Artificial spider silk from ion-doped and twisted core-sheath hydrogel fibres

Yuanyuan Dou,Xiang Zhou,Tianjiao Jia,Dong Qian,Wenqian He,Xiaoyu Hu,Pingchuan Sun,Zhuangjian Liu,Jingjing Li,Zunfeng Liu,Shaoli Fang,Kai Wen,Zhen-Pei Wang,Enlai Gao

doi:10.1038/s41467-019-13257-4

Abstract

Spider silks show unique combinations of strength, toughness, extensibility, and energy absorption. To date, it has been difficult to obtain spider silk-like mechanical properties using non-protein approaches. Here, we report on an artificial spider silk produced by the water-evaporation-induced self-assembly of hydrogel fibre made from polyacrylic acid and silica nanoparticles. The artificial spider silk consists of hierarchical core-sheath structured hydrogel fibres, which are reinforced by ion doping and twist insertion. The fibre exhibits a tensile strength of 895 MPa and a stretchability of 44.3%, achieving mechanical properties comparable to spider silk. The material also presents a high toughness of 370 MJ m−3 and a damping capacity of 95%. The hydrogel fibre shows only ~1/9 of the impact force of cotton yarn with negligible rebound when used for impact reduction applications. This work opens an avenue towards the fabrication of artificial spider silk with applications in kinetic energy buffering and shock-absorbing.

Highlights

Spider silks show unique combinations of strength, toughness, extensibility, and energy absorption
Biochemical and chemical methods have led to the development of artificial spider silks, such as protein fibres[13], supramolecular hydrogel fibres[14], and carbon nanotube (CNT) composite fibres[15]
This may result from a poor understanding of the key structural characteristics of natural spider silks that are responsible for their mechanical properties and the difficulties faced when combining different structural models, such as amorphous regions crosslinked with crystallites[6], spiral nanofibres[7], and skin-core structures[8], to prepare artificial spider silks

Summary

Introduction

Spider silks show unique combinations of strength, toughness, extensibility, and energy absorption. This work opens an avenue towards the fabrication of artificial spider silk with applications in kinetic energy buffering and shock-absorbing Natural structural materials such as biofibres and biocomposites have shown extraordinary mechanical performance through the process of evolutionary selection[1]. The artificial silk fibres based on regenerated silk proteins are the most widely studied, and promising mechanical properties (breaking strength ∼1.34 GPa, breaking strain of ∼36%, and toughness of ∼334 MJ m−3) have been obtained (Supplementary Table 1). These fibres based on regenerated silk proteins approach the mechanical properties of natural spider silks (breaking strength of ∼1.6 GPa, breaking strain of ∼80%, and toughness of ∼350 MJ m−3), it is still difficult to prepare artificial spider silks using a non-protein approach This may result from a poor understanding of the key structural characteristics of natural spider silks that are responsible for their mechanical properties and the difficulties faced when combining different structural models, such as amorphous regions crosslinked with crystallites[6], spiral nanofibres[7], and skin-core structures[8], to prepare artificial spider silks. The core, which comprises an elastic inner centre surrounded by a plastic outer layer, is the key part to provide the mechanical properties of the silk, with the skin layer affording some protection against environmental impact[18]

Methods

Results

Conclusion