Highly water-dispersible methylpyridinium salt functionalized reduced graphene oxide and poly(vinyl alcohol) composites

The main issues with developing graphene as a reinforcement are its mono-dispersive properties and strong interfacial bonding between matrix and graphene. In this study, we synthesized reduced graphene oxide (rGO) that is mono-dispersive in polar solvents, by designing structural isomers (-para and -meta) for poly(vinyl alcohol) (PVA) nanocomposites. The hydrazine-methylpyridine synthesized with different structural isomers was used to reduce and functionalize graphene oxide (GO). The -meta structural isomers showed a higher reduction rate and functional groups on GO than -para due to the difference in electrophilic strain. In particular, the prepared rGO reduced by meta-hydrazine-methylpyridine (m-Py-rGO) exhibited excellent mono dispersive characteristics in water solvents as well as in PVA matrix. As a result, nanocomposites containing 1 wt % m-Py-rGO increased in tensile strength and modulus by 48 % (85.95 MPa) and 82 % (4.27 GPa), respectively, compared to pristine PVA. In this study, a method for manufacturing rGO with excellent dispersibility in water, an inexpensive solvent, and its application method are presented.