Water-soluble graphene sheets with large optical limiting response via non-covalent functionalization with polyacetylenes

Water-soluble graphene sheet was prepared via chemical reduction of graphene oxide (GO) in the presence of polyacetylene bearing a quaternary ammonium pendant (Pac), with a relatively low feed ratio of 1/3 (Pac/GO, w/w). The non-covalent functionalization of graphene by Pac was mainly based on the electrostatic attraction and pi-pi interaction, the resultant material G-Pac showed good solubility in water with the concentration of 0.28 mg mL(-1). In virtue of the unique sp(2)-conjugated structure of graphene, it displayed a prominent optical limiting response, which could be potentially used in photonic or optoelectronic devices to protect human eyes or optical sensors from damage by intense laser irradiation.