Refresh your cognition! Chinese researchers create the first "never-melting ice and snow"

The 2022 Beijing Winter Olympics has opened, and the popularity of ice and snow sports continues to rise. The vision of "300 million people on ice and snow" proposed by my country has become a reality.

To promote ice and snow sports, ice is needed. However, ice and snow in the natural state will melt when the temperature rises, and water will drip, which is annoying. To build an ice rink artificially, it is necessary to build a drainage system, a gravel foundation, a heated cement layer, etc. The process is complicated, the mobility is poor, and the cost is high.

Professor Zhang Kai's team from the School of Aeronautics and Astronautics at Beijing Institute of Technology has developed a new type of material - gel ice snow. Its biggest feature is that it "never melts".

Recently, at the China Science and Technology Museum, the gel ice and snow board prepared by Zhang Kai's team was unveiled at the "Technology Winter Olympics" theme exhibition. The booth was not large, but it attracted many passers-by. Out of curiosity, everyone reached out to touch it. Children especially liked it, half of their bodies jumped on it, shouting: "It's cool, cool, and slippery! This is ice!"

More than 90% of gel ice and snow is water, so it has almost the same look and feel as natural ice and snow.

In fact, gel ice and snow at room temperature is a hydrogel material. It feels similar to jelly, but has better mechanical properties. If you poke it with your hand, you can see that its surface sinks a little and then bounces back immediately. You can press it, pull it, and roll it up - just like rolling up a blanket.

The secret of not melting lies in a hydrophilic polymer network. The design and preparation of this network are very particular. It is formed by polymerization reaction of various materials through chemical means. Depending on the needs, the materials, shapes and cross-linking methods of the polymer network are also different. When there is no polymer network, the ice crystals will melt into water after heating; but after adding the polymer network, the melted water is also firmly locked in the grid and cannot escape. In this way, even if the temperature rises, the hydrogel can still maintain the integrity of its shape - it is between liquid and solid. In fact, the facial masks and fever-reducing patches we are familiar with are all hydrogels.

When making gel ice and snow, Zhang Kai's team deliberately selected biocompatible materials, which are non-toxic, harmless, natural and environmentally friendly, and people can enjoy close contact with them.

Adding a layer of self-cooling device to the hydrogel can make ice plates and ice walls. When the temperature rises, the water does not drip, and can be used to make exquisite reliefs - this is the only technical solution in the world that can preserve reliefs on ice for a long time. The ice plates exhibited in the Science and Technology Museum are carved with "city towers" and "snowflakes". Although many people have touched them, the shapes of the patterns have always remained clear.

If you want to hold a small "ice and snow carnival" in the city, gel ice and snow are also easy to carry and install. At room temperature, you can roll it up, put a layer of ice on it, and add a refrigeration unit to turn it into a small ice rink that does not melt.

Gel ice and snow can provide a real ice and snow experience that cannot be matched by artificial ice. Moreover, its raw materials are cheap, the preparation method is simple, no expensive large-scale equipment is required, and it is easy to maintain during use, and the cost can be greatly reduced compared to artificial ice making technology.

There are many more interesting applications.

For example, a coffee shop with an ice and snow theme. The gel ice cups and ice bowls made with gel ice and snow will not melt or lose their shape, are tough, not easy to break, and can be reused. Imagine that a customer takes a beautiful ice cup and pours hot coffee into it. The coffee cools down, while the ice cup becomes soft and chewy due to the increase in temperature. This has great potential to become a popular check-in spot.

The material can also be further "revitalized". Gel ice and snow can introduce elements with optical, electrical, magnetic and other properties to achieve functional design, such as making it glow or making it into a refrigerator magnet.

The gel ice and snow team led by Professor Zhang Kai belongs to the wave dynamics team of the Department of Mechanics of the School of Aeronautics and Astronautics of Beijing Institute of Technology. The entire team mainly studies the shock absorption and noise reduction problems of large aerospace and underwater equipment. A few years ago, they began to study hydrogels, and their main focus was to combine it with acoustics to develop advanced acoustic materials for marine equipment and medicine. For example, the coupling agent applied to human skin during B-ultrasound is also a polymer hydrogel. The new hydrogel developed by the team can give patients a better experience and clearer B-ultrasound imaging. "Hydrogel is a material with great potential, and it will be able to show its prowess in many fields in the future." Zhang Kai said.

However, the combination of hydrogel and ice and snow is still a world first. Zhang Kai still remembers that more than four years ago, he received an email from the school encouraging teachers to actively use their research advantages to serve the Beijing Winter Olympics. Zhang Kai feels that as a scientific research team of BIT, a university with a glorious tradition of serving the country through science and technology, it is time to help promote ice and snow culture. In 2008, Zhang Kai watched the 110-meter hurdles competition at the Beijing Olympics and was deeply impressed by the Olympic atmosphere. "I just want to find a way to let more people get in touch with ice and snow, fall in love with ice and snow, and experience the ice and snow culture."

The team hopes that this non-melting ice and snow can bring the charm of ice and snow to more people.

Source: Science and Technology Daily