（様式６号） 「課程博士用」
学 位 論 文 の 要 旨
専 攻 名 材料科学 専 攻 氏 名
ふ り が な
ナビハ アブドラー ○
印学位論文題目
Preparation and Properties of Polymer Modified Graphene Materials
（高分子で修飾されたグラフェン材料の調製と性質）
Since the discovery of graphene by Geim and co-workers in 2004, graphene has attracted widespread attention due to its unique properties. Graphene is a 2-D form of graphite and consists of a single layer of sp2 hybridized carbon atoms in a honeycomb lattice. Because of its unique properties, such as high surface area, excellent thermal and electrical conductivities, and strong mechanical strength, graphene has stirred the interest of academic and industrial researchers in various fields. The present thesis is a collection of studies concerning with functionalization of graphene-based materials. This thesis consists of three chapters. The first chapter describes the synthesis and characterization of graphene flakes. The second chapter describes preparation of chemical functionalization of graphene flakes with organic polymer. Finally, the last chapter is about preparation of graphene/silica hybrid.
【Chapter 1】
Graphene flakes (GFs) were prepared from ultrasonication of graphite nanoplatelets (GNP) in N-methylpyrrolidone (NMP) as solvent. The study was undertaken to evaluate the effect on GFs sizes and thicknesses by different powers (310 and 180 W) and the time (3–300 min) of ultrasonication. From this study, clearly that the two variables affected the condition of GF.
Transmission electron microscopy (TEM) shows that the size of the GFs is at the optimum size when using 180 W of ultrasonication power for 3 min (~2.3 μm) whereas the minimum size is about 0.6 μm after using 310 W of ultrasonication power for 300 minutes. Raman spectroscopy and thermal gravimetric analysis (TGA) were used to investigate the graphitic characteristics and thermal stability of the exfoliated GNP. The ratio of D band intensity to the 2D band intensity (ID/I2D) of Raman Spectroscopy shows that, as the time and power of ultrasonication increase, the thickness of GFs is reducing.GF produced was stable up to 1000 ⁰C. The ultrasonication method in NMP can be used to produce GFs and facilitates to a broad range application of graphene such as in polymer composites and lithium ion batteries.
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（様式６号－続紙） 「課程博士用」
氏 名
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ナビハ アブドラー ○
印【Chapter 2】
Solubilization of graphene is practically important for fabrication of graphene materials.
Covalent or noncovalent of functionalization of graphene improves its solubility (dispersibility).
In order to increase the dispersibility of graphene flakes, poly(ε-caprolactone) (PCL) was introduced on the graphene flakes by grafting-on technique. A well-defined PCL with terminal azido group was prepared via living ring-opening polymerization of ε-caprolactone (CL) using a functional initiator. Grafting-on reaction between the azido-terminated PCL (N3-PCL) and ultrasonication-assisted exfoliated graphene flakes (GFs) was carried out to obtain PCL-grafted-graphene flakes (PCL-g-GFs) through nitrene chemistry. The resulting PCL-g-GFs showed good dispersibility in a wide variety of organic solvents. GPC, 1H NMR, IR, Raman, UV-vis, and TEM measurements indicated that PCL macromolecules were covalently introduced on the surface of GFs without disrupting the optical property of GFs.
【Chapter 3】
Hybrid materials are composites consisting of two constituents at the nanometer or molecular level. Although a great deal of research has been conducted on the preparation of polymer/silica hybrids, only a few studies have been reported on graphene/silica hybrid using graphene as an organic segment. In order to increase the miscibility of graphene and silica, polar polymer, poly(2-methyl-2-oxazoline) (PMeOXz), was introduced onto graphene surface.
Firstly, PMeOXz with terminal amine functionalities was prepared by living ring-opening polymerization of 2-methyl-2-oxazoline (MeOXz). Secondly, condensation reaction of the amine-terminated PMeOXz was carried out to give PMeOXz-functionalized graphene oxide (GO), which was then reduced to PMeOXz-functionalized reduced GO (RGO). Finally, hydrolysis and polycondensation reaction (sol-gel reaction) of tetraethoxysilane (TEOS) was carried out in the presence of PMeOXz-modified RGO to obtain a hybrid material composed of RGO and silica.
