Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
201511 | Fluid Phase Equilibria | 2013 | 7 Pages |
The impact of severe spatial confinement on the phase transition behavior of smectic liquid crystals has been systematically studied. Dodecylcyanobiphenyl (12CB) and octylcyanobiphenyl (8CB) liquid crystals were confined to controlled-pore glasses of various pore radii R. The phase transition behavior was studied by means of high-resolution ac calorimetry. The results show that the carbon tails length of the liquid crystal molecules strongly influences the phase behavior. In 8CB samples strong pretransitional effects were observed; however, these effects were substantially weaker in 12CB samples. Moreover, a crossover between first and second order phase transition character was observed in 12CB samples upon decreasing R. The observed behavior is explained in terms of surface-memory effects and a dimensional crossover.
► Observed qualitatively different phase behavior is due to surface memory effects. ► Molecules with relatively long alkyl chains exhibit weak wetting interaction. ► In severely confined samples dimensional-crossover could be observed.