ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
Confinement of a nematogen in submicrometer cavities can produce substantial effects on the nematic-isotropic phase transition and on order and orientation of the nematic phase. We combine the methods of 13C- and 1H-NMR and broadband dielectric spectroscopy to probe liquid crystalline order and molecular mobility. We find that the dynamics of mesogenic molecules (5CB) in the free volume of nanoporous sol-gel glass (5 nm pore diameter) is as fast as in the free bulk phase. In addition, a boundary layer of molecules with reduced mobility covers the pore walls. Isotropic-nematic transition as well as crystallization of the confined nematogen are considerably suppressed. In order to extract the temperature dependence of the nematic order parameter from NMR data, a mathematical model is applied which describes the combined influences of orientational order and diffusional averaging in randomly oriented pores on NMR spectra of the nematogens. © 1997 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.473425
