Preparation and characterization of chitosan based micro networks: Transposition to a prilling process

Beads of chitosan (CS) crosslinked network and of chitosan/poly(ethylene oxide) (CS/PEO) semi-interpenetrating network (semi-IPN) were prepared by a dropping technique and characterized. PEO content in the beads of semi-IPN was determined by gel permeation chromatography. CS crosslinking ratio was evaluated qualitatively by ATR-FTIR spectroscopy and quantitatively by UV spectrophotometry. After drying in a fluidized bed apparatus, a monodisperse population of well individualized, spherical, and smooth particles was obtained. It was shown that bead collapsus during the drying stage was avoided thanks to the chemical crosslinking of CS chains. By the prilling, or laminar jet break-up technology, production at a larger scale was also achieved. This process allowed the formation of a row of well calibrated drops of polymer solution under the influence of a vibration. Polymer solution characteristics, particularly viscosity, constituted a critical factor in the feasibility of the prilling process. Transposition of the formulation was managed through the optimization of process parameters such as vibration frequency, amplitude, and flow rate. (C) 2004 Wiley Periodicals, Inc.