PEC films prepared from chitosan-alginate coacervates

Chitosan-alginate polyelectrolyte complex (PEC) have been prepared in situ in beads and microspheres, This study examines the preparation of suitable chitosan-alginate coacervates for casting into homogeneous PEC films for po tential applications in packaging, controlled release systems and mound dre ssings. Coacervation between chitosan and alginate ass rapid, but the rate may be controlled with the addition of,vater miscible organic solvents. Com pared with ethanol and PEG200, acetone was the more promising solvent moder ator, Suspensions of fine, uniformly dispersed coacervates were produced by a dropwise addition of 0.25% w/v chitosan solution (solvent: 1:1 v/v of 2% acetic acid and acetone) into 0.25% w/v sodium alginate solution in water under rapid agitation. The PEC films were transparent and flexible. They ex hibited high permeability to water vapor, but resisted complete dissolution in 0.1 M HCl, distilled water and pH 7.4 phosphate buffer solution, Micros copic heterogeneity in the films could be reduced by immersion in aqueous m edia, but this was accompanied by modifications in the thickness, permeabil ity and mechanical property of the films.