Molecular orientation in Langmuir-Blodgett films of polyfumarates carrying isopropylester and isopropylamide side chains

Molecular orientation in Langmuir-Blodgett (LB) films of poly(diisopropyl fumarate) (PDiPF) and poly(isopropyl N-isopropyl fumaramate) (PiPFAE), prepared by solution polymerization and emulsifier-free emulsion polymerization, respectively, was investigated. The pi-A isotherms of both polymers indicated formation of stable Langmuir monolayers. The refractive index measurements as well as the polarized IR and UV spectroscopy of the LB films revealed that the backbones of the polymers were oriented parallel to the dipping direction of the substrate. The LB films were applied to a nematic liquid crystal alignment film, and the relationship between optical axes of the LB films and the alignment direction of the liquid crystal molecules was characterized. Utilization of PDiPF and PiPFAE as a matrix polymer for polymer dispersed liquid crystals was also examined, and a higher performance with a better contrast ratio was obtained for PiPFAE. (C) 2007 Elsevier B.V. All rights reserved.