Preparation of Stable Dispersions of Chemically Reduced Graphene Oxide Through Noncovalent Interactions with Poly( N -Isopropyl Acrylamide)-Grafted Pluronic Copolymer

Stable dispersions of chemically reduced graphene oxide (RGO) were prepared by simple noncovalent interaction with poly( N -isopropyl acrylamide) (PNIPAAm)-grafted Pluronic (NGP). Prepared NGP/RGO assembly solutions showed temperature-dependent optical absorbance change below or above their lower critical solution temperature (LCST). Interestingly, LCSTs of NGP/RGO assemblies were unaffected compared with LCSTs of pristine NGPs regardless of the degree of PNIPAAm grafting in NGPs probably because noncovalent anchoring between PNIPAAm chains and RGO plates in NGP/RGO assembly is weak. This supports that PNIPAAm grafting on Pluronic occurred preferentially in hydrophilic PEO segments because hydrophobic PPO segments of NGP must be strongly anchoring on hydrophobic surface of RGO plates while PEO segments will be extended from RGO surface to aqueous medium.