I want to apply a chitosan solution to the surface of a dry film made from a mixture of PVA/PVP. I aim to fabricate a two-layer film consisting of a PVA/PVP film and a chitosan film. How can I do this? I dissolved PVA/PVP in deionized water and chitosan in acetic acid. However, when I apply the chitosan solution to the PVA/PVP film, the film dissolves and gets destroyed.