CALORIMETRIC STUDY OF PHASE-TRANSITIONS IN CONFINED LIQUID-CRYSTALS

Using an ac calorimetry technique we measured the specific heat at the nematic-isotropic, smectic-A-nematic, and smectic-A-isotropic phase transitions, for the alkylcyanobiphenyl liquid crystal nCB series confined to the 0.2-mum-diam pores of Anopore membranes. Studies were also performed as a function of nematic director alignment within the pores. Novel effects regarding specific-heat amplitudes, transition-temperature shifts, and broadening and rounding of phase transitions are found. They are strongly dependent on the director orientation and on the order of the phase transition.