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Measuring Material Microstructure Under Flow Using 1-2 Plane Flow-Small Angle Neutron Scattering
Published on: February 6, 2014
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Direct evidence for structural transition promoting shear thinning in cylindrical colloid assemblies.
Kazuhiro Shikinaka1, Keisuke Kaneda, Saori Mori
1Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16, Naka-cho, Koganei, Tokyo, 184-8588, Japan.
Small (Weinheim an Der Bergstrasse, Germany)
|February 28, 2014
Summary
This study reveals how stimuli-responsive hydrogels made from imogolite and dicarboxylic acid show thixotropy. Mechanical shock causes rapid structural changes, linking microscopic shifts to macroscopic gel behavior.
Area of Science:
- Materials Science
- Polymer Chemistry
- Rheology
Background:
- Stimuli-responsive hydrogels offer tunable properties for various applications.
- Thixotropy, a time-dependent shear thinning behavior, is crucial for hydrogel functionality.
- Understanding the structure-property relationship in hydrogels is essential for material design.
Purpose of the Study:
- To investigate the stimuli-responsive and thixotropic behavior of hydrogels formed from imogolite and dicarboxylic acid.
- To elucidate the relationship between microscopic structural changes and macroscopic thixotropic behavior.
- To characterize the hierarchical architecture of these novel hydrogels.
Main Methods:
- Preparation of hydrogels using imogolite (a rigid rod-like polyelectrolyte) and dicarboxylic acid.
- Application of mechanical shock to induce stimuli-responsiveness and thixotropy.
- Utilisation of advanced structural and rheological characterisation techniques.
- Analysis of shear thinning behavior in relation to structural transitions.
Main Results:
- The hydrogel demonstrated rapid thixotropy (seconds or sub-seconds) upon mechanical shock.
- A direct relationship between microscopic structural changes and macroscopic thixotropic behavior was established.
- The hydrogel possesses a hierarchical architecture: sheathed nanotubes and hydroclusters of cross-bridged nanotubes/frameworks.
- Gel/sol transition (thixotropy) originates from the formation/disintegration of the network structure, while hydroclusters remain intact.
Conclusions:
- The study provides the first direct evidence linking microscopic structural changes to macroscopic thixotropy in imogolite-based hydrogels.
- The hierarchical structure, specifically the network of imogolite and dicarboxylic acid, governs the observed thixotropic properties.
- These findings advance the understanding of stimuli-responsive materials and their potential applications.
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