Rigid waterproof coating for paper aims to reduce our dependence on plastic

For the sake of spring and the environment, a significant amount of research is underway on reducing plastic for many and different applications. For the first time, researchers have found a way to provide relatively durable paper materials with some of the useful properties of plastics. This can be done easily, cost-effectively and efficiently. A coating called Choetsu not only makes waterproof paper but also retains its flexibility and breaks down safely as well.

It is difficult to get away from the fact that plastic materials are largely harmful to the environment. You have probably seen pictures of plastic pollutants washing up beaches, destroying rivers and killing countless animals. Still, the problem often seems to be completely out of our hands given that plastic materials are present in everyday life. Professor Zenji Hiroi from the Institute of Solid State Physics at the University of Tokyo and his team are exploring how materials science can help, and their latest discovery aims to replace certain uses of plastic with something more durable: paper.

“The biggest problem with plastic materials as I see it is their inability to degrade quickly and safely,” says Hiroi. “There are materials that can be degraded in a safe way, such as paper, but obviously paper can not meet the many uses that plastic can. But we have found a way to give paper some of the fine properties of plastic, but without any of the We call it Choetsu, an inexpensive biodegradable coating that provides waterproofness and strength to simple paper. “

Choetsu is a combination of materials that, when applied to paper, spontaneously generates a strong and waterproof film when it comes in contact with moisture in the air. The coating consists of safe and inexpensive chemicals, mostly methyltrimethoxysilane, a little isopropyl alcohol and a small amount of tetraisopropyl titanate. Paper structures, such as food containers, are sprayed with or dipped in this liquid mixture and dried at room temperature. When dry, a thin layer of silica containing methyl, a type of alcohol, forms on the cellulose that makes up the paper, giving it strong and waterproof properties.

In addition, reactions that take place during the coating procedure automatically create a layer of titanium dioxide nanoparticles. These give rise to a dirt and bacteria repellent property called photocatalytic activity, which protects the coated object for a long time. All chemicals involved in the coating degrade over time into harmless things such as coal, water and sand-like silicon.

“The technical challenge is clear, and some applications may be realized soon, such as the consumption, packaging or storage of food,” said Hiroi. “We now hope to be able to apply this approach to other types of materials as well. The liquid composition can be adapted to other materials, and we can create a dirt and mold resistant coating that can be formed on glass, ceramics and even other plastics to expand. “Together with researcher Yoko Iwamiya, who has been working in this field for some time now, and the rest of my team, I hope we can do something truly beneficial for the world.”

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Material provided by University of Tokyo. Note! The content can be edited for style and length.

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