Engineers in the United States may have found a solution for replacing the microplastics used in paints, food and cosmetics. And the answer lies in a natural fibre known to all: silk.

Whether in our cosmetics, in our clothes or on our plates, microplastics are everywhere. In response to this growing pollution problem, American scientists from the prestigious Massachusetts Institute of Technology (MIT) have come up with an alternative that is surprisingly sourced from silkworms.

More precisely, the scientists have used silkworm cocoons. And their method could make it possible to obtain the same effects as those expected from microplastics, whether in terms of texture (smoother and more velvety for a cosmetic cream, for example) or for the protection of products such as foodstuffs.

"The EU has already declared that these added, nonbiodegradable microplastics must be eliminated by 2025, so the search is on for suitable replacements, which do not currently exist," the researchers explain in a statement.

This team of engineers has devised a biodegradable system based on silk to replace microplastics added to agricultural products, paints and cosmetics. The idea is simple: dissolve silkworm cocoons in water to obtain a texture similar to that of microplastics.

"By precisely adjusting the polymer chain arrangements of silk materials and addition of a surfactant, it is possible to fine-tune the properties of the resulting coatings once they dry out and harden," the scientists explain.

Recovering used silk fabric

Considered "safe" in the food and medical fields, silk is a biodegradable and non-toxic material for the body. It is also relatively easy to obtain as it can be extracted from the cocoons of silkworms or recovered from used silk fabric (or inferior-quality silk, unusable for textile manufacturing).

"While silkworm cocoons must be painstakingly unwound to produce the fine threads needed for fabric, for this use, non-textile-quality cocoons can be used," say the engineers, who conducted initial laboratory tests based on a standard water-soluble micro-encapsulated herbicide product tested on a corn crop.

While other similar experiments have been conducted before with biodegradable materials to replace microplastics, the MIT team insists that encapsulating high-content active substances is necessary to pave the way for commercial use.

"The only way to have an impact is where we can not only replace a synthetic polymer with a biodegradable counterpart, but also achieve performance that is the same, if not better," explains Benedetto Marelli, MIT professor of civil and environmental engineering. – AFP Relaxnews