Viscosity of soft spherical micro-hydrogel suspensions
Heather M Shewan1, Jason R Stokes1
1School of Chemical Engineering, University of Queensland, Brisbane, QLD 4072, Australia.
Journal of Colloid and Interface Science
|December 19, 2014
Summary
The viscosity of microgel suspensions depends on particle size, not elasticity. Softer microgels show decreased volume at higher concentrations, deviating from hard sphere models. This study offers a new analysis method.
Area of Science:
- Rheology
- Soft Matter Physics
- Polymer Science
Background:
- Soft particle suspensions, like microgels, pose challenges due to solvent content and volume changes.
- Particle elasticity and physiochemical effects influence suspension rheology.
- Understanding microgel suspension behavior requires accounting for their unique properties.
Purpose of the Study:
- To investigate the effect of particle elasticity on microgel suspension viscosity.
- To compare microgel suspension viscosity to a hard sphere model.
- To develop a method for analyzing soft sphere suspension viscosity.
Main Methods:
- Utilized non-colloidal hydrogel spheres with varying elasticity.
- Compared suspension viscosity to a theoretical hard sphere model.
- Determined maximum packing fraction using random close packing from particle size distribution.
Main Results:
- Harder microgels followed the hard sphere model up to random close packing.
- Softer microgels deviated from the model at approximately 50% effective phase volume.
- This deviation indicates a decrease in specific volume with increasing phase volume for softer microgels.
Conclusions:
- Particle elasticity does not directly impact soft sphere suspension viscosity up to random close packing.
- Microgel volume reduction at high concentrations is due to incomplete re-swelling.
- A practical method for analyzing microgel and soft sphere suspension viscosity was presented.
Keywords:
Hydrogel particlesMaximum packing fractionMicrogelsPhase volumeRandom close packingSoft spheresSuspension rheologyMore Related Videos
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