Polar bears have fur that has a porous core encapsulated in a dense shell, a structure that keeps these animals warm and dry but is relatively lightweight.
- Chinese scientists have built on this idea in developing an encapsulated aerogel fibre.
- These synthetic fibres have mechanical properties that allow for weaving and knitting while at the same time being excellent thermal insulators.
- They can also be produced at scale with a simple two-step freeze-spinning and encapsulation process.
- Xuetong Zhang and Zhizhi Sheng of the Suzhou Institute of Nano-Tech and Nano-Bionics at the Chinese Academy of Sciences in Suzhou, China, have developed this new fibre. The details of the breakthrough have been published in the journal Science.
Building on nature: Aerogels are considered as an ideal material for thermal insulation. However, their application in textiles is greatly limited by their fragility and poor processability.
- The scientists overcame these issues by encapsulating the aerogel fibre with a stretchable layer, mimicking the core-shell structure of polar bear hair.
- Despite its high internal porosity over 90%, the new fibre is stretchable up to 1000% strain, which is greatly improved compared with that of traditional aerogel fibres (~2% strain).
- In addition to its washability and dyeability, the new fibre is mechanically robust, retaining its stable thermal insulation property after 10,000 stretching cycles (100% strain).
- A sweater knitted with the new fibre was only one-fifth as thick as down, with similar performance.
- The new synthetic fibre provides rich possibilities for developing multifunctional aerogel fibres and textiles.
The aerogel background: Aerogels have been considered as super thermal insulators since their invention in 1931. The successful adoption of aerogels, which are made by replacing the liquid in a gel with gas while maintaining a stable network, in NASA vehicles such as the Mars rover has inspired the use of aerogels in personal warming.
- However, applications of aerogels in textiles have been limited by their insufficient moisture permeability. Aerogel fibres are being developed to address the trade-off between thermal insulation and moisture permeability.
- Till now, aerogel fibres lacked the strength and flexibility necessary to allow weaving or knitting into a wearable fabric.
- The scientists have reported a feasible strategy to construct bioinspired knittable aerogel fibres with superb thermal insulation and mechanical robustness, which allows weaving into fabric with air permeability. This could instigate the development of advanced thermal textiles for personal warming.
