Download - Macro and Micro Emulsion
-
8/10/2019 Macro and Micro Emulsion
1/23
Emulsions and Microemulsions
-
8/10/2019 Macro and Micro Emulsion
2/23
Emulsion:
A dispersion of droplets of one liquid
in another, immiscible liquid
Macroemulsions (d > 1000 nm)
Miniemulsions (100 nm < d < 1000 nm)
Microemulsions ( 10 nm < d < 100 nm)
-
8/10/2019 Macro and Micro Emulsion
3/23
Oil and Water do not mix !!
-
8/10/2019 Macro and Micro Emulsion
4/23
What we need for making
macroemulsions ?
Emulsifier: May make it easier to form a
macroemulsion and provide stability against
aggregation, e.g. surfactants or polymers
-
8/10/2019 Macro and Micro Emulsion
5/23
Some special effects of
surfactants
Decrease of surface tension
Control of the type of emulsion
Droplet stabilization
-
8/10/2019 Macro and Micro Emulsion
6/23
Decrease of surface tension
Decrease of the energy input !
-
8/10/2019 Macro and Micro Emulsion
7/23
Control of the type of emulsion
HLB- value
(Hydrophilic-Lipophilic-Balance)
HLB= 20 M hydrophilic part/ M total
For nonionic sur factants only !!
-
8/10/2019 Macro and Micro Emulsion
8/23
Droplet stabilization
Electrostatic stabilization
Steric stabilization
-
8/10/2019 Macro and Micro Emulsion
9/23
How one can come to smalldroplets ?
Macroemulsions (d > 1000nm)
Mechanism of emulsification:
- adsorption
(increase of the surfactant concentration)
- spreading
-
8/10/2019 Macro and Micro Emulsion
10/23
How one can come to smallerdroplets ?
Miniemulsions (100 nm < d < 1000nm)
- increase of the surfactant concentration
- increase of the energy input !!
(e.g. ultrasound treatment)
- addition of hydrophobic agents
(supress of Ostwald ripening)
-
8/10/2019 Macro and Micro Emulsion
11/23
Laplace pressure (pLaplace)
pLaplace = 2 / r
- surface tension
r
radius of the droplet
-
8/10/2019 Macro and Micro Emulsion
12/23
How one can come to muchsmallerdroplets ?
Microemulsions ( 10 < d < 100 nm)
- Thermodynamically stabledispersion of
one liquid phase into another, stabilizedby an interfacial film.
-
8/10/2019 Macro and Micro Emulsion
13/23
Microemulsions
Isotropic, optically clear
Thermodynamically stable
Newtonian-flow behaviour Low surface tension
Reversible temperature behaviour
Droplet size between 10 and 100 nm(o/w ; w/o ; bicontinuous)
-
8/10/2019 Macro and Micro Emulsion
14/23
Microemulsions are
thermodynamically stable !
-
8/10/2019 Macro and Micro Emulsion
15/23
HoSpontaneous Curvature
of the surfactant film
The most essential parameter
of the system !!
-
8/10/2019 Macro and Micro Emulsion
16/23
Microemulsions
(ternary systems)
water, oil, surfactant
-
8/10/2019 Macro and Micro Emulsion
17/23
Microemulsions
(quaternary systems)
water, oil, surfactantand co-surfactant
-
8/10/2019 Macro and Micro Emulsion
18/23
w/o - microemulsion + water soluble polymer
Polymer induced cluster formation
-
8/10/2019 Macro and Micro Emulsion
19/23
Polyelectrolyte-modified microemulsions
Oppositely
charged PEL can
be incorporated !!
PEL increase the
stability of thesurfactant film !!
-
8/10/2019 Macro and Micro Emulsion
20/23
Fields of application
Microemulsions as nanosize reactor
Microemulsions in separation processes
Microemulsions as drug delivery systems
Microemulsions in enhanced oil recovery
-
8/10/2019 Macro and Micro Emulsion
21/23
-
8/10/2019 Macro and Micro Emulsion
22/23
Polyelectrolyte-modified microemulsions
as nanoreactors ?
PEL can control the
particle growing
process ???
PEL can stabilize
nanoparticles
during the processof redispersion ???
-
8/10/2019 Macro and Micro Emulsion
23/23
Iso lat ion of po lymer-stabi l ized nanopart ic les
(patent: WO2004/056928AS)
Nanoparticle formation in w/o microemulsions
Solvent evaporation
Redispersion of the polymer-stabiliziednanoparticles