A sweater made from new aerogel fiber tests warmer than one made from down

When woven into a sweater, a novel kind of aerogel fiber created by a group of chemical engineers and materials scientists from Zhejiang University in China has been shown to be warmer than down. The group outlines the idea for their fibers, their manufacturing process, and their performance in a cold environment in an article that was published in the journal Science. In the same journal issue, Zhizhi Sheng and Xuetong Zhang from the Chinese Academy of Sciences released a Perspective article summarizing the team's efforts on this new endeavor.

Aerogels are gels in which air is used in place of liquid. They were created in the 1930s and have found usage in many other fields, such as NASA spacecraft. Materials scientists have been attempting to utilize them to build fibers that may be used to generate warm fabrics because of their favorable thermal qualities. But thus far, the lack of moisture permeability and strength has caused most of these attempts to fail. The Chinese research team has solved both of these issues in their most recent study.

The researchers' first goal was to replicate the thermal characteristics of polar bear fur. They point out that the bears' ability to remain warm in such frigid conditions is due to the fact that the hairs that make up their fur coat have a thick outer layer and a porous center. The team started with a precursor, which they spun while it was frozen, to generate what they refer to as an encapsulated aerogel fiber, which recreates such properties. The sol-gel transition resulted from this mechanism. After that, the material was freeze-dried and given a semi-hard shell coating.

A thin, circular fiber that could be generated in the required lengths was the end product. The fact that textiles may be made without the requirement for post-processing indicates that the researchers' fibers could be manufactured at a lower cost than those that are now in use.

After that, the study team created lengthy strands of their fibers in batches, which they utilized to knit a sweater. Subsequently, they subjected the sweater to temperatures as low as -20°C to assess its warmth. They assert that compared to comparable sweaters made of cotton, wool, or down, the sweater showed superior thermal protection. Additionally, they stretched the sweater 10,000 times and discovered that it was largely undamaged. They also mention that the fiber is flexible, dyeable, and stretchable.