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

Microfibrillated cellulose (MFC) films containing the water soluble and pharmaceutically approved polymer hydroxypropyl methylcellulose (HPMC) exhibited an unexpected decrease in permeability and excellent one-dimensional swelling properties above a threshold in HPMC content. It is proposed that the observed material characteristics derive from the influence of HPMC on the aggregation behavior of MFC in such a way that above a critical HPMC content the films are created through self assembly into a layered structure, composed of low swelling layers with swellable inter layer regions. The suggested structures were supported by high resolution microscopy. The findings should hold potential for direct applications, but even more as a concept for future material design.