Food packaging is an important component of our modern life, ensuring a longer life for products — which comes with a lot of benefits, including environmental benefits. However, metalized coatings for food packaging feature several layers of different material, which makes it very difficult to recycle them. Creating versions that are recyclable is also quite challenging.
“The production of scalable, environmentally friendly, non-toxic, high aspect ratio two-dimensional nanosheet coating to produce oxygen barrier food packaging film is an unsolved major challenge,” the researchers write.
Food packaging films are in contact with food, which puts very specific limits on their chemical composition: it needs to be something that doesn’t interact with the food and ensures that it doesn’t spoil or come in contact with molecules from the air. It also needs to be a drop-in solution for existing coating technologies, and lastly, it must also be cost-effective compared to the current practice of aluminium vaporization, which is most commonly employed in the industry.
With this objective in mind, the team set out to design and produce a recyclable film that not only works but can also be applied at a large scale with decent costs.
Composite materials are always hard to recycle, and in this particular case, the plastic and aluminum foil first need to be separated and recycled, a process which is difficult and inefficient.
In the new material, the plastic-aluminum film was replaced by a set of nanosheets of layered double hydroxides (a fully inorganic and unreactive material).
The process to produce these sheets is cheap and requires only water and amino acids. The resulting film is transparent, equally impermeable to oxygen and water vapor, and quite sturdy. Since the production process is fully synthetic, different parameters can be controlled, for instance, to add even more safety and protection in the case of delicate foods.
Most importantly, researchers say, these coated films are also transparent and mechanically robust, making them suitable for flexible food packaging while also offering new recycling opportunities. It’s the kind of technology and approach we need to tackle our plastic problem before it goes completely out of control.