Modification of the air-water interface by a chitosan adsorption process.: Effect on an amphiphilic polymer monolayer

Monolayer formation by poly[(maleic anhydride)-alt-(stearyl methacrylate)] (MA-alt-StM) on aqueous subphases, with and without chitosan, was studied by the Langmuir technique. Chitosan (CS) modified considerably the shape of the MA-alt-StM isotherms on water. To explain this behavior, the surface activity properties of chitosan at the air-solution interface were studied. The variations of the interfacial tension, gamma(int), with chitosan concentration and temperature, were also determined. The results were discussed in terms of the modification of the air-water interface owing to the presence of chitosan in the subphase and the surface activity. It was found that the standard free energy of adsorption, DeltaG(ads)(0),values were dependent on the degree of acetylation (DA) over the DA range being studied. (C) 2004 Society of Chemical Industry.