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Nematic liquid crystal alignment on chemical patterns

2007; Taylor & Francis; Volume: 34; Issue: 9 Linguagem: Inglês

10.1080/02678290701614665

1366-5855

Jonathan P. Bramble, Stephen D. Evans, J. R. Henderson, C. Anquetil, Douglas J. Cleaver, Nathan J. Smith,

Electrowetting and Microfluidic Technologies

Patterned Self‐Assembled Monolayers (SAMs) promoting both homeotropic and planar degenerate alignment of 6CB and 9CB in their nematic phase were created using microcontact printing of functionalized organothiols on gold films. The effects of a range of different pattern geometries and sizes were investigated, including stripes, circles and checkerboards. Evanescent wave ellipsometry was used to study the orientation of the liquid crystal (LC) on these patterned surfaces during the isotropic‐nematic phase transition. Pretransitional growth of a homeotropic layer was observed on 1 µm homeotropic aligning stripes, followed by a homeotropic monodomain state prior to the bulk phase transition. Accompanying Monte Carlo simulations of LCs aligned on nanoscale‐patterned surfaces were also performed. These simulations also showed the presence of the homeotropic monodomain state prior to the transition.