Research On The Mechanical Properties Of Polar Bear Hair And Preparation Of Biomimetic Textiles

After millions of years of evolution and natural selection,natural materials usually have sophisticated multiscale structure,and thus have outstanding properties.For example,natural nacre with lamellar "brick-and-mortar" structure has light weight and high strength.Spider dragline silk is typical natural fiber with high strength and toughness.However,it is quite difficult to achieve the complex microstructure of natural materials in synthetic materials.As a result,mimicking the unique structure as well as excellent properties of natural materials is a common and effective way to develop materials with high performance.Living in extremely cold arctic regions,polar bears have special hairs with dense shell and hollow core.Specifically,the shell is composed of closely arranged microfibers along its axis and the core is hollow with lamellar pores perpendicular to its axis.This unique core-shell structure provides polar bear hair excellent thermal insulting properties.What's more,to ensure the thermal insulation and physical protection of themselves,polar bears need hairs with stable mechanical properties in the harsh and windy environment.In other words,stable mechanical properties of polar bear hairs are the basis of their thermal insulating abilities,and the multiscale structure is the basis of the stable mechanical properties.Based on this,the multiscale complex structure of polar bear hair was studied in depth in this paper,and its corresponding mechanical properties at room temperature and low temperature were explored by means of scanning electron microscope(SEM),dynamic thermomechanical analysis(DMA)and in-situ small angle X-ray scattering(SAXS).It was found that polar bear hair has a complex structure ranging from protein molecules at nanoscale to microfibers at micron scale.More importantly,polar bear hair could maintain outstanding toughness which is higher than most synthetic fibers at extremely low ambient temperatures.In addition,the surface hydrophobic properties of polar bear hair allow it to capture air underwater for good thermal insulation.Inspired by this,this paper prepared a superhydrophobic porous textile with superhydrophobic surface properties and aligned porous structure,which can capture air on the rough fiber surface and between fibers when entering water,thus having outstanding thermal insulating performance both in air and underwater.