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Coating fine particles
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
2014 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

Controlled release of an active is used in many

applications. An example is drug delivery were it is

desirable to release the active substance close to the

target. In paints can anti-mold substances be

encapsulated and released slowly during a long time

which can extend the lifetime of the paint. This work

investigated a coating process of loaded particles with

as low leakage of the active substance as possible. It

was also studied if the coating process was scalable.

The particles in use were porous silica that was coated

with sodium dodecyl sulphate (SDS), polyethyleneimine

(PEI) and tetraethyl orthosilicate (TEOS). To fill

particles, the active was dissolved in a solution and the

particles were added. The active adsorbed into the

pores of the particle. The coating principle was about

the same for all layers. The coating molecules were

dissolved in a solvent and the particles were added

during stirring. After centrifugation the coated

particles were separated from the solvent and left to

dry. The thermogravimetric analyzer (TGA) was used to

calculate the amount of adsorbed polymers on the

particle surface. UV/VIS spectrometer analyzed the

release rate of the active.

As the recipe was optimized, SDS could be excluded

from the process. An adsorption isotherm for PEI on

the particle surface showed that 0.5 g PEI/ g particle

the ratio required for covering the surface completely.

It was proved that if the active was dissolved in all

coating solutions during the coating, less leakage

appear and makes the coating process more

controlled. A higher amount of both PEI and TEOS

improves the encapsulation of the active, which

reduces the release rate. The coating process is proved

to be scalable as the particle concentration is

increased from 4.72 % to 16.5 % without too much


Place, publisher, year, edition, pages
2014. , 33 p.
UPTEC K, ISSN 1650-8297 ; 14009
National Category
Engineering and Technology
URN: urn:nbn:se:uu:diva-235233OAI: diva2:759456
External cooperation
SP, Sveriges tekniska forskningsinstitut
Educational program
Master Programme in Chemical Engineering
Available from: 2014-11-28 Created: 2014-10-30 Last updated: 2014-11-28Bibliographically approved

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