Green Environment: Super Environmentally Friendly Plastics That Can Be Decomposed By Bacteria Are The Commercial Potential Of New Materials

Billions of tons of plastic waste fill our planet. Most of them accumulate on land, sink into the sea, or decompose into tiny particles, namely microplastics, which pollute the air and water, and infiltrate into plants, human and animal blood. The threat posed by plastics is increasing every year, because they are composed of a large number of molecules, which are called polymers and are resistant to biodegradation. At present, biodegradable plastics account for less than one fifth of the total plastic production, and the process required to decompose them is still relatively cumbersome. 　

In a study published on ACS Nano, Dr. Angelica Niazov Elkan from the Department of Molecular Chemistry and Materials Science of Weizmann Institute of Science Haim Dr. Weissman and Boris Professor Rybtchinski has created a new composite plastic that can be easily degraded by bacteria. This new material is produced by combining biodegradable polymers with the crystals of biological substances. It has three advantages: cheap, easy to prepare and very solid. The deceased was also involved in the study Dr. Eyal Shimoni, Dr. XiaoMeng Sui, Dr. Yishay Feldman and Professor H. Daniel Wagner.

At present, many industries are actively adopting composite plastics, which are composed of two or more pure materials, and have various beneficial characteristics such as portability, high strength, etc. These plastics are now used to manufacture key components of various industrial products, from aircraft, cars to bicycles.

In order to create a composite plastic that can meet the needs of industry and is environmentally friendly, Weizmann's researchers decided to focus on ordinary, inexpensive raw materials whose performance can be improved. They found that tyrosine molecule (a ubiquitous amino acid, which can form very solid nanocrystals) can be used as an effective component of biodegradable composite plastics. After studying how tyrosine combines with several polymers, they chose hydroxyethyl cellulose, a cellulose derivative, which is widely used in the manufacture of drugs and cosmetics.

Hydroxyethyl cellulose itself is a weak material that is easy to decompose. In order to combine it with tyrosine, the two materials were mixed in boiling water. When they are cooled and dried, a very strong composite plastic is formed, which is made of fibrous tyrosine nanocrystals. These nanocrystals grow into hydroxyethyl cellulose and combine with it. In an experiment to reveal the strength of new plastics, 0.04 Mm thick material strips can withstand a load of 6 kg.

In addition, the team found that this new material has several other unique characteristics, making it more useful in industry. Usually, when a material is strengthened, it loses its plasticity.

However, in addition to being very strong, this new composite plastic is more malleable (plastic) than its core component, hydroxyethyl cellulose. In other words, the combination of these two materials produces a synergistic effect, which is reflected in the emergence of extraordinary properties, so it has great industrial potential.

Because cellulose and tyrosine (whose crystals can be found in various types of hard cheese) are edible, this biodegradable composite plastic can actually be eaten. Is it delicious, too? We will have to wait to know that because the production process in the laboratory is not hygienic enough for food, researchers have not yet tried.

　　Rybtchinski Concluding: "The follow-up research we have started can improve the commercial potential of this new material, because we have replaced boiling in water with melting, which is more common in industry. This means that we need to heat biodegradable polymers until they become liquid, and then mix them with tyrosine or other suitable materials. If we can overcome the scientific and technological challenges in this process, we will be able to explore the possibility of producing this new composite plastic on an industrial scale. "