A nematic liquid crystal in cylindrical pores of polycarbonate (Nuclepore) membranes with radii 25–400 nm was studied by dynamic light scattering. The fundamental mode of the orientational fluctuations shows a crossover from bulk behavior, dominated by bulk-elastic constant $K$, to a surface-dominated one, in which the relaxation rate is determined by the ratio of surface-anchoring strength $W$ and viscosity $\eta$. In the smallest pores, the contribution of surface viscosity $\zeta$ is also significant. The surface extrapolation length $K/W$ goes approximately as $({T-T}_{\mathrm{NI}}{)}^{-1\mathrm{}}$. The characteristic length for surface viscosity $\zeta /\eta$ is of the order of 10 nm.

• Received 1 April 1998

DOI:https://doi.org/10.1103/PhysRevLett.81.5844