Accession Number : ADA296872

Title :   Lattice and Defect Structures of Polymerizable Diacetylene Langmuir-Blodgett Films Studied by Scanning Force Microscopy,

Corporate Author : KENT STATE UNIV OH

Personal Author(s) : Vithana, Hemasiri ; Johnson, David ; Shih, Raymond ; Mann, J. A., Jr. ; Lando, Jerome

PDF Url : ADA296872

Report Date : 1994

Pagination or Media Count : 40

Abstract : The Scanning Force Microscope has been used to study the lattice and defect structures of multilayers of the unsaturated fatty acid, 12-8- diacetylene (10,12-Pentacosadiynoic Acid) in ambient conditions. Films were prepared by the Langmuir-Blodgett technique on ordinary microscope glass and Indium Tin Oxide coated glass. Lattice structures were deduced from the well resolved molecular images and before polymerization found to be nearly centered rectangular with lattice parameters (0.88 + or - 0.06)nm and (0.51 + or - 0.04)nm. After exposing to UV radiation for polymerization the lattice structure changed to an oblique lattice with lattice parameters (0.466 + or - 0.008)nm and (0.55 + or - 0.01)nm. Molecular level defects such as dislocations and grain boundaries were resolved in these films very clearly. Observation of these kind of defects implies that it is possible to reliably image the real surface molecules under ambient conditions. Polymerization was found to take place in one of the lattice directions and the modulation perpendicular to that direction was more pronounced than along the polymer backbone. jg p.3

Descriptors :   *CRYSTAL LATTICES, *POLYMERIZATION, *MICROSCOPY, *DEFECTS(MATERIALS), *ACETYLENE, SCANNING, ULTRAVIOLET RADIATION, MOLECULAR STATES, LAYERS, POLYMERS, STRUCTURES, FILMS, GLASS, SURFACES, DISLOCATIONS, OXIDES, IMAGES, TIN, MODULATION, INDIUM, GRAIN BOUNDARIES, FATTY ACIDS, UNSATURATED HYDROCARBONS.

Subject Categories : Polymer Chemistry
      Organic Chemistry
      Physical Chemistry
      Crystallography
      Atomic and Molecular Physics and Spectroscopy
      Optics

Distribution Statement : APPROVED FOR PUBLIC RELEASE