Reactive and decomposable dispersant for maximizing the properties of graphene composites

Abstract

Homogeneous dispersion of graphene in liquid media is essential for the fabrication of graphene-based composites. However, commercially available surfactants are not satisfactory in practical applications, having neither good efficiency nor the possibility to be eliminated from the final composites, and thus could have negative effects. Herein, a new dispersant, di-silanol group-grafted thiophene-ethylenediamine (DSiTE), featuring reactivity and decomposition capability was developed. Graphene dispersion with a concentration of up to 4 mg mL⁻¹ could be obtained at a DSiTE-to-graphene weight ratio of 1 : 1. The DSiTE molecule contains one thiophene core and six silanol groups, connected via a CN bond. The bond can be broken through acid treatment, making it possible for the dispersant to be eliminated from the composite after fulfilling its primary task of dispersing graphene. The exclusive features of DSiTE make it ideally suitable for fabricating highly conductive carbon films. Experimental results showed that the conductivity of a graphene film improved by about 48% after treatment with 1 mol L⁻¹ HCl. Moreover, because DSiTE possesses reactive silanol groups, it demonstrates mechanical enhancement in the case of the dispersant being preserved in the composite. The tensile strength of a graphene-coated paper increased by about 17% compared with that of an uncoated one. Overall, DSiTE showed superiority compared with commonly used conventional surfactants.