Novel nanostructured microfibrillated cellulose-hydroxypropyl methylcellulose films with large one-dimensional swelling and tunable permeability

► Microfibrillated cellulose and hydroxypropyl methylcellulose combine into layered films. ► Surprising decrease in permeability with increasing water-soluble polymer. ► Tuneable permeability similar to conventional controlled release films. ► Superabsorbent close to one-dimensional swelling.