Tunable gas barrier properties of filled-PCL film by forming percolating cellulose network

Herein, a three-dimensional percolating cellulose nanocrystal network has been successfully entangled into a poly(caprolactone) (PCL) film to prepare fully biodegradable bio-nanocomposites. To strongly assembly the reinforcing dense cellulose phase and PCL chains and limit the incompatibility effect, the cellulose surface was chemically modified using a long-chain isocyanate as grafting agent. Structural effects are highlighted through gas transport examination using several diffusing probes. A peculiar and unexpected behavior is evidenced: both permeability and diffusivity increased, whereas solubility is reduced, compared to the unfilled PCL film. One can suspect that the formation of the reinforcing cellulose network and its anchoring to PCL chains are the cause of structural defects facilitating the gas transfer localized in interfacial regions. The resulting structure of the film plays a main role on gas barrier performances compared to the change in crystallinity and tortuosity effect induced by rod-like nanoparticles.