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Effect of side-chain asymmetry on the intermolecular structure and order-disorder transition in alkyl-substituted polyfluorenes

Knaapila, M. LU ; Stepanyan, R.; Torkkeli, M.; Haase, D. LU ; Fröhlich, N.; Helfer, A.; Forster, M. and Scherf, U. (2016) In Physical Review E - Statistical, Nonlinear, and Soft Matter Physics 93(4).
Abstract

We study relations among the side-chain asymmetry, structure, and order-disorder transition (ODT) in hairy-rod-type poly(9,9-dihexylfluorene) (PF6) with two identical side chains and atactic poly(9-octyl-9-methyl-fluorene) (PF1-8) with two different side chains per repeat. PF6 and PF1-8 organize into alternating side-chain and backbone layers that transform into an isotropic phase at TODT(PF6) and TbiODT(PF1-8). We interpret polymers in terms of monodisperse and bidisperse brushes and predict scenarios TODT<TbiODT and TODT∼TbiODT for high and low grafting densities (the side-chain length above or below the average grafting distance). Calorimetry and x-ray scattering indicate the condition TODT(PF6)∼TbiODT(PF1-8) following the low... (More)

We study relations among the side-chain asymmetry, structure, and order-disorder transition (ODT) in hairy-rod-type poly(9,9-dihexylfluorene) (PF6) with two identical side chains and atactic poly(9-octyl-9-methyl-fluorene) (PF1-8) with two different side chains per repeat. PF6 and PF1-8 organize into alternating side-chain and backbone layers that transform into an isotropic phase at TODT(PF6) and TbiODT(PF1-8). We interpret polymers in terms of monodisperse and bidisperse brushes and predict scenarios TODT<TbiODT and TODT∼TbiODT for high and low grafting densities (the side-chain length above or below the average grafting distance). Calorimetry and x-ray scattering indicate the condition TODT(PF6)∼TbiODT(PF1-8) following the low grafting prediction. PF6 side chains coming from the alternating backbone layers appear as two separate layers with thickness H(PF6), whereas PF1-8 side chains appear as an indistinguishable bilayer with a half thickness Hbilayer(PF1-8)/2≈H(PF6). The low grafting density region is structurally possible but not certain for PF6 and confirmed for PF1-8.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics
volume
93
issue
4
publisher
American Physical Society
external identifiers
  • scopus:84964595246
  • wos:000374963100003
ISSN
1539-3755
DOI
10.1103/PhysRevE.93.042504
language
English
LU publication?
yes
id
03846ed4-1d9d-415a-b7ad-7d7c0e180811
date added to LUP
2016-09-30 10:54:01
date last changed
2017-05-21 04:54:09
@article{03846ed4-1d9d-415a-b7ad-7d7c0e180811,
  abstract     = {<p>We study relations among the side-chain asymmetry, structure, and order-disorder transition (ODT) in hairy-rod-type poly(9,9-dihexylfluorene) (PF6) with two identical side chains and atactic poly(9-octyl-9-methyl-fluorene) (PF1-8) with two different side chains per repeat. PF6 and PF1-8 organize into alternating side-chain and backbone layers that transform into an isotropic phase at TODT(PF6) and TbiODT(PF1-8). We interpret polymers in terms of monodisperse and bidisperse brushes and predict scenarios TODT&lt;TbiODT and TODT∼TbiODT for high and low grafting densities (the side-chain length above or below the average grafting distance). Calorimetry and x-ray scattering indicate the condition TODT(PF6)∼TbiODT(PF1-8) following the low grafting prediction. PF6 side chains coming from the alternating backbone layers appear as two separate layers with thickness H(PF6), whereas PF1-8 side chains appear as an indistinguishable bilayer with a half thickness Hbilayer(PF1-8)/2≈H(PF6). The low grafting density region is structurally possible but not certain for PF6 and confirmed for PF1-8.</p>},
  articleno    = {042504},
  author       = {Knaapila, M. and Stepanyan, R. and Torkkeli, M. and Haase, D. and Fröhlich, N. and Helfer, A. and Forster, M. and Scherf, U.},
  issn         = {1539-3755},
  language     = {eng},
  month        = {04},
  number       = {4},
  publisher    = {American Physical Society},
  series       = {Physical Review E - Statistical, Nonlinear, and Soft Matter Physics},
  title        = {Effect of side-chain asymmetry on the intermolecular structure and order-disorder transition in alkyl-substituted polyfluorenes},
  url          = {http://dx.doi.org/10.1103/PhysRevE.93.042504},
  volume       = {93},
  year         = {2016},
}