1 / 23

Emulsions and Microemulsions

Emulsions and Microemulsions. 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). Oil and Water do not mix !!. What we need for making macroemulsions ?.

dinh
Download Presentation

Emulsions and Microemulsions

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Emulsions and Microemulsions

  2. 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)

  3. Oil and Water do not mix !!

  4. 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

  5. Some special effects of surfactants • Decrease of surface tension • „Control“ of the type of emulsion • Droplet stabilization

  6. Decrease of surface tension • Decrease of the energy input !

  7. „Control“ of the type of emulsion • HLB - value (Hydrophilic-Lipophilic-Balance) • HLB = 20 M hydrophilic part / M total  For nonionic surfactants only !!

  8. Droplet stabilization • Electrostatic stabilization • Steric stabilization

  9. How one can come to small droplets ? • Macroemulsions (d > 1000nm) Mechanism of emulsification: - adsorption (increase of the surfactant concentration) - spreading

  10. How one can come to smaller droplets ? • 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“)

  11. Laplace pressure ( pLaplace) •  pLaplace = 2  / r  - surface tension r– radius of the droplet

  12. How one can come to muchsmaller droplets ? • Microemulsions ( 10 < d < 100 nm) - Thermodynamically stable dispersion of one liquid phase into another, stabilized by an interfacial film.

  13. 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)

  14. Microemulsions are thermodynamically stable !

  15. Ho – Spontaneous Curvature of the surfactant film • The most essential parameter of the system !!

  16. Microemulsions (ternary systems) • water, oil, surfactant

  17. Microemulsions (quaternary systems) • water, oil, surfactant and co-surfactant

  18. w/o - microemulsion + water soluble polymer Polymer induced cluster formation

  19. Polyelectrolyte-modified microemulsions • Oppositely charged PEL can be incorporated !! •  PEL increase the stability of the surfactant film !!

  20. Fields of application • Microemulsions as nanosize reactor • Microemulsions in separation processes • Microemulsions as drug delivery systems • Microemulsions in enhanced oil recovery

  21. Precipitation BaSO4 nanoparticle formation! Mix Microemulsion I and II Collision and coalescence of droplets w/o Microemulsion I w/o Microemulsion II containing e.g. 1mM BaCl2 containing e.g. 1mM Na2SO4

  22. Polyelectrolyte-modified microemulsions as nanoreactors ? • PEL can control the particle growing process ??? • PEL can stabilize nanoparticles during the process of redispersion ???

  23. Isolation of polymer-stabilized nanoparticles (patent: WO2004/056928AS) Nanoparticle formation in w/o microemulsions Solvent evaporation Redispersion of the polymer-stabilizied nanoparticles

More Related