Covalent hyperbranched porous carbon nanospheres as a polymeric stationary phase for ion chromatography

This work presents a method for covalent quaternization of porous carbon nanospheres (PCNSs) and their application as anion exchanging stationary phase for ion chromatography. The PCNSs were covalently quaternized via the dehydration condensation between surface carboxyl groups and polyethyleneimine. This was followed by a repeated epoxy-amine addition reaction with ethylene glycol diglycidyl ether. As a result, surface methylamino groups are formed. The electrostatic interaction between quaternized PCNSs and sulfonated poly(polystyrene-co-divinylbenzene) resulted in the formation of an agglomerated stationary phase. The capacities (41.5-90.2 μequiv) and pressures (540-1150 psi) of column packed with novel phases (100 × 4.0 mm i.d.) were further increased with grafted polymer layer counts (2-5). Common inorganic anions, small organic acids and saccharides were rapidly separated on the new phases. The column efficiencies for seven inorganic anions ranged from 38,400 to 13,200 plates m^-1. Through 8 days of flushing test, the RSD values for retention time and efficiencies varied from 0.56% to 1.32%, and from 0.34% to 0.74%, respectively. Graphical abstract Schematic presentation of the covalent modification of porous carbon nanospheres (PCNSs) with hyperbranched quaternized polymers via the amidation and epoxy-amine addition reaction was depicted. Functionalized PCNSs were further applied as agglomerated materials of polymeric stationary phase for ion chromatography (IC).