Preparation And Performance Studies Of Silk Fibroin/Carbon Materials Composites

Silk fibroin (SF) is kind of natural fibrous protein macromolecule. Due to its outstanding mechanical property, biocompatiblity and sustainability, SF has been widely used in biomedical field. In this paper, various carbon nanomaterials, including graphene oxide (GO), multi-walled carbon nanotubes (MWCNTs), graphite powder (GP) and acetylene carbon black (CB), were introduced into SF matrix. The achieved composites were characterized by SEM, FT-IR, XRD, DMA and BDS to investigate the influcence of carbon nanomaterials introduction on SF molecular conformation, composite microstructure, mechanical and dielectric properties. Further discussion on main factors and mechanism of the influence were performed. The following results have been achieved:(1) The GO and GP introduction would induce SF molecular conformation transformation to β-sheet. At low content range, composites’ β-sheets content increases firstly and then decreases along with GO and GP content increasing. Comparatively, the composites’ dynamic storage modulus shows the same trend, which indicates correlation between β-sheets content and composites’ mechanical property.(2) The solubilities of MWCNTs, GP and CB in SF solution can be improved by introducing amphipathic GO, which also presents positive effect on improving the dispersion stability of the three insoluble carbon materials in SF solution.(3) Microstructure of carbon materials have obvious influence on its enhancement effect in SF. The experiments indicat that all three carbon nanomaterials, GP, MWCNTs and CB, can induce SF molecular conformation transformation to β-sheet, which consequently improves composites’ mechanical and dielectric properties. In the case that three carbon materials are at the same content (1.5wt%), SF/MWCNTs composite has the highest storage modulus, and SF/CB composite has the highest dielectric constant.(4) Post-treatment methods show significant effect on SF molecular conformation, which induce SF molecular conformation transformation from random coils to β-sheets.