Plastic substitute made from salmon sperm is here, which can be recycled by water

We are more or less aware of the hazards caused by plastics. Most of them are made of petrochemical products. They are disposable and rarely recycled. They either need centuries to decompose, or are incinerated or sent to landfills.

▲ Picture from: Pixabay

Scientists have conducted a lot of research to find plastic substitutes that are less harmful to the natural environment. A team of scientists from Tianjin University focused on an unlikely raw material-salmon sperm. Related papers were published in the Journal of the American Chemical Society on November 14.

The research team dissolves DNA strands from salmon sperm in water and mixes them with biomass-derived ionomers to form a soft, malleable material "hydrogel" (hydrogel), which can be made into different The three-dimensional shape will solidify after freeze-drying. The final product is a material similar to plastic, which is called "DNA plastic" by the team.

Researchers have used this environmentally friendly material to make a cup, a puzzle and a DNA model.

Although the raw material was obtained from salmon sperm this time, the DNA, which carries the genetic code of all living things on the earth, is the real source.

A 2015 study estimated that there are approximately 50 billion tons of DNA on earth. In theory, we can use other sustainable sources to make "DNA plastic" in a similar way, such as waste from crops, algae, or bacteria, rather than just salmon sperm.

The more important question is, will "DNA plastic" be better than other alternatives?

▲ Picture from: ACS

The research team pointed out that it is more environmentally sustainable than all existing types of plastics. This sustainability involves all aspects of production, use, and scrap.

In the production process, raw materials are derived from bio-renewable resources; the water treatment strategy is environmentally friendly, does not involve high energy consumption, does not use organic solvents, and does not produce by-products; Carbon emissions have been reduced by 97%.

The recycling of "DNA plastic" is also easier. If the articles made from it are immersed in water, the hydrogel will be obtained again, which can be remade into new articles and prolong the service life.

If it is no longer needed, it can be broken down by DNA digestive enzymes; while other environmentally friendly plastics, such as biodegradable plastics made from materials such as corn starch and algae, require a lot of energy to manufacture and are difficult to recycle.

But on the other hand, the new material also has limitations-it can be easily recycled by water, which means it needs to be kept dry. If you add a waterproof coating, it will make recycling more difficult, which goes against the original intention. Therefore, it is suitable for electronic products and certain forms of packaging.

In addition, the research team pointed out that mass production of "DNA plastic" is still challenging, but not impossible. They stated in the paper: "This work provides a solution to convert bio-based hydrogels into bioplastics and demonstrates the closed-loop recycling of DNA plastics, which will promote the development of sustainable materials."

▲ Reference materials:
1.https://www.vice.com/en/article/3abb7w/salmon-sperm-plastic-cup-bioplastics
2.https://pubs.acs.org/doi/full/10.1021/jacs.1c08888
3.https://www.euronews.com/green/2021/11/29/sperm-is-being-used-to-create-an-eco-friendly-alternative-to-plastic

▲ The picture of the title comes from: vice

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