A Supramolecular Polymer Network of Graphene Quantum Dots

Graphene quantum dot (GQD)-organic hybrid compounds (GQD-2b-e) were prepared by introducing 3,4,5-tri(hexadecyloxy)benzyl groups (C16) and linear chains terminated with a 2-ureido-4-[1H]-pyrimidinone (UPy) moiety onto the periphery of GQD-1. GQD-2b-e formed supramolecular assemblies through hydrogen bonding between the UPy units. GPC analysis showed that GQDs with high loadings of the UPy group formed larger assemblies, and this trend was confirmed by DOSY and viscosity measurements. AFM images showed the polymeric network structures of GQD-2e on mica with flat structures (ca. 1.1nm in height), but no such structures were observed in GQD-2a, which only carries the C16 group. GQD-2c and GQD-2d formed organogels in n-decanol, and the gelation properties can be altered by replacing the alkyl chains in the UPy group with ethylene glycol chains (GQD-3). GQD can thus be used as a platform for supramolecular polymers and organogelators by suitable chemical functionalization.