Synergistic effect of Cu2+-coordinated carbon nanotube/graphene network on the electrical and mechanical properties of polymer nanocomposites

A novel hybrid nanofiller system, in which oxidized multi-walled carbon nanotubes (MWCNTs) and chemically modified graphene (CMG) are coordinated by copper ions, is fabricated. The CMG sheets are efficiently isolated and bridged by MWCNTs through copper ion coordination to form a uniform network, and the Cu2+-coordinated MWCNT/CMG network can be easily introduced to a variety of polymer matrices by solution mixing. For example, the Cu2+-coordinated MWCNT/CMG network is successfully incorporated in poly(styrene-co-butadiene-co-styrene) (SBS), one of the most widely used synthetic rubbers. The molecular-level dispersion of the nanofillers in the SBS matrix facilitates efficient electron and load transfer. The Cu2+-coordinated MWCNT/CMG network demonstrates a synergistic effect that cannot be achieved by simple physical mixing of the two nanofillers. The obtained SBS nanocomposites have much better electrical and mechanical properties than those filled with MWCNTs, CMG or a non-coordinated hybrid nanofiller system at the same loading. This fabrication method may open the door to a new class of high-performance polymer-matrix composites.