Photograph showing the bending and twisting of an encapsulated airgel textile. Credit: Science (2023). DOI: 10.1126/science.adj8013
A team of chemical engineers and materials scientists from Zhejiang University in China developed a new type of airgel fiber that was found to be warmer than down when woven into a sweater. In their article published in the journal Science, the group describes the inspiration for their fibers, how they were made, and how well they performed when tested in a cold environment. Zhizhi Sheng and Xuetong Zhang of the Chinese Academy of Sciences published a Perspective article in the same journal issue describing the work the team did in this new effort.
Aerogels are types of gels in which the liquid is replaced by air. They were invented in the 1930s and have been used for various applications, including in NASA space vehicles. Due to their positive thermal properties, materials scientists have tried to make fibers that could be used to create warm textiles. So far, these attempts have mostly failed, due to a lack of moisture permeability and strength. In this new study, the Chinese research team found a way to overcome both problems.
The researchers’ work began with the aim of imitating the thermal properties of polar bear fur. They note that the reason bears can stay warm in such cold temperatures is because the hairs that make up their coats have both a porous core and a dense shell. To recreate such attributes, the group created what they describe as an encapsulated airgel fiber starting with a precursor, which they spun while frozen. This process led to a sol-gel transition. The material was then freeze-dried and coated with a semi-hard shell.
The result was a fine round fiber that could be produced in desired lengths. The researchers note that no post-processing is needed to produce textiles, suggesting that their fibers could be produced more cheaply than those currently used.
The research team then produced batches of their fibers into long strands which they used to weave a sweater. They then tested the warmth of the sweater by exposing it to temperatures as low as −20°C. They claim the sweater demonstrated better thermal protection than similar down, wool or cotton sweaters. They also stretched the sweater 10,000 times and found that it suffered little damage. They also note that the fiber can be stretched, dyed and folded.
More information:
Mingrui Wu et al, Biomimetic and knitable airgel fiber for thermal insulation textile, Science (2023). DOI: 10.1126/science.adj8013
Zhizhi Sheng et al, Imitating polar bear hair in airgel fibers, Science (2023). DOI: 10.1126/science.adm8388
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Quote: A sweater made from new airgel fibers tested warmer than a down sweater (December 22, 2023) retrieved December 22, 2023 from
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