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Observation of the β ‐Phase in Two Short‐Chain Oligofluorenes
Author(s) -
Tsoi Wing C.,
Charas Ana,
Cadby Ashley J.,
Khalil Gamal,
Adawi Ali M.,
Iraqi Ahmed,
Hunt Barry,
Morgado Jorge,
Lidzey David G.
Publication year - 2008
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.200700530
Subject(s) - pentamer , oligomer , materials science , monomer , fluorene , planarity testing , phase (matter) , chain (unit) , polymer , chemical physics , polymer chemistry , crystallography , organic chemistry , physics , composite material , chemistry , nuclear magnetic resonance , astronomy
The polymer poly(9,9‐dioctylfluorene) (PF8) can be driven into a morphological form termed the β ‐phase that has enhanced planarity and increased structural rigidity. We show that the β ‐phase can be generated in two different fluorene oligomers; a fluorene pentamer, and a short (statistical) oligomer composed of chains having a maximum length of 19 monomer units. By comparing the energy of the zero‐zero phonon line in fluorescence from the β ‐phase oligomers with that in the PF8 polymer, we show that the electronic conjugation length of the β ‐phase is (30 ± 12) monomer‐units, a value consistent with the persistence length of the molecular chain.