High-performance insulating nanopaper is made from bacteria

The team of Academician Yu Shuhong of the University of Science and Technology of China has developed a high-performance cellulose-based nanopaper material that maintains excellent mechanical and electrical insulation properties under extreme conditions. The results were recently published in Advanced Materials.

Preparation and structure diagram of composite nanopaper Courtesy of China University of Science and Technology

With the deepening of human exploration of extreme environments such as Antarctica, the moon and Mars, the emerging extreme environmental conditions, including strong ultraviolet environment, atomic oxygen and high and low temperature alternating environment, have become the main obstacles to future in-depth exploration.

In these extreme environments, the physical and chemical properties of materials can change, and in severe cases, even lead to the damage of important equipment and devices. Among traditional materials, metals and ceramics themselves have excellent mechanical properties and resistance to extreme environments, but metal materials face the problem of excessive density and weight, while ceramic materials face problems such as brittleness and difficult processing. Polymers are lightweight and malleable, but most polymer matrix composites currently serve in extreme environments for a long time, resulting in problems such as high-temperature softening and low-temperature brittleness. Therefore, the design and preparation of a high-performance protective material that can serve in extreme environments for a long time is one of the challenges faced by the materials field.

In nature, the mother-of-pearl “brick-mud” structure provides it with excellent mechanical properties. In recent years, other functions of this delicate ordered structure, such as water and oxygen barrier, and uniform dispersion of energy fields, have gradually become research hotspots.

Inspired by the natural mother-of-pearl “brick-mud” structure, in this work, the researchers first used aerosol-assisted biosynthesis method, using cellulose nanofibers produced by bacteria to uniformly and tightly entangle the dispersed synthetic mica nanosheets to obtain a composite hydrogel, and then obtained the final mother-of-pearl nanopaper material by hot pressing.

Thanks to the fine “brick-mud” structure and continuous three-dimensional network inside the nanopaper, the nanopaper exhibits excellent mechanical properties such as high strength, high modulus, high toughness, foldability and bending fatigue resistance. At the same time, the “brick-mud” structure inside the material gives full play to the high dielectric strength of mica, thereby giving the nanopaper a high electrical breakdown strength. Compared with pure cellulose nanopaper, the corona resistance life of this composite nanopaper is significantly improved, even exceeding that of commercial polyimide films.

In addition, the high-performance cellulose-based nanopaper reported in this study still shows excellent comprehensive performance under extreme conditions such as high and low temperature alternation, ultraviolet light and atomic oxygen, which provides an excellent protective material choice for people’s exploration of extreme environments in the future. (Source: Wang Min, China Science News)

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