The browser you are using is not supported by this website. All versions of Internet Explorer are no longer supported, either by us or Microsoft (read more here: https://www.microsoft.com/en-us/microsoft-365/windows/end-of-ie-support).

Please use a modern browser to fully experience our website, such as the newest versions of Edge, Chrome, Firefox or Safari etc.

Structural study of helical polyfluorene under high quasihydrostatic pressure

På svenska

Author

  • M. Knaapila
  • Z. Konopkova
  • M. Torkkeli
  • Dörthe Haase
  • H. -P. Liermann
  • S. Guha
  • U. Scherf

Summary, in English

We report on an x-ray diffraction (XRD) study of helical poly[9,9-bis(2-ethylhexyl)fluorene] (PF2/6) under high quasihydrostatic pressure and show an effect of pressure on the torsion angle (dihedral angle) between adjunct repeat units and on the hexagonal unit cell. A model for helical backbone conformation is constructed. The theoretical position for the most prominent 00l x-ray reflection is calculated as a function of torsion angle. The XRD of high molecular weight PF2/6 (M-n = 30 kg/mol) is measured through a diamond anvil cell upon pressure increase from 1 to 10 GPa. The theoretically considered 00l reflection is experimentally identified, and its shift with the increasing pressure is found to be consistent with the decreasing torsion angle between 2 and 6 GPa. This indicates partial backbone planarization towards a more open helical structure. The h00 peak is identified, and its shift together with the broadening of 00l implies impairment of the ambient hexagonal order, which begins at or below 2 GPa. Previously collected high-pressure photoluminescence data are reanalyzed and are found to be qualitatively consistent with the XRD data. This paper provides an example of how the helical pi-conjugated backbone structure can be controlled by applying high quasihydrostatic pressure without modifications in its chemical structure. Moreover, it paves the way for wider use of high-pressure x-ray scattering in the research of pi-conjugated polymers. DOI: 10.1103/PhysRevE.87.022602

Department/s

Publishing year

2013

Language

English

Publication/Series

Physical Review E (Statistical, Nonlinear, and Soft Matter Physics)

Volume

87

Issue

2

Document type

Journal article

Publisher

American Physical Society

Topic

  • Physical Sciences
  • Natural Sciences

Status

Published

ISBN/ISSN/Other

  • ISSN: 1539-3755