Memory Effects and Multistability in Alignment of Nematics at Surfaces with Inhomogeneous Random Anchoring

Abstract

Alignment mechanisms for nematics at a macroscopically isotropic polymer surface are studied in cells where the second surface provides strong anchoring. Surface morphology of tested surfaces was studied using Atomic Force Microscopy and Scanning Electron Microscopy. We observed in polarizing microscope that the temperature gradient across the cell during transition from isotropic to nematic state strongly affects the alignment at the tested surface. We present a model that explains the temperature gradient effect. The initial patterns formed at the tested surface recover after multiple phase transitions but they can be erased by the temperature exposure well above the nematic-isotropic transition.

Keywords:

• anchoring
• memory effect
• nematic liquid crystal
• random surface

Acknowledgments

Author is grateful to Yuri Reznikov and Ivan Dozov for useful discussions, to Oleg Lavrentovich and Liou Qiu for help with SEM and AFM measurements, and to Igor Gerus for synthesis of the polymers.