Meridional orientation in biaxially aligned thin films of hairy-rod polyfluorene

Research output: Contribution to journalArticle

Abstract

The uniaxial chain alignment and equatorial patterning of poly [9,9-bis(2-ethylhexyl)fluorene-2,7-diyl] (M-n = 29 kg/mol, M-w = 68 kg/mol) thin films atop rubbed polyimide substrates have been studied by grazing incidence X-ray diffraction. This specific molecular weight yields among the highest observed levels of chain alignment and optical anisotropy and, after thermal annealing, the sample undergoes transformation to a highly textured crystalline hexagonal phase. The two dominant equatorial orientations (i.e., types I and II crystallites) are found to have almost identical meridional orientation distributions. The X-ray deduced orientation is in quantitative agreement with that obtained by optical absorption measurements. It is also shown that the equatorial ordering is paracrystalline in nature, and both type I and type II crystallites are similar in this respect. This equatorial scattering is superimposed on a background of a hexagonal phase polymer with a cylindrically isotropic orientation (type III).

Details

Authors
  • Matti Knaapila
  • Thomas P. A. Hase
  • Mika Torkkeli
  • Roman Stepanyan
  • Laurence Bouchenoire
  • Hyeun-Seok Cheun
  • Michael J. Winokur
  • Andrew P. Monkman
Organisations
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Natural Sciences
  • Physical Sciences
Original languageEnglish
Pages (from-to)1706-1711
JournalCrystal Growth & Design
Volume7
Issue number9
Publication statusPublished - 2007
Publication categoryResearch
Peer-reviewedYes