In this work, uniform thin chitosan coatings were spin coated onto copolyester substrate. The use of high concentration acetic acid (50 wt.%) as the chitosan solvent increased the protonation of chitosan amino groups, allowing for greater interactions between the solution and the surface of the substrate. Further, surface oxidation was used to incorporate additional functional groups in the copolyester surface, facilitating solution/substrate interactions. The interfacial interactions between the chitosan solution and copolyester substrate were evaluated by the contact angle measurements.