Room-temperature processing of π-conjugated oligomers into uniaxially oriented monodomain films on coumarin-based photoalignment layers.

Photoalignment layers comprising Polymer 1 were prepared using linearly polarized UV-irradiation for chloroform-vapor annealing of π-conjugated oligomer films, both processes conducted at room temperature. The resultant uniaxially oriented monodomain films exhibited S = 0.74 (at Pr = 0.90) and 0.82 (at Pr = 0.95) in OF and OF2T films, respectively, apparently limited by film dewetting in comparison to S = 0.82 ± 0.01 from thermal annealing on rubbed polyimide alignment and Polymer 1 photoalignment layers. The time to arrive at maximum S values varied from 5-10 s to 6-8 min on rubbed polyimide alignment layers and Polymer 1 photoalignment layer, respectively, because of favorable π-π interactions enhanced by rubbing. In contrast, PF2T could not be oriented on either type of alignment layers after annealing under saturated chloroform vapor up to 14 h. Annealing of an OF2T film under saturated chlorobenzene vapor at room temperature permitted lyotropic nematic mesomorphism to be observed in situ, which is equivalent to thermotropic nematic mesomorphism as the driving force behind thermal annealing. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011 [ABSTRACT FROM AUTHOR]