Spontaneous delamination of affordable natural vermiculite as a high barrier filler for biodegradable food packaging

Expensive biodegradable packaging as a preventative measure against continued accumulation of plastic waste in our environment is often in conflict with the need for high performing packaging materials that prevent food waste. Compounding with delaminated vermiculite nanosheets is a compelling concept to simultaneously improve barrier properties through creation of a ‘tortuous path’ while also decreasing the price of the system due to its natural abundance. However, an effective delamination process that captures the full barrier improvement potential of this natural filler has been lacking. Here, we present a superior protocol for vermiculite delamination based on reducing the intrinsic hydrophobicity due to interlayer Mg²⁺ cations and the transfer of this osmotically swollen, liquid crystalline state into organic solvents. Nanocomposite coatings of degradable polyesters on nanocellulose exhibited oxygen and water transmission rates of 1.30 cm³ m⁻² day⁻¹ atm⁻¹ and 1.74 g m⁻² day⁻¹, respectively, which competes with high-end, non-degradable poly(vinylidene dichloride) films.