Synthesis And Characterization Of Hyperbranched Polytriazoles And Their Noncovalently Functionalized Graphenes

Due to its unique structures and properties, graphene has received tremendous attention in various fields such as biology, energy, electronics and polymer modification. According to the recent progress in organic/polymeric functionalization of graphene(or reduced graphene oxide; RGO), it is of great importance to prepare functionalized graphene(FG) with good dispersibility in common solvents and excellent reactivity for further functionalization. In this study, we have designed and synthesized the pyrene terminated hyperbranched polytriazoles(HBPs-Py) and grafted them to RGO through ?–? interactions. Then we have characterized the structures of HBPs-Py and investigated the properties of HBPs-Py-functionalized RGO(HBPs-Py-FG) systematically.Firstly, we synthesized HBPs-Py by "one-pot" condensation reaction by “click chemistry”, then 3-azidopropyl 4-(pyren-1-yl)butanoate(Py-N3) molecules were grafted to the terminal alkynyl groups of HBPs-Py with various feed ratios by click reaction. Subsequently, we directly solvothermally reducing GO in benzyl alcohol in the presence of HBPs-Py. The results confirmed that the grafting ratio of HBPs-Py is much higher than that of RGO functionalized with other normal polymers. The resulting HBPs-Py-FG sheets exhibit excellent dispersibility in various organic solutions including CHC l3, THF, BnOH, DMF and DMSO. The redispersed HBPs-Py10%-FG/CHCl3 solution has a high concentration of 5.9 ± 0.5 mg/mL, which contains a large number of alkynyl groups facilitating further applications.Finally, we have post- functionalized HBPs-Py10%-FG with 4-azidobenzenesulfonic acid(–SO3H) or octane-1-thiol(–C8) via two routes. We found that the remaining alkynyl groups of HBP-Py10% with excellent reactivity, which was helpful for further functionalization with desired functional groups. The post- functionalization approach is less efficient to graft HBP-Py10%–SO3H(or –C8) onto RGO surface, and the resulting solubility properties can be adjusted from water-soluble to oil-soluble by selecting a suitable functional groups for grafting.