Joachim Koetz, Universität Potsdam

• Elexier of life ?
• potable gold-solution (aurum potabile)

Graham
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Colloids are glue-like substances, diffuse very slowly, and do not dialyse

W. Ostwald
Disperse systems suspensions
> 1000 nm colloidal dispersions
1 bis 1000 nm solutions
< 1 nm

Definition
Any particle that has some linear dimension between 1 nm and
1 μm is considered a colloid!
However, the limits are rather arbitrary.

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A state of subdivision in which the particles, droplets, or bubbles dispersed in another phase have at least one dimension between
1 – 1000 nm
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All combinations are possible between gas, liquid, and solid
W. Ostwald

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1927 Burry, Ekwall: Associating Colloids
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1929 Staudinger: Macromolecules

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Amphiphilic self-organizing systems
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Colloids are associated physically, not chemically
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Size and shape of the associates can change

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Any macromolecule consisting of
10
3 up to 10
9 atoms
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Any dispersed macromolecular coil having colloidal dimensions

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1923 Svedberg: Ultracentrifugation
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1932 Ruska: Electron Microscopy

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One dimension between 1 and 1000 nm
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All combinations of dispersed matter
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Classification: - colloidal dispersions
- associating colloids
- macromolecules

Inorganic component
Organic component
SiO
2
*
Aragonite,
CaCO
3 x H
2
O
Hydroxyapatit,
Ca
10
(PO
4
)
6
(OH)
2 composite of hydrocarbon and protein composite of hydrocarbon and protein composite of collagenfilament and protein
Organism
Diatomeen
Perl oyster
Bone and teeth

Nanoparticles as Quantendots
• Color effects in glases
(e.g. CdS or gold)
• Non linear optical effects
(fast optoelectronical switches)
• High storage capacity
(optical storage)

Formation of Nanoparticles
(Nanotechnology)
• Particle formation from gas phases
• Particle formation from droplets
• Particle formation from Sol-Gel-Processes

Nanoparticles produced by nucleation processes
• Colloidal Sulfur
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Colloidal Gold
• Latex Particles
• Nanocrystallites

Conditions for the production of monodisperse nanoparticles
- Heterogeneous nucleation
- La Mer diagram

Disciplines and Topics for which Colloids and colloidal phenomena are important
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Analytical chemistry
Physical chemistry
Biochemistry
Material Science
Petroleum Science
Household products
Imaging technology
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Adsorption phenomena, chromatography
Nucleation, supersaturation, liquid crystals
Electrophoresis, osmosis, ultrafiltration
Ceramics, fibres, powder metallurgy
Oil recovery,
Milk, beer, cosmetics
Emulsions, printing inks, paper coating