Non-covalent synthesis of thermo-responsive graphene oxide–perylene bisimides-containing poly(N-isopropylacrylamide) hybrid for organic pigment removal

• Thermo-responsive graphene oxide is synthesized via non-covalent interactions.
• The material exhibits temperature-controllable assembly and disassembly behaviors.
• The graphene oxide can work as an efficient adsorbent for methylene blue removal.
• The adsorbent can be easily removed by filtration after the adsorption process.

In this work, thermo-responsive graphene oxide–perylene bisimides-containing poly(N-isopropylacrylamide) hybrid (TGO) was successfully prepared via non-covalent π–π stacking interactions of GO and perylene bisimides-containing poly(N-isopropylacrylamide) (PBI-PNIPAM). PBI-PNIPAM was synthesized by atom transfer radical polymerization of N-isopropylacrylamide, using bifunctional N,N′-bis[6-(2-chloropropionamide)hexyl] perylene-3,4,9,10-tetracarboxylic acid bisimide (PBI-Cl) as the initiator. The obtained polymer was then characterized by 1H NMR and fluorescence spectroscopy. The surface chemical states, morphology, and composition of TGO were characterized by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), respectively. This new hybrid showed reversible temperature-dependent self-assembly and disassembly at 35.9 °C in water. Therefore, it may have great potentials as a convenient adsorbent for removing organic pigment, as exemplified as for removing methylene blue from water with excellent adsorption capacity of 568 mg/g, high removal efficiency of 99.5%, and facile temperature-controlled post-separation of the adsorbent.

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