Direct Evidence for Structural Transition Promoting Shear Thinning in Cylindrical Colloid Assemblies

In this paper, we describe stimuli‐responsive hydrogels prepared from a rigid rod‐like polyelectrolyte ‘imogolite’ and a dicarboxylic acid. The hydrogel exhibited thixotropy in response to mechanical shock within the order of seconds or sub‐seconds. Here, using the latest structural/rheological char...

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Bibliographic Details
Published in:Small (Weinheim an der Bergstrasse, Germany) Germany), 2014-05, Vol.10 (9), p.1813-1820
Main Authors: Shikinaka, Kazuhiro, Kaneda, Keisuke, Mori, Saori, Maki, Tei, Masunaga, Hiroyasu, Osada, Yoshihito, Shigehara, Kiyotaka
Format: Article
Language:English
Subjects:
colloids
Dicarboxylic acids
gels
Hydrogels
Mechanical shock
Nanotechnology
Nanotubes
Origins
phase transition
Polyelectrolytes
R&D
Research & development
self-assembly
Sol gel process
Thixotropy
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Summary:In this paper, we describe stimuli‐responsive hydrogels prepared from a rigid rod‐like polyelectrolyte ‘imogolite’ and a dicarboxylic acid. The hydrogel exhibited thixotropy in response to mechanical shock within the order of seconds or sub‐seconds. Here, using the latest structural/rheological characterisation techniques, the relationship between the structural transition processes and the shear thinning was estimated. The evidence obtained by the experiments revealed for the first time the direct relationship between the microscopic structural change and the macroscopic thixotropic behavior that have been extensively discussed. The thixotropic hydrogel has the hierarchical architecture in the combination of imogolite and dicarboxylic acid, i.e., sheathed nanotubes/hydroclusters of cross‐bridged nanotubes/frameworks. The formation and disintegration of the network structure upon resting and agitating, respectively, were the origin of gel/sol transition (thixotropy), although the hydroclusters of cross‐bridged nanotubes were maintained throughout the transition. A stimuli‐responsive hydrogel prepared from a rigid rod‐like polyelectrolyte ‘imogolite’ and a dicarboxylic acid is described. The hydrogel exhibits thixotropy in response to mechanical shock within the order of seconds or sub‐seconds. The structural origin of the thixotropy of the hydrogel consisted of cylindrical colloids as revealed from an estimation of dynamic structural transition on nano‐ to mesoscopic scale.
ISSN:1613-6810
1613-6829
DOI:10.1002/smll.201303360