Anchoring of 4-n-alkyl-4′-cyanobiphenyl liquid crystal molecules on rubbed polyimides

Abstract

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 ≈ 78° 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.