.
authors.forename: Dinesh
authors.initials: D
authors.lastname: Lolla
authors.affiliation: Department of Polymer Science, The University of Akron, Akron, OH 44313, USA. reneker@uakron.edu.
authors.forename: Joseph
authors.initials: J
authors.lastname: Gorse
authors.affiliation: The Molecular Foundry and Joint Center for Artificial Photosynthesis, Lawrence Berkeley National Laboratory, One Cyclotron Rd, Berkeley CA 94720, USA.
authors.forename: Christian
authors.initials: C
authors.lastname: Kisielowski
authors.affiliation: Department of Physics, Case Western Reserve University, Cleveland, OH 44106, USA.
authors.forename: Jiayuan
authors.initials: J
authors.lastname: Miao
authors.affiliation: Department of Physics, Case Western Reserve University, Cleveland, OH 44106, USA.
authors.forename: Philip L
authors.initials: PL
authors.lastname: Taylor
authors.affiliation: Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, OH 44313, USA.
authors.forename: George G
authors.initials: GG
authors.lastname: Chase
authors.affiliation: Department of Polymer Science, The University of Akron, Akron, OH 44313, USA. reneker@uakron.edu.
authors.forename: Darrell H
authors.initials: DH
authors.lastname: Reneker