Influence of side chain length on the self-assembly of hairy-rod poly(9,9-dialkylfluorene)s in the poor solvent methylcyclohexane

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Abstract

We report on the phase behavior of poly(9,9-dihexylfluorene) (PF6), poly(9,9-diheptylfluorene) (PF7), poly(9,9-diocylfluorene) (PF8) poly(9,9-dinonylfluorene) (PF9), and poly(9,9-didecylfluorene) (PF10) in methylcyclohexane (MCH). After a heating-cooling cycle, in the 10-50 mg/mL. concentration range. PF6/ MCH. PF7/MCH. PF8/MCH, and PF9/MCH systems were found to be gel-like, while PF10/MCH appears less viscous. PF6/MCH, PF7/MCH, PF8/MCH, and PF9/MCH form large (10- 100 nm) sheetlike assemblies (thickness of 2-3 nm). The larger length scale Structures of these sheets show an odd-even dependence on the side chain (spacer) length: the PF6 and PF8 sheets are broader and thinner, whereas PF7 and PF9 sheets are thicker with a Putative double layer Structure. PF10 does not follow this sequence, and only part of the polymer is assembled into a sheetlike structure the rest remaining dissolved at the molecular level. PF8/MCH and PF9/MCH mixtures also have lower length scale crystalline structures with an internal period corresponding to the periodicity observed in the solid-state P phase of PF8. Vestiges of crystalline domains are found for PF6 and PF7 but not for PF10. PF7/MCH. PF8/MCH, and PF9/MCH systems contain the conformational isomer C, of those chains observed in the ss phase, while this is not observed with other polymer/MCH systems.

Details

Authors
  • Matti Knaapila
  • F. B. Dias
  • V. M. Garamus
  • L. Almasy
  • M. Torkkeli
  • K. Leppanen
  • F. Galbrecht
  • E. Preis
  • H. D. Burrows
  • U. Scherf
  • A. P. Monkman
Organisations
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Natural Sciences
  • Physical Sciences
Original languageEnglish
Pages (from-to)9398-9405
JournalMacromolecules
Volume40
Issue number26
Publication statusPublished - 2007
Publication categoryResearch
Peer-reviewedYes