Simultaneous reduction and functionalization of graphene oxide sheets with tannic acid for a strong composite material with multi-modally interactive interfaces

Abstract

A multi-modally interactive interface is investigated to develop a strong structural material based on hybridi-zation of graphene oxide (GO) and tannic acid (TA) through cross-linking with coordination and covalent bonds. GO is reduced and functionalized with TA by a simple wet-chemical reaction. The resulting TA-reduced and functionalized GO (TA-RGO) sheets are macroscopically assembled into lamellar structured paper like artificial nacre by vacuum-assisted filtration. The assembled TA-RGO paper is sequentially cross-linked by Fe3+ ion and polyethyleneimine (PEI) to form a strong interface through multimodal interactions such as hydrogen bonding, covalent bonding, coordination and pi-pi interactions. The suspended, assembled and cross-linked TA-RGO sheets are systematically characterized by various analytical tools. By forming the multimodal interactions, the tensile strength, modulus and toughness of GO paper were enhanced from 59.5 +/- 4.1 MPa, 7.8 +/- 1.4 GPa, and 765 +/- 112 kJ/m(3) to 167.7 +/- 15.4 MPa, 17.6 +/- 0.4 GPa, and 1484 +/- 192 kJ/m(3), respectively. Based on the results, we clearly demonstrated TA can be harnessed as a multifunctional agent for reducing, functionalizing and cross-linking RGO sheets to construct a strong structural material by forming multi-modally interactive interfaces.