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EnglishWe report on a comparison between the random disorder effects of an hydrophobic (R812) or an hydrophilic (A38O) aerosil on the order and dynamics of the 3/3-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 con¬centration 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.
| Titolo: | Glass-like behavior at molecular level induced in a nematic by a dispersion of aerosil nanoparticles |
| Autore/i: | ARCIONI, ALBERTO; BACCHIOCCHI, CORRADO; VECCHI, ILARIA; ZANNONI, CLAUDIO |
| Autore/i Unibo: | |
| Anno: | 2005 |
| Rivista: | |
| Digital Object Identifier (DOI): | http://dx.doi.org/10.1080/15421400590930953 |
| Abstract: | We report on a comparison between the random disorder effects of an hydrophobic (R812) or an hydrophilic (A38O) aerosil on the order and dynamics of the 3/3-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 con¬centration 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. |
| Data prodotto definitivo in UGOV: | 2005-10-08 00:30:53 |
| Appare nelle tipologie: | 1.01 Articolo in rivista |
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http://hdl.handle.net/11585/5865
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