Flexible Polymer Ultra-Fine Fiber with Extreme Toughness.

Fiber materials with multilevel interior structures have myriad applications in many fields due to their unique properties. In this study, we develop a bioinspired flexible ultrafine polymer fiber via an integrated microfluidic-electrospinning technology. The fiber possesses periodic hollow and tubular chambers with a shell layer of approximately 150 nm in thickness extremely like natural bamboo. The single fiber with a diameter of ∼1.5 μm exhibits the Young's modulus ranging from 2 to 7 MPa measured with atomic force microscopy (AFM). The fiber with periodic hollow chambers and extreme toughness can find many applications in medicine, industry, and agriculture.