The photoalignment of a series of monodisperse glassy-nematic oligofluorenes was investigated on coumarin-containing polymer films in the parallel regime. The orientational order parameter of a spin-cast oligofluorene film, S_OF, was found to decrease with an increasing oligofluorene length because of the increasing demand on Y_dS_d, the product of coumarin dimers' concentration and orientation order parameter. In addition, an increased annealing temperature demanded by a longer oligofluorene caused an orientational relaxation of coumarin dimers to a greater extent. Nonetheless, under favorable conditions S_OF values of penta, hepta-, and nonafluorenes are comparable to those achieved on rubbed polyimide films.

Date Published: 12 September 2007
PDF: 8 pages
Proc. SPIE 6654, Liquid Crystals XI, 665409 (12 September 2007); doi: 10.1117/12.734852

Published in SPIE Proceedings Vol. 6654:
Liquid Crystals XI
Iam Choon Khoo, Editor(s)