Ultra strong pyroprotein fibres with long-range ordering.
Nat Commun
; 8(1): 74, 2017 07 13.
Article
em En
| MEDLINE
| ID: mdl-28706182
ABSTRACT
Silks are protein-based natural structured materials with an unusual combination of high strength and elongation. Their unique microstructural features composed of hard ß-sheet crystals aligned within a soft amorphous region lead to the robust properties of silks. Herein we report a large enhancement in the intrinsic properties of silk through the transformation of the basic building blocks into a poly-hexagonal carbon structure by a simple heat treatment with axial stretching. The carbon clusters originating from the ß-sheet retain the preferred orientation along the fibre axis, resulting in a long-range-ordered graphitic structure by increasing heat-treatment temperatures and leading improvements in mechanical properties with a maximum strength and modulus up to â¼2.6 and â¼470 GPa, respectively, almost four and thirty times surpassing those of raw silk. Moreover, the formation of sp 2 carbon configurations induce a significant change in the electrical properties (e.g. an electrical conductivity up to 4.37 × 103 S cm-1).The mechanical properties of silk are determined by tight stacks of sheet-like peptide crystals distributed in amorphous regions. Here, the authors heat and stretch silk fibres to align these crystal into a long range ordered carbon structure and dramatically enhance the silk strength.
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En
Ano de publicação:
2017
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