I am doing research in orthopedic surgery that involves using chitosan to make soft-tissue scaffolds. I am a third year chemical engineering student, and I understand everything I am doing except how chitosan can liquefy when an acid is added and solidify when a base is added. Does anyone know the changes the chemical structure undergoes when either an acid/base is added? I have to give a presentation next week and I'm not sure how to address this point. Thanks!