Bioinspired Strong and Tough Organic–Inorganic Hybrid Fibers

Abstract

High‐strength and high‐toughness bio‐based fibers attract broad interest in biomechanical applications. Herein, strong and tough organic–inorganic regenerated silk fibroin/hydroxyapatite (RSF/HAP) hybrid fibers are prepared using a single‐channel microfluidic device. Calcium phosphate oligomers (CPOs) dispersed in the RSF matrix first grow into spherical amorphous calcium phosphates (ACPs), which then crystallize into needle‐like HAPs under a humidity condition, mimicking the biomineralization in collagen bundles. HAPs are better aligned along the RSF/HAP fiber direction after poststretching, forming a highly ordered and densely packed microstructure within the fiber and thus facilitating highly dense noncovalent interactions between rigid inorganic HAP nanocrystals and flexible organic RSF matrix. The highly dense noncovalent interactions endow the organic–inorganic hybrid fibers with superior mechanical properties and twisted RSF/HAP fiber bundles demonstrate a remarkable tensile strength of 778 MPa, a high Young's modulus of 17.8 GPa, a large tensile strain of 19.9%, and an excellent toughness of 121 MJ m−3 after proper twisting treatments. RSF/HAP hybrid fibers also show good performances against static loading, dynamic impact, and extreme cold condition and they can maintain their mechanical properties down to −50 °C. Therefore, the fibers are strong and tough and the strategy is facile and efficient.

Ultra‐Strong and Transparent Biomimetic Nanocomposite through Orientation Effects and In Situ Biomineralization

“…Today, various organic–inorganic nanocomposites with ordered hierarchical structures have been successfully developed (e.g., high‐performance fibers, stretch‐resistant films, and impact‐resistant laminates) and exhibit outstanding mechanical properties. [ 7–9 ] However, due to large size, anisotropic shapes, and surface chemistry of crystalline minerals, molding them into integrated texture with few defects still faces great challenge. [ 10 ] The inherent poor compatibility between inorganic nanomaterial and the organic matrix leads to weak interface interaction, [ 11 ] which together with the misalignment of building blocks, produces a heterostructure with a large amount of microscale defects that render the composites brittle and easy to fracture.…”