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Monodisperse glassy liquid crystalline conjugated
oligomer films are promising for application in
optics, photonics and electronics. This research has
furnished fundamental understanding of the origin of
chiroptical effects in glassy-cholesteric
oligofluorene films and new insight into the
photoalignment of glassy-nematic oligofluorene films.
Specifically, cholesteric films, which emerged upon
thermal annealing of spin-cast films of chiral
oligofluorenes, showed an order-of-magnitude increase
in circular dichroism and a handedness reversal in
circularly polarized fluorescence compared to the
amorphous pristine films. The oligomer chain length
played an important role in solid morphology. The
orientation of monodisperse glassy-nematic
oligofluorenes was characterized on photoalignment
layers comprising a polymethacrylate backbone with
coumarin pendants. A transition from a parallel to a
perpendicular orientation with reference to the
polarization axis of UV-irradiation was observed at a
high extent of coumarin dimerization. A kinetic model
was used to interpret the photodimerization of
coumarin and to evaluate the relative importance of
the factors affecting the crossover behavior.

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