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A Multitechnique Study of Structure and Dynamics of Polyfluorene Cast Films and the Influence on Their Photoluminescence

Faria, Gregorio C.; Plivelic, Tomás LU ; Cossiello, Rafael F.; Souza, André A.; Atvars, Tereza D. Z.; Torriani, Iris L. and deAzevedo, Eduardo R. (2009) In The Journal of Physical Chemistry Part B 113(33). p.11403-11413
Abstract
This article describes the microstructure and dynamics in the solid state of polyfluorene-based polymers, poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO), a semicrystalline polymer, and poly[(9,9-dioctyl-2,7-divinylene-fluorenylene)-alt-co-{2-methoxy-5-(2-ethyl-hexyloxy)-1,4-phenylene vinylene}, a copolymer with mesomorphic phase properties. These structures were determined by wide-angle X-ray scattering (WAXS) measurements. Assuming a packing model for the copolymer structure, where the planes of the phenyl rings are stacked and separated by an average distance of 4.5 Å and laterally spaced by about 16 Å, we followed the evolution of these distances as a function of temperature using WAXS and associated the changes observed to the polymer... (More)
This article describes the microstructure and dynamics in the solid state of polyfluorene-based polymers, poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO), a semicrystalline polymer, and poly[(9,9-dioctyl-2,7-divinylene-fluorenylene)-alt-co-{2-methoxy-5-(2-ethyl-hexyloxy)-1,4-phenylene vinylene}, a copolymer with mesomorphic phase properties. These structures were determined by wide-angle X-ray scattering (WAXS) measurements. Assuming a packing model for the copolymer structure, where the planes of the phenyl rings are stacked and separated by an average distance of 4.5 Å and laterally spaced by about 16 Å, we followed the evolution of these distances as a function of temperature using WAXS and associated the changes observed to the polymer relaxation processes identified by dynamical mechanical thermal analysis. Specific molecular motions were studied by solid-state nuclear magnetic resonance. The onset of the side-chain motion at about 213 K (β-relaxation) produced a small increase in the lateral spacing and in the stacking distance of the phenyl rings in the aggregated structures. Besides, at about 383 K (α-relaxation) there occurs a significant increase in the amplitude of the torsion motion in the backbone, producing a greater increase in the stacking distance of the phenyl rings. Similar results were observed in the semicrystalline phase of PFO, but in this case the presence of the crystalline structure affects considerably the overall dynamics, which tends to be more hindered. Put together, our data explain many features of the temperature dependence of the photoluminescence of these two polymers. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
NMR, WAXS, molecular dynamics, supramolecular structure, electroluminescent polymer
in
The Journal of Physical Chemistry Part B
volume
113
issue
33
pages
11403 - 11413
publisher
The American Chemical Society
external identifiers
  • wos:000268907600008
  • scopus:70349241665
ISSN
1520-5207
DOI
10.1021/jp9043368
language
English
LU publication?
yes
id
aaed8f75-63c8-44cc-89d0-37f05a454aca (old id 1455093)
date added to LUP
2009-08-31 07:53:30
date last changed
2017-11-05 04:13:05
@article{aaed8f75-63c8-44cc-89d0-37f05a454aca,
  abstract     = {This article describes the microstructure and dynamics in the solid state of polyfluorene-based polymers, poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO), a semicrystalline polymer, and poly[(9,9-dioctyl-2,7-divinylene-fluorenylene)-alt-co-{2-methoxy-5-(2-ethyl-hexyloxy)-1,4-phenylene vinylene}, a copolymer with mesomorphic phase properties. These structures were determined by wide-angle X-ray scattering (WAXS) measurements. Assuming a packing model for the copolymer structure, where the planes of the phenyl rings are stacked and separated by an average distance of 4.5 Å and laterally spaced by about 16 Å, we followed the evolution of these distances as a function of temperature using WAXS and associated the changes observed to the polymer relaxation processes identified by dynamical mechanical thermal analysis. Specific molecular motions were studied by solid-state nuclear magnetic resonance. The onset of the side-chain motion at about 213 K (β-relaxation) produced a small increase in the lateral spacing and in the stacking distance of the phenyl rings in the aggregated structures. Besides, at about 383 K (α-relaxation) there occurs a significant increase in the amplitude of the torsion motion in the backbone, producing a greater increase in the stacking distance of the phenyl rings. Similar results were observed in the semicrystalline phase of PFO, but in this case the presence of the crystalline structure affects considerably the overall dynamics, which tends to be more hindered. Put together, our data explain many features of the temperature dependence of the photoluminescence of these two polymers.},
  author       = {Faria, Gregorio C. and Plivelic, Tomás and Cossiello, Rafael F. and Souza, André A. and Atvars, Tereza D. Z. and Torriani, Iris L. and deAzevedo, Eduardo R.},
  issn         = {1520-5207},
  keyword      = {NMR,WAXS,molecular dynamics,supramolecular structure,electroluminescent polymer},
  language     = {eng},
  number       = {33},
  pages        = {11403--11413},
  publisher    = {The American Chemical Society},
  series       = {The Journal of Physical Chemistry Part B},
  title        = {A Multitechnique Study of Structure and Dynamics of Polyfluorene Cast Films and the Influence on Their Photoluminescence},
  url          = {http://dx.doi.org/10.1021/jp9043368},
  volume       = {113},
  year         = {2009},
}