Polymeric ion functionalized graphite nanoplatelets with flowability

Abstract

To expand the gallery of graphite functional materials, a graphite nanoplatelet fluid (GNF) is obtained via a three-step procedure, involving acid intercalant-assisted ultrasonic exfoliation, covalent grafting with a charged polysiloxane quaternary ammonium salt (DC5700), and ion exchange with a poly(ethylene) glycol-functionalized sulfonate salt (NPES). The obtained GNF exhibits flowability at room temperature exempted from any solvent. The ‘two step’ increase in thickness compared with its parent counterpart is attributed to the coverage of charged organic oligomer (DC5700/NPES bilayer) on the basal plane of GNP. The energy-dispersive x-ray (EDX) analysis of the intermediate and final products also demonstrate the existence of silicon (Si) in GNP-DC5700 and the appearance of sulfur (S) in GNF. Moreover, a relatively as high as ca. 78 wt% of organic fraction is calculated from thermal gravimetric analysis, which indicates 3.2 polymeric ion molecule per 100 carbon atoms. Typically, the digital photographs and zeta potential analysis of GNF aqueous solution demonstrates its good stability. Therefore, the polymeric ion bilayer and GNP are integrated into one single-component and macroscopically homogeneous, and thus can remain microscopically stable even under giant shearing force, making the novel GNF great potential as lubricants, plasticizers and functional nanofillers, etc.