Was sind Kolloide ? - Universität Potsdam

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Introduction to Colloidal systems

Joachim Koetz, Universität Potsdam

Alchemist

• Elexier of life ?

• potable gold-solution (aurum potabile)

Definition (

Graham

)

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

Types of disperse systems

(

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.

Definition:

A state of subdivision in which the particles, droplets, or bubbles dispersed in another phase have at least one dimension between

1 – 1000 nm

All combinations are possible between gas, liquid, and solid

W. Ostwald

History of Colloid Chemistry

1927 Burry, Ekwall: Associating Colloids

1929 Staudinger: Macromolecules

Associating Colloids

Amphiphilic self-organizing systems

Colloids are associated physically, not chemically

Size and shape of the associates can change

Macromolecules as colloidal systems

Any macromolecule consisting of

10

3 up to 10

9 atoms

Any dispersed macromolecular coil having colloidal dimensions

History of Colloid Chemistry

1923 Svedberg: Ultracentrifugation

1932 Ruska: Electron Microscopy

The Colloidal Domain

One dimension between 1 and 1000 nm

All combinations of dispersed matter

Classification: - colloidal dispersions

- associating colloids

- macromolecules

Biomineralization

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

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

Analytical chemistry

Physical chemistry

Biochemistry

Material Science

Petroleum Science

Household products

Imaging technology

Adsorption phenomena, chromatography

Nucleation, supersaturation, liquid crystals

Electrophoresis, osmosis, ultrafiltration

Ceramics, fibres, powder metallurgy

Oil recovery,

Milk, beer, cosmetics

Emulsions, printing inks, paper coating

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