Wc 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 3 beta-DOXYL-5 alpha -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.
A comparison of the effects of dispersed hydrophobic or hydrophilic aerosil nanoparticles on the order and dynamics of the 5CB liquid crystal / A. ARCIONI; C. BACCHIOCCHI; I. VECCHI; G. VENDITTI; C. ZANNONI. - In: CHEMICAL PHYSICS LETTERS. - ISSN 0009-2614. - STAMPA. - 396:(2004), pp. 433-441. [10.1016/j.cplett.2004.08.081]
A comparison of the effects of dispersed hydrophobic or hydrophilic aerosil nanoparticles on the order and dynamics of the 5CB liquid crystal
ARCIONI, ALBERTO;BACCHIOCCHI, CORRADO;VECCHI, ILARIA;ZANNONI, CLAUDIO
2004
Abstract
Wc 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 3 beta-DOXYL-5 alpha -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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.