ANCHORING OF 4-N-ALKYL-4'-CYANOBIPHENYL LIQUID-CRYSTAL MOLECULES ON RUBBED POLYIMIDES

In the literature it has been reported that the rigid cyanobiphenyl core of 4-n-alkyl-4'-cyanobiphenyl molecules deposited onto polyimide-coated substrates makes an average angle of approximate to 78 degrees with respect to the surface normal independent of the rubbing conditions applied and independent of the polyimide materials studied. A simple anchoring model based on a combination of dipole-dipole, van der Waals and steric interactions explains this angle.