Polar bear fur-inspired fibers offer exceptional thermal insulation, tested in a sweater

Researchers have developed a knittable aerogel fiber, drawing inspiration from the structure of polar bear fur. This innovative fiber showcases exceptional thermal and mechanical properties, allowing it to be washable, dyeable, durable, and well-suited for use in advanced textiles. The team tested these fibers in a sweater that exhibited impressive thermal insulation among other notable features.

While aerogels are excellent materials for thermal insulation due to their high porosity and extremely low thermal conductivity, their application in insulating fibers for textiles has been constrained by fragility and poor processability. These limitations have hindered the integration of aerogels into practical textiles, lacking the necessary strength and stretchability for weaving or knitting. Moreover, existing aerogel fibers are not machine washable and lose thermal insulation capability in wet or humid conditions.

Taking cues from animals residing in frigid climates, such as polar bears with their specialized fur, Mingrui Wu and colleagues employed a freeze-spinning technique to fabricate a robust polymeric aerogel fiber with lamellar pores. They enveloped this fiber with a thin, flexible rubber layer, emulating the core-shell structure of polar bear hair. This encapsulated aerogel fiber (EAF) not only delivered outstanding thermal insulation but also exhibited mechanical resilience, enabling knitting or weaving.

Despite possessing high internal porosity (over 90%), the newly developed fiber by Wu et al. demonstrated remarkable stretchability, accommodating up to 1000% strain—an immense enhancement compared to traditional aerogel fibers that achieve only around 2% strain. Impressively, even after 10,000 repeated stretching cycles at 100% strain, the fiber maintained its thermal insulation properties with minimal impact. Additionally, the authors established that the EAF is both washable and dyeable.

As proof-of-concept, Wu et al. crafted a thin sweater using these fibers, which, despite being roughly one-fifth the thickness of a down jacket, delivered comparable insulating performance. In a related Perspective, Zhizhi Sheng and Xuetong Zhang delve deeper into discussing the study’s nuances and implications.

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