Influence of key parameters on the morphology of ethylcellulose microcapsules prepared via room-temperature spray drying

Abstract

In this contribution, the morphology of ethylcellulose (EC) microspheres prepared with a room-temperature spray-drying technique is examined as a function of solution concentration, nozzle-totarget distance, and choice of solvent. Additionally, to determine the morphology of EC microspheres in the presence of an aqueous encapsulated material, a series of encapsulation measurements was conducted using hydrogen peroxide solution as the core component. It was observed that highly concentrated EC solutions lead to the formation of tail-like fibers adjacent to the sprayed microcapsules because of the high viscosity of solutions. Furthermore, when the solutions are sprayed from relatively short nozzle-to-target distances, porous EC films are formed on the target surface along with the EC microspheres. Three nozzle-to-target distances were tested (38, 69, and 115 cm), and the optimal one was found to be 115 cm. To determine how and to what extent the solvent used in room-temperature spraydrying experiments affects the morphology of resultant microspheres, EC was dissolved in either acetone or dichloromethane (DCM), and sprayed from the resultant solutions. While microcapsules prepared from the EC-in-DCM system exhibit even, but porous wall surfaces, microspheres prepared from the EC-in-acetone solution display irregular, but cavity-free wallsurfaces. Finally, as opposed to the pure EC capsules, the ones containing H 2 O 2 solution exhibit very smooth wall surfaces; this effect was attributed to the plasticizing effect that the aqueous solution has on the ethylcellulose macromolecules.

Biodegradable Polymeric Capsules Obtained via Room Temperature Spray Drying: Preparation and Characterization

“…The relatively high viscosity of the PHB-in-DCM solution subjected to shear through the spraying nozzle, coupled with the inability of polymeric chains to quickly crystallize and/ or vitrify, triggers the formation of PHB fibers along with the formation of microspheres. A similar formation of tail-like fibers was observed upon spraying ethylcellulose solutions of high viscosities [31]. The fiber formation mechanism is not entirely understood.…”

Comparative analysis of freeze drying and spray drying methods for encapsulation of chlorophyll with maltodextrin and whey protein isolate

“…Products dried by SD have important and very desirable properties such as better solubility, lower humidity and higher thermal stability ( Stefanescu, 2010 ) and this issue can be a reason for increasing the stability of SDM compared to FDM at higher temperatures. Both produced microcapsules showed significant thermal stability (p < 0.05) compared to free Chl.…”