Fluorescent whitening agent stabilized graphene and its composites with chitosan

Individually dispersed graphene colloid is prepared using common and industrially available fluorescent whitening agents (FWAs) as stabilizers. Characterizations by UV-vis, fluorescence and Raman spectra demonstrate that FWAs are successfully anchored onto graphene sheets by π-π interaction. The results from AFM indicate the individual dispersion of graphene sheets in water. FWAs are demonstrated as highly efficient in suspending graphene with high concentration(6.2 mg ml^-1). Subsequently, the obtained graphene sheet is incorporated into a chitosan (CS) matrix by solution casting to fabricate CS/graphene composites. Morphological observations substantiate the homogeneous dispersion of graphene in the CS matrix and the strong interfacial adhesion between them. The significant improvements in tensile strength and toughness of the composite films are concurrently observed.