Phase separation patterned films of natural materials: Preparation of mixed monolayers of nanocellulose integrates and organo‐modified nanoclays

Abstract Mixed monolayers of cellulose acetate and organo‐modified montmorillonite were prepared on a water surface, and their morphologies and structures were evaluated. Cellulose acetate exhibited an integrated morphology of cellulose nanofibers. A mixed monolayer of nanocellulose and organo‐modified montmorillonite was found to be a phase‐separated system in the surface pressure‐area isotherm analysis. The surface morphology of the mixed film formed a patterned surface in which clay nanoparticles and nanofibers coexisted. As the cellulose acetate ratio in the mixed film increased, the size of the clay nanoparticles decreased. The surface free energy of the mixed film was intermediate between those of the two components; however, it showed the most hydrophilic characteristic by being wettable by water. The layered structure of the mixed films showed a longer spacing value than that of the organo‐modified nanoclay film, indicating a change in orientation. In contrast, the in‐plane order was amorphous, and no improvement in periodicity or crystallinity was observed even after annealing. In addition, the clay part of the phase‐separated film exhibited selective molecular adsorption ability, and it was possible to form adsorbent patterns.