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Stretchable ceramic nanofiber aerogel was prepared by three-dimensional reactive electrospinning

Time : 2022-05-23 Hits : 26

Ultralight ceramic aerogel is widely used in thermal, electrical, magnetic, medical, optical and chemical fields due to its low density and thermal conductivity, high specific surface area, high porosity and chemical and thermal inertia. However, the traditional ceramic aerogel is brittle and difficult to process, and is prone to structural collapse under high external stress or strain, which limits its application in extreme environments such as aerospace and national defense. Therefore, it is still difficult to improve the tensile properties of ceramic aerogel by structural design.

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Recently, donghua university research team using three-dimensional reaction synthesis method of a kind of electrostatic spinning with 3 d weaving curl nanofibers structure ceramic aerogel (ICCAs), the aerogel has excellent mechanical properties and thermal stability, for simple, fast, low cost for mass production with complex shape ceramic nanofibers provides reference.

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Three-dimensional reactive electrostatic spinning is controlled by sol-gel reaction in the jet. By adjusting the protonation degree of colloidal particles, the gelation rate of the sol jet can be controlled and the shape of the jet can be precisely controlled in milliseconds. In this study, the spray mode of conical droplet was changed to multi-spray mode by adding a small amount of polymer in sol solution with high conductivity and low viscosity, while the condensation between colloidal particles was not affected. Due to the high surface potential, the jet is elongated into a slender direct flow, forming a three-dimensional curl structure. The highly reactive colloidal particles form a highly crosslinked and solid skeleton through condensation and jet solidification, which inhibits the deformation and collapse of the structure of the 3D crimped nanofibers. Finally, the aerogel precursor was calcined in air at 1000℃ for 1h to obtain ICCAs.

Compared with the layered structure of traditional ceramic fiber materials and the pearl chain structure of traditional ceramic aerogel, ICCAs has a three-dimensional interlacing cribed nanofiber structure, which still has good thermal stability even after calcination at 1400℃. Moreover, ICCAs can be stretched and knotted without any visible breaking. With a density of 6 mg/cm3 and a weight of 0.06 g, ICCAs can withstand about 3,300 times its own weight without breaking.

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ICCAs has excellent tensile elasticity, fatigue resistance and ductility. It can be stretched from the initial form to 100% tensile strain without fracture, and the tensile fracture stress is 12.7kpa. ICCAs can withstand 1000 tension-release cycles at 40% strain; When the oscillating strain is 5%, the energy storage modulus, loss modulus and damping ratio remain unchanged after 100,000 times of stretching. After roasting at 1300℃ for 1h, ICCAs still showed excellent ductility and tensile strain up to 48.3%.

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With low thermal conductivity, high stretchability and flexibility, ICCAs can be used as a thermal insulation material in extreme environments and are simple to prepare. The ceramic nanofiber aerogel precursor with a length of 170 cm, a width of 130 cm, a height of 12 cm and a weight of 313 g can be easily and quickly prepared within one hour through the pilot plant.

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ICCAs features ultra-light weight, thermal insulation, robust structural stability, tensile and fatigue resistance, making it potentially useful for personal protective equipment, space vehicle thermal protection systems and flexible wearable electronics. Related work was published in Nature entitled "Direct synthesis of highly stretchable ceramic nanofibrous Aerogels via 3D reaction electrospinning" Communications.

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