Virtual isotropic‐nematic transitions in alkyl cyanobiphenyls

Abstract

Pretransitional fluctuations in the isotropic phase of liquid crystalline and non‐liquid crystalline alkyl cyanobiphenyls have been investigated using light scattering and magnetic birefringence measurements. We find evidence for a virtual isotropic‐nematic phase transition in short‐chain alkyl cyanobiphenyls with no observable nematic phase. The measured temperature dependence of fluctuations is well‐described by mean‐field theory. Virtual phase transition temperatures extrapolated from separate light scattering and magnetic birefringence experiments are in good agreement. Landau–de Gennes model parameters for the compounds investigated are calculated from the experimental results.

Keywords:

• virtual phase transition
• liquid crystal phase transition
• magnetic birefringence
• light scattering

Acknowledgements

This work was supported in part by grants from the Research Corporation and the National Science Foundation, Grant. No. DMR‐9307350.