A Thermally Insulating Textile Inspired by Polar Bear Hair

Abstract

Animals living in the extremely cold environment, such as polar bears, have shown amazing capability to keep warm, benefiting from their hollow hairs. Mimicking such a strategy in synthetic fibers would stimulate smart textiles for efficient personal thermal management, which plays an important role in preventing heat loss and improving efficiency in house warming energy consumption. Here, a "freeze-spinning" technique is used to realize continuous and large-scale fabrication of fibers with aligned porous structure, mimicking polar bear hairs, which is difficult to achieve by other methods. A textile woven with such biomimetic fibers shows an excellent thermal insulation property as well as good breathability and wearability. In addition to passively insulating heat loss, the textile can also function as a wearable heater, when doped with electroheating materials such as carbon nanotubes, to induce fast thermal response and uniform electroheating while maintaining its soft and porous nature for comfortable wearing.

Bioinspired Metamaterials: Multibands Electromagnetic Wave Adaptability and Hydrophobic Characteristics

“…However, researchers were simply concentrated in a specific waveband due to the great difficulty to achieve the compatibility of multispectral properties, which greatly hinders advance science and the application fields expanding of novel photonic materials. For example, in order to avoid the detection of microwave radar, infrared detector, and visual observation, the stealth materials on military armament have been separately developed during microwave, infrared, and visible light range; but the above stealth properties were difficult to be compatible in one weapon, thus, the problem of perfect stealth (stealth during full wavebands) is still not solved to date. Moreover, the material degradation by ultraviolet (UV) radiation also needs to be settled urgently because the weapons are exposed to sunlight all year round.…”

Investigating the effective thermal conductivity of moist fibrous fabric based on Parallel-Series model: a consideration of material’s swelling effect

“…The dead trapped air inside these mesopores, microvoids or grooves will not flow, which contribute to high heat insulation [47]. Another intriguing example for strengthening thermal insulation by the micro-porous structure of micro-channels is the polar bear hair [48]. However, these factors aren't considered in the P-S model, which in fact exist in the experimental fibers.…”

Emerging Materials and Strategies for Personal Thermal Management

“…Similar to achieving thermal insulation, Bai and co‐workers drew inspiration from the polar bear' hair and achieved the large‐scale fabrication of the so‐called biomimetic fibers with aligned porous microstructures via a “freeze‐spinning” method. [ 22 ] Mimicking the structure of the polar bear's hair, the fabricated biomimetic fibers have porosity as high as 87%, which benefits for thermal insulation. They then weaved the biomimetic fibers into a textile and covered onto a rabbit in the IR experiments in Figure 3C.…”