Synthesis and Characterization of Ethyl Cellulose Microcapsules Containing Model Active Ingredients

Abstract

SummaryPolymers have a wide range of applications, including controlled drug release. In this paper, the methodology to produce microcapsules containing limonene and vanillin as model active ingredients is reported. Polymeric solutions composed by ethyl acetate as solvent, ethyl cellulose as the polymer and an active ingredient were prepared. The microcapsules were produced by dropping the polymeric solution on a coagulation bath, composed by water, sodium dodecyl sulfate, and acetic acid in different concentrations. The variation in concentrations was set to configurate coagulation baths with a wide range of surface tensions. According to the surface tensions, and through Scanning Electron Microscopy (SEM), different structures were observed: spongeous particles, polymeric dense rings or spherical microcapsules. The microparticles obtained had an average diameter of 30 µm. Selected structures were characterized internally by using SEM and Focused Ion Beam (FIB) in a Dual Beam Microscope. The external surface of the spherical particles was mostly dense, with observed nanopores, while micropores were distributed all along the inner structure, probably containing the active ingredient. The artifacts produced during characterization by FIB, as well the thermodynamics of the microcapsules formation are also discussed.