Man made his first knife from stone. Later, the knives became metal, and until now the "authority" of metals in this area remains indisputable. As an exception, we can only mention the ceramic knives made of zirconium oxide.
However, as it turned out, having a basic knowledge of chemistry, you can even make a knife from foam, which was clearly shown by YouTube user kiwami japan.
To do this, he used several ingenious technologies for condensing air-filled polystyrene foam, a material for producing polystyrene foam.
First, he made orange peel puree, from which he then distilled orange oil. After that, with his help, he dissolved the polystyrene foam and treated the resulting substance with ethyl alcohol, finally removing air bubbles from it. The result is a fairly strong and solid workpiece for making a knife blade.
Judging by the video, the foam knife can cut and even keep the blade sharp for a while. However, it is unlikely to compete with any, even the simplest kitchen metal knife. And yet the main idea of the experiment is to show how even very unusual problems can be solved with the help of an understanding of chemistry and physics.