The Nematic to Isotropic Phase Transition in an Organic Random Network

The 4′-n-pentyl-4-cyanobiphenyl (5CB) liquid crystal is confined to the random interconnected voids of fibrous Millipore filter paper. The nematic to isotropic (NI) transition is studied using an ac calorimetry technique on Millipore filters of various void sizes. Even though the nematic correlation length is much smaller than all of the Millipore void sizes employed, substantial differences from the bulk behavior occur at the NI transition.