Limits...
Direct Visualization of the Hydration Layer on Alumina Nanoparticles with the Fluid Cell STEM in situ.

Firlar E, Çınar S, Kashyap S, Akinc M, Prozorov T - Sci Rep (2015)

Bottom Line: Unusually high viscosities observed for suspensions of nanoparticles compared to those of micron size powders cannot be explained by current viscosity models.We observe the hydration layer formed over the particle aggregates and show that such hydrated aggregates constitute new particle assemblies and affect the flow behavior of the suspensions.We discuss how these hydrated nanoclusters alter the effective solid content and the viscosity of nanostructured suspensions.

View Article: PubMed Central - PubMed

Affiliation: Division of Materials Science and Engineering, US DOE Ames Laboratory, Ames, IA, 50011, USA.

ABSTRACT
Rheological behavior of aqueous suspensions containing nanometer-sized powders is of relevance to many branches of industry. Unusually high viscosities observed for suspensions of nanoparticles compared to those of micron size powders cannot be explained by current viscosity models. Formation of so-called hydration layer on alumina nanoparticles in water was hypothesized, but never observed experimentally. We report here on the direct visualization of aqueous suspensions of alumina with the fluid cell in situ. We observe the hydration layer formed over the particle aggregates and show that such hydrated aggregates constitute new particle assemblies and affect the flow behavior of the suspensions. We discuss how these hydrated nanoclusters alter the effective solid content and the viscosity of nanostructured suspensions. Our findings elucidate the source of high viscosity observed for nanoparticle suspensions and are of direct relevance to many industrial sectors including materials, food, cosmetics, pharmaceutical among others employing colloidal slurries with nanometer-scale particles.

No MeSH data available.


Related in: MedlinePlus

Cryo-HAADF-STEM image of diluted aqueous alumina slurry.The hydration layer is manifested as a faint cloud covering the aggregated nanoparticles. Scale bar: 100 nm. Inset shows the schematics of the hydrated aggregate.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4440531&req=5

f4: Cryo-HAADF-STEM image of diluted aqueous alumina slurry.The hydration layer is manifested as a faint cloud covering the aggregated nanoparticles. Scale bar: 100 nm. Inset shows the schematics of the hydrated aggregate.

Mentions: Figure 4 shows the cryo-HAADF-STEM image of the hydrated alumina sample. The hydration layer formed around the aggregated particles, manifested as a lighter shadow, is schematically shown in the inset.


Direct Visualization of the Hydration Layer on Alumina Nanoparticles with the Fluid Cell STEM in situ.

Firlar E, Çınar S, Kashyap S, Akinc M, Prozorov T - Sci Rep (2015)

Cryo-HAADF-STEM image of diluted aqueous alumina slurry.The hydration layer is manifested as a faint cloud covering the aggregated nanoparticles. Scale bar: 100 nm. Inset shows the schematics of the hydrated aggregate.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4440531&req=5

f4: Cryo-HAADF-STEM image of diluted aqueous alumina slurry.The hydration layer is manifested as a faint cloud covering the aggregated nanoparticles. Scale bar: 100 nm. Inset shows the schematics of the hydrated aggregate.
Mentions: Figure 4 shows the cryo-HAADF-STEM image of the hydrated alumina sample. The hydration layer formed around the aggregated particles, manifested as a lighter shadow, is schematically shown in the inset.

Bottom Line: Unusually high viscosities observed for suspensions of nanoparticles compared to those of micron size powders cannot be explained by current viscosity models.We observe the hydration layer formed over the particle aggregates and show that such hydrated aggregates constitute new particle assemblies and affect the flow behavior of the suspensions.We discuss how these hydrated nanoclusters alter the effective solid content and the viscosity of nanostructured suspensions.

View Article: PubMed Central - PubMed

Affiliation: Division of Materials Science and Engineering, US DOE Ames Laboratory, Ames, IA, 50011, USA.

ABSTRACT
Rheological behavior of aqueous suspensions containing nanometer-sized powders is of relevance to many branches of industry. Unusually high viscosities observed for suspensions of nanoparticles compared to those of micron size powders cannot be explained by current viscosity models. Formation of so-called hydration layer on alumina nanoparticles in water was hypothesized, but never observed experimentally. We report here on the direct visualization of aqueous suspensions of alumina with the fluid cell in situ. We observe the hydration layer formed over the particle aggregates and show that such hydrated aggregates constitute new particle assemblies and affect the flow behavior of the suspensions. We discuss how these hydrated nanoclusters alter the effective solid content and the viscosity of nanostructured suspensions. Our findings elucidate the source of high viscosity observed for nanoparticle suspensions and are of direct relevance to many industrial sectors including materials, food, cosmetics, pharmaceutical among others employing colloidal slurries with nanometer-scale particles.

No MeSH data available.


Related in: MedlinePlus