Chitosan-lipid films: microstructure and surface energy

Composite films of chitosan-laurate were shown to have low water permeability, while films containing other fatty acids or esters were not effective in this respect. Electron microscopy revealed the microstructure of these films to be very different, in terms of density, pore formation, channeling, surface contour, and packing pattern. The surface energy of the films was estimated, and the dispersion force component (gamma(s)d) and the polar component (gamma(s)p) were calculated. The chitosan-laurate film exhibited higher surface energy, but no variation on either surface, while all other films tested differed in both surface energy components depending on the surface orientation. In general, these physical attributes can be correlated quite well with the permeability characteristics of the particular film. It is postulated that the unique properties of the chitosan-laurate film could suggest the importance of the morphological arrangement of the lipid within the chitosan matrix.