Arcioni، نويسنده , , Alberto and Bacchiocchi، نويسنده , , Corrado and Vecchi، نويسنده , , Ilaria and Venditti، نويسنده , , Giampaolo and Zannoni، نويسنده , , Claudio، نويسنده ,
We report on a comparison between the random disorder effects of an hydrophobic (R812) or an hydrophilic (A380) aerosil on the order and dynamics of the 3β-DOXYL-5α-cholestane spin probe in the liquid crystal 4-n-pentyl-4′-cyanobiphenyl (5CB) using the ESR technique. Increasing the aerosil concentration up to 3 wt% the probe order parameter is depressed with a larger effect for the hydrophilic aerosil. The dynamics in the isotropic phase is of Arrhenius type and essentially concentration and aerosil-type independent. Deviations from this behavior are observed in the nematic even at 0.3 wt% of hydrophilic aerosil and are well represented by a Vogel–Fulcher–Tammann type law, suggesting that a glass-like state can be induced by a very small amount of random disorder.