title: Self-assembly and molecular dynamics of oligoindenofluorenes.
abstract: The optical properties, self-assembly mechanism, thermal properties, and the associated molecular dynamics of a series of stable blue-emitting oligoindenofluorenes up to the polymer were investigated by photoluminescence, wide-angle X-ray scattering, polarizing optical microscopy, differential scanning calorimetry, and dielectric spectroscopy. Oligomers of indenofluorenes possess high structural order and form smectic mesophases, as opposed to the nematic mesophases formed in the corresponding oligofluorenes. The alpha process associated with the liquid-to-glass transition displays an asymmetric broadening of relaxation times (non-Debye process), with a non-Arrhenius temperature dependence of relaxation times and a strong molecular weight dependence. The low dielectric loss and low ionic conductivity revealed the absence of ketone structural defects, which is consistent with the observed stable blue emission.
authors.affiliation: Department of Physics and Foundation for Research and Technology-Hellas, Biomedical Research Institute (FORTH-BRI), University of Ioannina, P.O. Box. 1186, 45110 Ioannina, Greece.
authors.forename: Mahdy M
authors.initials: MM
authors.lastname: Elmahdy
authors.forename: George
authors.initials: G
authors.lastname: Floudas
authors.forename: Luke
authors.initials: L
authors.lastname: Oldridge
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Grimsdale
authors.forename: Klaus
authors.initials: K
authors.lastname: Müllen
mesh_terms: D002152:Calorimetry, Differential Scanning / Q000379:methods; D002627:Chemistry, Physical / Q000379:methods*; D019281:Dimerization; D004553:Electric Conductivity; D005449:Fluorenes / Q000737:chemistry*; D005898:Glass; D007477:Ions; D008968:Molecular Conformation; D010777:Photochemistry / Q000379:methods; D012542:Scattering, Radiation; D013053:Spectrophotometry; D013056:Spectrophotometry, Ultraviolet; D013499:Surface Properties; D013696:Temperature; D014965:X-Rays
chemical_list: D005449:Fluorenes; D007477:Ions