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Herein we report on a versatile graf ting-to process combined with end group modification to prepare treelike polymeric ionic liquids which are covalently attached to graphene nanosheets. When cationic 3-ethyl-3-hydroxymethyloxetane (EHO) polymerization is initiated in the presence of dispersed hydroxy-functional graphene (FG) nanosheets, chain termination reactions account for highly effective grafting of hyperbranched poly(3-ethyl-3-hydroxymethyloxetane) (PEHO) onto FG. Tosylated PEHO hydroxy end groups are highly reactive alkylating agents for N-alkylimidazoles, thus enabling the incorporation of alkylimidazolium cations with tosylate counteranions as outer shell of the treelike FG-PEHO graft copolymer. In sharp contrast to FG, treelike FG-PEHO containing methylimidazolium tosylates as shell are readily dispersed in water to form stable dispersions without requiring either surfactant addition or high shear mixing. Moreover, these novel carbon/polymer hybrid materials self-assemble on surfaces and form films. In view of the facile tuning of their structures and properties, such treelike graphene polyelectolytes qualify for manifold applications.

Graphene functionalization by hydroxyalkylation and grafting with polyether polyols enables polyurethane (PU) nanocomposites formation by in situ polymerization with isocyanates combined with effective covalent interfacial coupling. Functionalized graphene (FG) hydroxylation is achieved either by alkylation, transesterification, or grafting of thermally reduced graphite oxide. In the presence of K2 CO3 as catalyst the reaction of FG-OH with ethylene carbonate at 180 °C affords hydroxyethylated FG, whereas transesterification with castor oil produces riconoleiate-modified FG polyols. In the "grafting-from" process, FG-alkoholate macro initiators initiate the graft polymerization of propylene oxide to produce hybrid FG polyols containing 38 and 59 wt% oligopropylene oxide. In the "grafting-to" process 3-ethyl-3-hydroxymethyl-oxetane is cationically polymerized onto FG-OH, producing novel hyperbranched FG-based polyether polyols. Whereas hydroxylation and grafting of FG greatly improve FG dispersion in organic solvents, polyols and even PU, as confirmed by transmission electron microscopy, matrix reinforcement of FG/PU is impaired by increasing alkyl chain length and polyol graft copolymer content.

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