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The effect of oxidation on properties of graphene and its polycaprolactone nanocomposites.
Dao, Trung Dung,Oh, Kyung Min,Choi, Jin Taek,Lee, Hyung-Il,Jeong, Han Mo,Kim, Yong Sung,Park, Sung-Jin,Kim, Byung Kyu American Scientific Publishers 2012 Journal of nanoscience and nanotechnology Vol.12 No.11
<P>A functionalized graphene sheet (FGS), which was prepared by the thermal reduction of graphite oxide, was modified by oxidation with H2O2. Elemental analysis, X-ray photoelectron spectroscopy, and Fourier transform infrared (FTIR) spectroscopy showed that additional oxygen functional groups, either doubly or singly bound to carbon, were created by the oxidation. The size and electrical conductivity of the FGS were reduced by the oxidation. During FGS/Polycaprolactone (PCL) nanocomposite preparation by an in situ polymerization method, PCL was grafted onto a FGS by chain growth from a functional group on FGS such as hydroxyl. Thermogravimetry and FTIR spectra demonstrated that the amount of grafted polycaprolactone (PCL) was decreased by the oxidation of FGS, suggesting that PCL chain growth from the FGS surface was inhibited by the neighboring carboxylic acid group on the FGS. Enhanced compatibility between the oxidized FGS and the PCL matrix was observed by optical microscopy and scanning electron microscopy. The reinforcing effect on tensile properties was also enhanced by the oxidized FGS in the FGS/PCL nanocomposites. This suggests that the surface coverage by the grafted PCL chains on the oxidized FGS is higher than that on a pristine FGS, although the grafted PCL chain length is shorter and the amount grafted is smaller.</P>
김정호,Trung Dung Dao,정한모 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.33 No.-
Multi-walled carbon nanotube (CNT) was hybridized with aluminum hydroxide utilizing aluminumtrichloride hexahydrate as a precursor to prepare a filler that can be utilized for a thermally conductiveyet electrically insulative polymer composite. The thermal conductivity of an alumina sphere/thermoplastic polyurethane (TPU) mixture (100 parts) was enhanced 2 to 3-fold when 5 parts of thishybrid material (Al–CNT hybrid) was added as a synergizer for thermal conduction. This enhancementwas better than that by CNT. Moreover, the electrical conductivity increase due to the added Al–CNThybrid was marginal, whereas the increase was striking when CNT itself was added instead.
Kim, Ki Tae,Dao, Trung Dung,Jeong, Han Mo,Anjanapura, Raghu V.,Aminabhavi, Tejraj M. Elsevier 2015 Materials chemistry and physics Vol.153 No.-
<P><B>Abstract</B></P> <P>Graphene was oxidized with H<SUB>2</SUB>O<SUB>2</SUB> to introduce additional anchoring sites for effective alumina coating on graphene by the sol–gel method. The X-ray photoelectron spectroscopy studies showed that the oxygen-containing groups such as hydroxyl group useful for coating were introduced by the oxidation. The transmission electron microscopy images and thermogravimetric analysis data demonstrated that the additional anchoring sites enhanced the efficiency of the alumina coating. A small amount of alumina-coated graphene synergistically improved the thermal conductivity of the alumina sphere/thermoplastic polyurethane (TPU) composite without any increase in the electrical conductivity, because the electrical conductivity of graphene effectively decreased by the alumina coating. Moreover, the synergistic effect of a small amount of graphene was enhanced by the alumina coating, and the stiffening of the alumina sphere/TPU composite due to the added graphene was alleviated by the alumina coating.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Oxidation of graphene with H<SUB>2</SUB>O<SUB>2</SUB> introduced anchoring sites for alumina coating. </LI> <LI> The anchoring sites improved the efficiency of alumina coating on graphene. </LI> <LI> The alumina-coated graphene synergistically enhanced the thermal conductivity. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Compatibility of Functionalized Graphene with Polyethylene and Its Copolymers
Seo, Hyeon Myeong,Park, Jin Ho,Dao, Trung Dung,Jeong, Han Mo Hindawi Limited 2013 Journal of nanomaterials Vol.2013 No.-
<P>The compatibility of polyethylene (PE) with a functionalized graphene sheet (FGS), which was prepared by the thermal reduction of graphite oxide, was examined in this study. The dispersion of the FGS in the PE was improved as the molecular weight of the PE was decreased. The PE copolymers containing polar comonomers such as maleic anhydride or acrylic acid exhibited better compatibility with FGS than the PE homopolymers. The compatibility of the FGS with PE copolymers containing small amounts of comonomers, which have a solubility parameter slightly larger [up to approximately 0.5 (J/cm<SUP>3</SUP>)<SUP>1/2</SUP>] than that of PE itself, was better than the compatibility of both the PE and PE copolymers containing larger amounts of comonomers. The morphology, electric conductivity, and tensile properties of FGS/PE copolymer/PE nanocomposites showed that the copolymers with a solubility parameter slightly larger than that of PE effectively served as a compatibilizer in FGS/PE nanocomposites.</P>