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- 저자 : Wantai Yang (검색결과 4 건)
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Dong Liu,Xiaoying Du,Jianping Deng,Wantai Yang 한국고분자학회 2011 Macromolecular Research Vol.19 No.7
Optically active gels based on helical N-propargylamide polymers were prepared using a one-pot twostep methodology: the pre-formation of helical N-propargylamide copolymer (defined as N=N-HP) and the preparation of gels bearing the helical copolymers. To prepare N=N-HP, N-propargylamide M1, which contained -N=Nfunctional group, and M2, which provided helical polymer chains for the resulting copolymers, underwent copolymerizations in the presence of (nbd)Rh^+B^-(C_6H_5)_4 as a catalyst. -N=N- groups in N=N-HP acted as an initiator to induce the free radical polymerization of styrene, yielding the designed gels. Trimethylol propane triacrylate (TMPTA) was used to improve the cross-linking degree of the gels. The obtained gels were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and circular dichroism (CD) spectroscopy measurements. The gels showed high optically activity, resulting from the helical structures of the N-propargylamide polymer chains. Preferential adsorption towards (R)-(+)-1-phenylethylamine in the two enantiomers was observed in the obtained gels, demonstrating the potentials of such gels in chiral recognition and chiral resolution.
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Yaping Sheng,Qigu Huang,Haibing Huang,Mengshan Yu,Xinli Zhang,Lu Cheng,Zhi Liu,Wei Liu,Jianjun Yi,Wantai Yang 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.2
The copolymerization of MMA with ethylene was promoted by metallocene complex in the presence ofinitiator tetra(2,3-epoxy propoxy)silane (Is), reducing agent Zn and cocatalyst MAO, combining freeradical polymerization with coordination polymerization via sequential monomer addition strategy inone-pot to produce 4-arms hydroxy-functionalized PMMA-b-PE. The effects of polymerizationconditions such as temperature, time, ethylene pressure and Al/Ti molar ratio on the polymerizationperformance were investigated. 4-Arms hydroxy-functionalized PMMA-b-PE was obtained by solventextraction and determined by GPC, MALLS, DSC, FT-IR, WAXD and 1H(13C) NMR. The DSC result indicatedthat the 4-arms hydroxy-functionalized PMMA-b-PE had one Tg at 87.0 ℃ and one Tm at 117.0 ℃ whichattributed to Tg of PMMA segment and Tm of PE segment, respectively. The microstructure of 4-armshydroxy-functionalized PMMA-b-PE was further confirmed by WAXD, FT-IR, and 13C NMR analysis. These results demonstrated that the obtained 4-arms block copolymer consisted of PMMA segment andcrystalline PE segment.
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Zhi Liu,Qigu Huang,Mengshan Yu,Jing Wang,Fengjiao Li,Lu Cheng,Jiangping Guo,Yang Zhou,Baichun Zhu,Jianjun Yi,Yunfang Liu,Wantai Yang 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.4
Preparation of novel polyethylene/carbon nanotubes (CNTs) nanocomposites with core–shell structure was presented. The method involved in situ ethylene polymerization in which nanotube surface was treated with Grignard Agent, followed by reacting with active transition metal compound, TiCl4. The multiwalled carbon nanotubes (MWCNTs) supported catalysts polymerize ethylene to form polymer nanocomposite. MWCNTs were homogeneously dispersed within polymer matrix, and as expected, the resultant nanocomposites featured core–shell structure which was confirmed by HRTEM. For the nanocomposite, the microscopic examination of the cryogenically fractured surface not only ensured a good distribution of carbon nano-particles in the PE matrix but also revealed the ductile-like fracture. The Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) were employed for the study of covalent sidewall functionalization and chemical bonding environment of MWCNTs, also indicated effective immobilization of titanium catalyst on the MWCNTs surface. The crystalline properties, dielectric property and thermal stability of the nanocomposites were determined by WAXD, impedance analyzer and TGA. The dielectric result showed a slight decline of the dielectric constant of the nanocomposites with increase of the polymerization time, and lower dielectric loss was also observed.
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Zhi Liu,Xinli Zhang,Haibing Huang,Jianjun Yi,Wei Liu,Weijiao Liu,Hongpeng Zhen,Kejing Gao,Mingge Zhang,Wantai Yang,Qigu Huang 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.6
A new method was presented for preparing (co-)polyethylene with broad molecular weight distribution (MWD) and high molecular weight employed by the novel heterogeneous Ziegler–Natta catalysts via one-pot strategy. The preparation of these catalysts involved the introduction of alkoxy silane compounds as electron donors. The influences of the electron donors structure, as well as polymerization conditions such as temperature, molar ratio of Al/Ti, ethylene pressure and the concentration of 1-hexene in feed on the polymerization performance for ethylene (co-)polymerization, were investigated. The morphology of the catalyst particles was characterized by SEM and Ti content of these catalysts was characterized by ICP. The GPC results showed that the obtained homopolyethylene and ethylene/1-hexene copolymer had the widest molecular weight distribution up to ca 50 when diethoxy-isopropoxy-(t–butoxy)-silane (ED3) was used as internal electron donor. The 13C NMR and FT-IR analysis indicated that these catalysts efficiently catalyzed the copolymerization of ethylene with 1-hexene.
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