Preparation of ultra-high dispersed monolayer of perfluoroepoxy-oligomer grafted graphene oxide and its application prospects in fluorinated functional materials

An integrated strategy of ultrasound-enhanced graft/esterification of graphene oxide (GO) with hexafluoropropylene oxide oligomer ((HFPO)_n-COX) (UEGGH) is successfully proposed/established to prepare the highly dispersed GO monolayer (F_nGO-U). A series of F_nGO-U is efficiently achieved in mild conditions with controllable structure via UEGGH, and characterized via FTIR, XPS, Raman, XRD, FETEM and AFM. By systematically experimental investigation and computational simulations, the key role of the fluorinated chains and ultrasound is discerned. It is proved that the ultrasound may synergistically enhance the intercalation, graft/esterification and exfoliation of GO with (HFPO)_n-COX. Importantly, owing to the special repulsion among the grafted fluorinated chains and its effective inhibition to the spontaneous aggregation, F_nGO-U exists most dominantly in monolayer, and can be excellently dispersed in solvents, liquid (fluorinated) oligomers and polymer solutions. Finally, F_nGO-U is intentionally introduced/dispersed into PVDF-HFP and PFPE to evaluate/consolidate its superiority, and to develop its application in fluorinated functional materials. It was found that the mechanical properties and ionic conductivity of the prepared F_nGO-U/PVDF-HFP composite membranes are approximately three times higher than those of PVDF-HFP membranes. Moreover, the wear volume of the prepared F_nGO-U/PFPE composite lubricants is dramatically reduced to almost less than one fifth of magnitude compared to that of PFPE.