Preparation of graphene oxide-coated silk fibers through HBPAA [a molecular glue]-induced layer-by-layer self-assembly

Carbon nanomaterials recently gained extensive interests for their good application potential in composite nanomaterials because of their unique physicochemical properties. In this study, graphene oxide (GO)-coated silk fibers were fabricated through HBPAA-induced layer-by-layer (LbL) self-assembly technology. The closely adhered GOs coatings were achieved by circular incubation with solutions of hyperbranched poly (amidoamine) (HBPAA) and GOs, with HBPAA serving as the “molecular glue” that could bind single or mutilayered GOs to the surface of silk fibers. In the experiments, GOs nanosheets were synthesized by a modified Hummers method and were characterized by atomic force microscopy, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Our developed technology was able to tightly bind GOs to the silk surface and control their loading capacity. Owing to the positive charges and abundant amino end groups of HBPAA, GOs were found to be completely adsorbed onto silk surface. Therefore, their assembly would be green and controllable. The Fourier transform infrared (FTIR) spectroscopy, XPS, XRD, Thermogravimetric analyses (TGA) confirmed the attachment of HBPAA and GOs. Field mission scanning electron microscopy (FESEM) indicated that GOs closely spread on the surface of silk fibers without any self-folding though excessive stacking were observed in a small part of a silk surface with the increased density of GOs coatings. The developed LbL self-assembly technology may provide a controllable approach to coat GOs on the surface of biological fibers and graphene-based functional materials.