Optical force-based detection of splay and twist viscoelasticity of CCN47 across the Nematic-to-Smectic A transition

摘要

We measured the splay and twist elastic constant K and viscosity. of CCN47 by coupling optical forces with the nematic director and detecting the resulting deformation. This approach enables to separately induce each of the two distortions and allows to characterize the viscoelastic properties of both the nematic and the smectic A phase. We find that in the nematic phase far from the transition the splay elastic constant K-1 is larger than that of twist K-2, while its viscosity is smaller,eta(splay)