Mechanically Generated Surface Chirality at the Nanoscale

Sameh Ferjani, Yoonseuk Choi, Joel Pendery, Rolfe G. Petschek, Charles Rosenblatt
2010 Physical Review Letters  
A substrate coated with an achiral polyimide alignment layer was scribed bidirectionally with the stylus of an atomic force microscope to create an easy axis for liquid crystal orientation. The resulting non-centrosymmetric topography resulted in a chiral surface that manifests itself at the molecular level. To show this unambiguously, a planar-aligned negative dielectric aniostropy achiral nematic liquid crystal was placed in contact with the surface and subjected to an electric field . The
more » ... tric field . The nematic director was found to undergo an azimuthal rotation approximately linear in  . This so-called "surface electroclinic effect" is a signature of 2D chirality and was not observed when the polyimide was treated for a centrosymmetric topography, and therefore was nonchiral.
doi:10.1103/physrevlett.104.257801 pmid:20867414 fatcat:dpqg6cg4ozdrnpyrxpnsswm2hm