Abstract
The phase behavior of pentylcyanobiphenyl (5CB) and octylcyanobiphenyl (8CB) liquid crystals confined to controlled porous glass of different characteristic void sizes $R$ is studied using deuteron NMR. In samples with the 5CB liquid crystal the discontinuous isotropic-nematic $(I\ensuremath{-}N)$ transition becomes gradual for $Rl0.025\ensuremath{\mu}\mathrm{m}.$ The discontinuous $I\ensuremath{-}N$ phase transition temperature shift $\ensuremath{\Delta}{T}_{\mathrm{IN}}$ scales as $\ensuremath{\Delta}{T}_{\mathrm{IN}}\ensuremath{\propto}{R}^{\ensuremath{-}1.3\ifmmode\pm\else\textpm\fi{}0.3}.$ A detailed theoretical analysis of the origins of the temperature shift and the change of the character of the $I\ensuremath{-}N$ and nematic--smectic-$A$ phase transition is given. The influence of the surface treatment is studied for the 8CB liquid crystal immersed in a $R=0.2\ensuremath{\mu}\mathrm{m}$ matrix. The results suggest that for the silane-treated sample the anchoring is homeotropic, whereas it is planar for the nontreated surface. In both cases the corresponding anchoring strength is estimated to be larger than ${10}^{\ensuremath{-}5}{\mathrm{J}/\mathrm{m}}^{2}.$ The smectic-$A$ ordering seems to be more affected by the confinement in the nontreated sample than the one treated by silane.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
