Ultra Strong Pyroprotein Fibres with Long-range Ordering

<p><b>Figure 1 | Schematic of long-range ordered pyroprotein-based fibre.</b> <b>a</b>, The structure of silk composed of highly aligned β-sheet crystals organised by the self-assembly of GX repeat units through a number of inter-/intra-chain hydrogen bonds and surrounding amorphous domains consisting of non-repetitive peptide chains. <b>b</b>, At temperatures in excess of 800 °C, disordered poly-hexagonal carbon units are formed by the pyrolysis of poly-peptide molecules. <b>c</b>, Following heating to 2,800 °C, the disordered poly-hexagonal carbon units developed into pseudo-graphitic domains. <b>d</b>, By axial stretching, pyroprotein-based fibres with well-arranged poly-hexagonal carbon units along the fibre axis are formed by heating to 800 °C. <b>e,</b> Long-range ordered graphitic structures evolve following heating to 2,800 °C.</p> <p><b> </b></p> <p><a><b>Figure 2 | </b></a><a><b>X-ray diffraction profiles of pyroprotein-based fibres by heating to 2,800 </b></a><b>°C</b><b>. </b><b>a,b</b> WAXD patterns, <b>c</b>,<b>d</b>, 1D radial integration profiles of entire 2D patterns, and <b>e</b>,<b>f</b>, 1D azimuthal intensity profiles of the radially integrated (002) peak with Gaussian fits for silk-fibre samples treated at different temperatures with and without axial stretching, respectively. </p> <p> </p> <p><a><b>Figure 3 | Heat-treatment temperature dependent microstructural characteristics of pyroprotein-based fibres by heating to 2,800 </b></a><b>°C.</b> <b>a</b>,<b>b</b>, Raman spectra, and <b>c</b>,<b>d</b>, TEM and selected area diffraction patterns of the pyroprotein-derived fibres with and without axial stretching, respectively, as a function of the HTT. The scale bars in the top-left image in panel c and d represent 10 nm. </p> <p> </p> <p><b>Figure 4 | Mechanical and electrical properties of the pyroprotein-based fibres as a function of the heat-treatment temperature. </b><b>a</b>, Tensile strength and <b>b</b>, Young’s modulus of the pyroprotein-derived fibre samples treated at different temperatures with axial stretching. <b>c</b>, Photograph of the SSF1200 bundle enduring 0.5 kg of loading weight. <b>d</b>, <i>V-I</i>​ curves of the pyroprotein-derived fibres for various HTTs and (inset) the conductivity obtained from the inverse slope of <i>V-I</i>​ curves as a function of the HTT.</p