Network structure of polyfluorene sheets as a function of alkyl side chain length

M. Knaapila, D. W. Bright, R. Stepanyan, M. Torkkeli, L. Almásy, R. Schweins, U. Vainio, E. Preis, F. Galbrecht, U. Scherf, A. P. Monkman

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

The formation of self-organized structures in poly(9,9-di-n-alkylfluorene)s ∼1 vol % methylcyclohexane (MCH) and deuterated MCH (MCH-d14) solutions was studied at room temperature using neutron and x-ray scattering (with the overall q range of 0.00058-4.29 -1) and optical spectroscopy. The number of side chain carbons (N) ranged from 6 to 10. The phase behavior was rationalized in terms of polymer overlap, cross-link density, and blending rules. For N=6-9, the system contains isotropic areas and lyotropic areas where sheetlike assemblies (lateral size of >400) and free polymer chains form ribbonlike agglomerates (characteristic dimension of >1500) leading to a gel-like appearance of the solutions. The ribbons are largely packed together with surface fractal characteristics for N=6-7 but become open networklike structures with mass fractal characteristics for N=8-9, until the system goes through a transition to an isotropic phase of overlapping rodlike polymers for N=10. The polymer order within sheets varies allowing classification for loose membranes and ordered sheets, including the so-called β phase. The polymers within the ordered sheets have restricted motion for N=6-7 but more freedom to vibrate for N=8-9. The nodes in the ribbon network are suggested to contain ordered sheets cross-linking the ribbons together, while the nodes in the isotropic phase appear as weak density fluctuations cross-linking individual chains together. The tendencies for macrophase separation and the formation of non beta sheets decrease while the proportion of free chains increases with increasing N. The fraction of β phase varies nonlinearly, reaching its maximum at N = 8.

Original languageEnglish
Article number051803
JournalPhysical Review E - Statistical, Nonlinear, and Soft Matter Physics
Volume83
Issue number5
DOIs
Publication statusPublished - May 19 2011

Fingerprint

Network Structure
Polymers
ribbons
polymers
Linking
Fractal
fractals
Vary
Vibrate
x ray scattering
Vertex of a graph
Neutron
assemblies
Overlapping
Spectroscopy
Overlap
Lateral
proportion
Carbon
tendencies

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Statistical and Nonlinear Physics
  • Statistics and Probability

Cite this

Network structure of polyfluorene sheets as a function of alkyl side chain length. / Knaapila, M.; Bright, D. W.; Stepanyan, R.; Torkkeli, M.; Almásy, L.; Schweins, R.; Vainio, U.; Preis, E.; Galbrecht, F.; Scherf, U.; Monkman, A. P.

In: Physical Review E - Statistical, Nonlinear, and Soft Matter Physics, Vol. 83, No. 5, 051803, 19.05.2011.

Research output: Contribution to journalArticle

Knaapila, M, Bright, DW, Stepanyan, R, Torkkeli, M, Almásy, L, Schweins, R, Vainio, U, Preis, E, Galbrecht, F, Scherf, U & Monkman, AP 2011, 'Network structure of polyfluorene sheets as a function of alkyl side chain length', Physical Review E - Statistical, Nonlinear, and Soft Matter Physics, vol. 83, no. 5, 051803. https://doi.org/10.1103/PhysRevE.83.051803
Knaapila, M. ; Bright, D. W. ; Stepanyan, R. ; Torkkeli, M. ; Almásy, L. ; Schweins, R. ; Vainio, U. ; Preis, E. ; Galbrecht, F. ; Scherf, U. ; Monkman, A. P. / Network structure of polyfluorene sheets as a function of alkyl side chain length. In: Physical Review E - Statistical, Nonlinear, and Soft Matter Physics. 2011 ; Vol. 83, No. 5.
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