Amino Terminated Polyethylene Glycol Functionalized Graphene and Its Water Solubility
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1205-L02-09
Amino Terminated Polyethylene Glycol Functionalized Graphene and Its Water Solubility
Shifeng Hou1*, Robert D. Cuellari1, Najeeb Hoshang H. Hakimi1, Krutika Patel1, Pratik Shah1, Matthew Gorring2, Stefanie Brachfeld2 1. Chemistry & Biochemistry, Montclair State University, Montclair, NJ, USA. 2. Department of Earth & Environmental Studies, Montclair State University, Montclair, NJ, USA. * Corresponding Author: [email protected] ABSTRACT A chemical modification process was developed to functionalize graphene with specific groups. Graphene oxide (GO) was successfully functionalized with thionyl bromide which can be used as precursors for further functionalization. Amino terminated-polyethylene glycol (PEG-NH2) molecules were linked to single-layer graphene sheets through covalent bond. FT-IR, SEM and UV-vis spectroscopy techniques were used to characterize PEG modified graphene oxide and PEG modified reduced graphene oxide (PEG-RG). PEG-RG could disperse in water, tetrahydrofuran and ethylene glycol, with individual, single-layer graphene sheets spontaneously. The dispersion behavior of PEG-RG in an aqueous solvent has been investigated. A series of solutions of PEG-RG with concentrations of 0.001% to 1.5% were prepared and the PEG-RG dispersions exhibited long-term stability. In addition, a PEG-RG film with layered structure and high conductivity has been successfully prepared by filtration. INTRODUCTION Graphene has shown various unique properties, including superior mechanical strength and low density and high heat conductance [1, 2]. Many potential applications of graphene are based on its unique mechanical and electrical properties. Graphene oxide (GO) is water soluble with low conductivity and the reduced graphene oxide (RG) is a good conductivity with poor solubility in water. Generally, the solubility of GO in aqueous solution is because of its rich oxygen containing and hydrophilic groups, such as hydroxyl, epoxide and carbonyl groups. Upon a reduction process, most of the oxygen containing groups, hydroxyl, epoxide and carbonyl, will be totally removed and GO is converted to a rich π-conjugation graphene. The restoration of π-conjugation in graphene sheet can recover the conductivity of graphene but will scarify the solubility of graphene. RG is not compatible with other materials, such as most polymer matrices and limits its applications. To solve these problems, several techniques have been developed to modify the surface properties of RG and enhance its compatibility with other matrices and the solubility in aqueous and organic solvents[3, 4]. Potential techniques include
physically absorbed functional molecules onto graphene sheets, chemical covalent linked functional groups onto graphene surface [5, 6]. To date, the dispersion of RG in aqueous solvents has been accomplished via physically absorbed, aqueous soluble groups functionalized molecules on RG sheets with different molecules and polymers, but the presence of such stabilizers is not desirable for most applications. The dispe
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