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Structural study of...
Structural study of helical polyfluorene under high quasihydrostatic pressure
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Knaapila, M. (författare)
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Konopkova, Z. (författare)
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Torkkeli, M. (författare)
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- Haase, Dörthe (författare)
- Lund University,Lunds universitet,MAX IV-laboratoriet,MAX IV Laboratory
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Liermann, H. -P. (författare)
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Guha, S. (författare)
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Scherf, U. (författare)
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(creator_code:org_t)
- 2013
- 2013
- Engelska.
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Ingår i: Physical Review E (Statistical, Nonlinear, and Soft Matter Physics). - 1539-3755. ; 87:2
- Relaterad länk:
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http://dx.doi.org/10...
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https://lup.lub.lu.s...
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https://doi.org/10.1...
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Abstract
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- 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
Ämnesord
- NATURVETENSKAP -- Fysik (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences (hsv//eng)
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