Time-dependent phase behavior of 5CB-DDAB-water microemulsions monitored by means of dielectric spectroscopy

Chen, Zhen and Nozaki, Ryusuke (2011) Time-dependent phase behavior of 5CB-DDAB-water microemulsions monitored by means of dielectric spectroscopy. Physical Review E - Statistical, Nonlinear, and Soft Matter Physics, 84 1: 011401.1-011401.9. doi:10.1103/PhysRevE.84.011401

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Author Chen, Zhen
Nozaki, Ryusuke
Title Time-dependent phase behavior of 5CB-DDAB-water microemulsions monitored by means of dielectric spectroscopy
Journal name Physical Review E - Statistical, Nonlinear, and Soft Matter Physics   Check publisher's open access policy
ISSN 1539-3755
1550-2376
Publication date 2011-07
Sub-type Article (original research)
DOI 10.1103/PhysRevE.84.011401
Open Access Status File (Publisher version)
Volume 84
Issue 1
Start page 011401.1
End page 011401.9
Total pages 9
Place of publication College Park, MD United States
Publisher American Physical Society
Collection year 2011
Language eng
Formatted abstract
The phase behavior of an inverse microemulsion composed of 4-cyano-4-n-pentylbiphenyl (5CB), didodecyl dimethyl ammonium bromide, and water was intensively studied recently, but controversy still remains on the existence of a "transparent nematic" (TN) phase. Previously, we studied the temperature-dependent dielectric behavior of this microemulsion. The results suggested that a superstructure composed of water droplets and confined 5CB molecules exists in the coexistence phase region, which may correspond to the notion of a TN phase. In this study, the time-dependent dielectric behaviors of this microemulsion in the isotropic, coexistence, and supercooled phase regions were investigated. In the coexistence and supercooled phase regions, the dielectric behaviors showed strong dependence on time, due to the hysteresis of phase transition and the upward diffusion of the water-droplet-rich isotropic phase. After the isotropic phase has been totally excluded out of the effective measurement area, the slow process was still observed in these two phase regions, which suggests that water droplets can stably exist in the liquid crystalline phase. A local microscopic phase evolution was observed in the coexistence phase region, which is similar to the temperature-induced phase evolution previously proposed by us. The dielectric behavior of the slow process during the phase evolution also suggests the existence of the superstructure. In addition, the mechanism of the slow process in different phase regions proposed in our previous study is also confirmed.
Keyword Ammonium compounds
Microemulsions
Liquid crystalline phase
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Civil Engineering Publications
 
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Created: Thu, 21 Mar 2013, 12:10:29 EST by Zhen Chen on behalf of School of Civil Engineering