A rubber duck that was stuck to a seaside rock for more than a year has proved the strength of a new sticky material. The adhesive could be used in deep-sea robots and repair work, or as surgical glue for medical procedures.

“We developed a super-adhesive hydrogel that works extremely well even underwater – something very few materials can achieve,” says at Shenzhen University in China. Hydrogels are stretchy and soft materials.

Fan, then at Hokkaido University in Japan, and his colleagues analysed 24,000 sticky protein sequences from many different organisms to identify the stickiest combinations of amino acids, the building blocks of proteins. They used that information to create 180 different types of adhesive hydrogel. Then, they trained artificial intelligence models on the hydrogels’ material properties to predict even better recipes for super-sticky materials.

This process let the team develop a new class of versatile and sticky hydrogel. The material bonds to surfaces even when it has been unstuck and restuck multiple times or immersed in seawater, says Fan. It exceeded 1 megapascal of adhesion strength underwater – about 10 times stronger than most soft, sticky materials under the same conditions.

The research “demonstrates a paradigm shift in the way we can design high-performance soft materials”, says at Syracuse University in New York state. He praised the team for identifying stickiness patterns in natural proteins and capturing them in the new material.

The most whimsical demonstration of the hydrogel’s sticky strength involved keeping that yellow rubber duck attached to the wave-soaked rock by the shore. In a more practical experiment, the hydrogel instantly sealed a leaking water pipe. This suggests it could help repair underwater structures or make flexible electronics and robotics water-resistant.

Free newsletter

Sign up to The Weekly

Sign up to newsletter

The material was also biocompatible, which the researchers proved by implanting it under the skin of mice. This could make it useful for biomedical applications, such as affixing implants or working as surgical glue.

The hydrogel’s stickiness is remarkable, says Qin, but he notes that the material must be relatively thick to perform well. He hopes to see it tested outside ideal experimental conditions, especially in real-world situations with rough, contaminated or moving surfaces.

The researchers have submitted a patent for the new material through Hokkaido University, where most of them work.

Batteries enhanced with a polymer material that releases fire-suppressing chemicals at high temperatures are significantly less likely to explode into flames. This technique could boost the safety of battery-reliant machines, like electric cars and medical devices.

“Our approach enhances safety within mainstream liquid lithium batteries,” says at the Institute of Chemistry, Chinese Academy of Sciences. “It’s like popping open a safety valve – these chemicals smother flammable gases before they can explode, helping prevent fires.”

Zhang and her colleagues created and tested the flame-retardant polymer material in a prototype lithium metal battery. Such batteries are currently in limited use, but next-generation versions are candidates to replace the batteries in electric cars and portable electronic devices. That is because lithium metal can store 10 times as much energy as popular lithium-ion batteries by using pure lithium, rather than graphite, in the negative electrode.

The researchers exposed the prototype battery and a standard lithium metal battery to gradually hotter temperatures, starting from 50°C. When external temperatures rose above 100°C, both batteries experienced overheating – but the prototype’s special polymer material began breaking down automatically, releasing chemicals that act like “microscopic fire extinguishers”, says Zhang.

Beyond 120°C, the standard battery without safety features overheated to 1000°C within 13 minutes and burst into flames. But under the same conditions, the prototype battery’s peak temperature only reached 220°C, without any resulting fire or explosion.

This “innovative material science approach” can reduce the risk of battery fires or overheating, not only in lithium metal batteries but also in certain lithium-ion batteries and lithium-sulphur batteries, says at the SLAC National Accelerator Laboratory in California. It could lead to safer batteries, in particular for electric vehicles or even electric aircraft, he says.

Free newsletter

Sign up to The Earth Edition

Sign up to newsletter

The fire-suppressing technology would integrate well into existing battery manufacturing as a “near-term safety upgrade, while the industry pursues long-term solutions” involving alternative battery designs and chemistries, says Zhang. Still, injecting the polymer material into batteries would require some retuning of manufacturing processes, she says.