AbstractsEngineering

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 agglomeration.