Forces in nematic liquid crystals: from nanoscale interfacial forces to long-range forces in nematic colloids

Abstract

In this paper we give an overview of experiments that provided an insight into the nature of forces between surfaces and objects in a nematic liquid crystal. These forces, also called ‘structural forces’, are the consequence of the long-range orientational order and orientational elasticity of nematic liquid crystals. Owing to their fundamental as well as technological importance, forces between objects in liquid crystals have been a subject of growing interest during the last decade. Experimental observations and studies of structural forces are described from nanoscale interfacial forces, measured by an atomic force microscope, to the micro-scale forces between colloidal particles in nematics, studied by laser tweezers and optical video microscopy.

Keywords:

• forces in liquid crystals
• interfacial forces
• nematic colloids

Acknowledgement

First of all, I would like to thank Klemen Kočevar for his valuable contribution to the field of interfacial forces in liquid crystals, and Miha Škarabot for his valuable contribution to our understanding of nematic colloids. I would also like to thank Miha Ravnik, Slobodan Žumer, Uroš Tkalec, Igor Poberaj, Dušan Babič, Natan Osterman, Andriy Nych, Ulyana Ognysta and Vassili Nazarenko for their contributions.

Notes

Professor Musevic received the 2008 Samsung Mid-Career award for his work on the physical studies of antiferroelectric and ferroelectric liquid crystals, measurements of interfacial forces, colloidal particles and their manipulation in nematic liquid crystals.