Self-assembly and molecular dynamics of oligoindenofluorenes

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 di-electric spectroscopy. Oligomers of indenofluorenes possess high structural order and form smectic mesophases, as opposed to the nematic mesophases formed in the corresponding oligofluorenes. The a-process associated with the liquid-to-glass transition displays an asymmetric broadening of relaxation times (non- Debye process), with a non-Arrhenius temperature dependance of relaxation times and a strong molecular weight dependance. The low dielectric loss and low ionic conductivity revealed the absence of ketone structural defects, which is consistent with the observed stable blue emission.