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Synthesis and Characterization of Aliphatic Polyether Dendrons Based on Polystyrene Peripheries
Jie Song,Hyun-Yu Kim,Byoung-Ki Cho* 대한화학회 2007 Bulletin of the Korean Chemical Society Vol.28 No.10
The synthesis of well-defined dendrons based on aliphatic polyether dendritic cores and glassy polystyrene peripheries is described. The synthetic route involves a combination of living anionic polymerization and a stepwise convergent method consisting of iterative Williamson etherification and hydroboration/oxidation reactions. On the basis of molecular weight, as characterized by gel permeation chromatography (GPC), the first generation dendron (Generation-1) shows a random coil conformation like a linear polystyrene, while higher generations (Generation-2 and 3) reveal globular forms in solution.
The effect of a reinforcement phase on the oxidation mechanism of ZrB2-YAG-Al2O3 ceramcis
Jie-Guang Song,Fang Wang,Ming-Han Xu,Shi-Bin Li,Gang-Chang Ji 한양대학교 세라믹연구소 2012 Journal of Ceramic Processing Research Vol.13 No.3
ZrB2 and YAG are widely applied because of some excellent properties, but ZrB2 is easily oxidized in high-temperature air. To make ZrB2 ceramics have a better oxidation resistance, high-density ZrB2-YAG-Al2O3 ceramics were prepared. The effect of a reinforcement phase on the oxidation mechanism of ZrB2-YAG-Al2O3 ceramics is investigated at different high temperature ranges. The results show that the overall tendency of the weight gain of ZrB2-YAG ceramics and ZrB2 ceramics are similar, but the weight gain of ZrB2-YAG ceramics is less than that of ZrB2 ceramics. The weight gain tendency of three types of ceramics are similar below 1000, the weight gain of ZrB2-YAG and ZrB2-YAG-Al2O3 ceramics have a mild tendency between 1000 and 1300, the weight gain tendency of ZrB2-YAG ceramics and ZrB2 ceramics are similar at 1300, however, the weight gain tendency of ZrB2-YAG-Al2O3 ceramics became mild at 1300 due to the Al18B4O33 coating on the ceramic surface. The weight gain rapidly increased for 1h, then the weight gain tendency became mild after 1 h. The weight gain tendency of ZrB2-YAG-Al2O3 ceramics is similar by contrast with ZrB2-YAG ceramics and ZrB2 ceramics for 1 h, the weight gain tendency of ZrB2-YAG-Al2O3 ceramics is extremely mild at a higher oxidation temperature after 1 h. ZrB2 and YAG are widely applied because of some excellent properties, but ZrB2 is easily oxidized in high-temperature air. To make ZrB2 ceramics have a better oxidation resistance, high-density ZrB2-YAG-Al2O3 ceramics were prepared. The effect of a reinforcement phase on the oxidation mechanism of ZrB2-YAG-Al2O3 ceramics is investigated at different high temperature ranges. The results show that the overall tendency of the weight gain of ZrB2-YAG ceramics and ZrB2 ceramics are similar, but the weight gain of ZrB2-YAG ceramics is less than that of ZrB2 ceramics. The weight gain tendency of three types of ceramics are similar below 1000, the weight gain of ZrB2-YAG and ZrB2-YAG-Al2O3 ceramics have a mild tendency between 1000 and 1300, the weight gain tendency of ZrB2-YAG ceramics and ZrB2 ceramics are similar at 1300, however, the weight gain tendency of ZrB2-YAG-Al2O3 ceramics became mild at 1300 due to the Al18B4O33 coating on the ceramic surface. The weight gain rapidly increased for 1h, then the weight gain tendency became mild after 1 h. The weight gain tendency of ZrB2-YAG-Al2O3 ceramics is similar by contrast with ZrB2-YAG ceramics and ZrB2 ceramics for 1 h, the weight gain tendency of ZrB2-YAG-Al2O3 ceramics is extremely mild at a higher oxidation temperature after 1 h.
Jie Song,Pu Su Zhao,Guang Zhang 대한화학회 2010 Bulletin of the Korean Chemical Society Vol.31 No.7
A dicycle pyrazoline derivative, 1-phenyl-5-(p-fluorophenyl)-3,4-(α-p-fluoro-tolylenecyclohexano) pyrazoline, was synthesized and characterized by elemental analysis, IR, UV-vis, fluorescence spectra and X-ray single crystal diffraction. Density function theory (DFT) calculations were performed by using B3LYP method with 6-311G** basis set. The optimized geometry can well simulate the molecular structure. Vibrational frequencies were predicted, assigned and compared with the experimental values, which suggest that B3LYP/6-311G** method can well predict the IR spectra. Both the experimental electronic absorption spectra and the predicted ones by B3LYP/6-311G** method reveal three electron-transition bands, with the theoretical ones having some red shifts compared with the experimental data. Natural bond orbital analyses indicate that the absorption bands are mainly derived from the contribution of n → π* and π → π*transitions. Fluorescence spectra determination shows that the title compound can emit blue-light at about 478 nm. On the basis of vibrational analysis, the thermodynamic properties of title compound at different temperature have been calculated,revealing the correlations between C0p, m, S0m, H0m and temperature.
Effect of the sintering technology on the properties of fired brick from quartz sands
Jie-Guang Song,Fang Wang,Xiao-Bo Bai,Da-Ming Du,Yin-Yan Ju,Ming-Han Xu,Gang-Chang Ji 한양대학교 세라믹연구소 2011 Journal of Ceramic Processing Research Vol.12 No.4
River sands as low grade natural raw materials are used to prepare the fired brick to replace clay fired bricks, which aims to save land resources and use low grade natural resources to realize high cost performance. In this paper, the effect of sintering technology of bricks on their performance is discussed. The compressive strength of fired bricks is first increased and then decreased with an increase in the sintering temperature, the compressive strength of bricks prepared by the isostatic compaction shaping is higher than that of bricks prepared by the plastic shaping under the same conditions. The compressive strength of bricks reaches 28 MPa when sintered at 1150 oC by using a 20MPa isostatic compaction shaping method. The compressive strength of bricks is first increased and then decreased by prolonging the holding time, the compressive strength of bricks reaches 28.9MPa when sintered at 1150 oC for 2 h.
Jie Song,Byoung-Ki Cho* 대한화학회 2008 Bulletin of the Korean Chemical Society Vol.29 No.6
We investigated the glass transition temperatures (Tg) of dendrons consisting of conformationally mobile aliphatic polyether dendritic cores plus glassy peripheral polystyrenes (PSs), and linear PSs in the molecular weight range of 1000-8500 g/mol. We compared their Tg behavior depending on their polymeric architecture. The linear PSs show a typical growth of Tg up to 92.5℃ as the molecular weight increases to 8300 g/mol, while the dendrons display nearly constant Tg values of 58-61℃, despite the increase of molecular weight with each generation. The striking contrast of Tg behavior would be mainly attributed to the fact that the dendrons keep the ratio of Ne/M (Ne: number of peripheral chain ends, M: molecular weight) over all the generations. Additionally, for the influence of dendritic spacers on glass transition temperature we prepared dimeric PSs with different linkage groups such as aliphatic ether, ester and amide bonds. We found that the dimer with the ether spacer exhibited the lowest glass transition at 55.4℃, while the amide linked dimer showed the highest glass transition temperature at 74.2℃. This indicates that the peripheral PS chains are effectively decoupled by the conformationally flexible ether spacer. The results from this study demonstrated that polymeric architecture and dendritic core structures play a crucial role in the determination of glass transition behavior, providing a strategy for the systematic engineering of polymer chain mobility.
Oxidation behavior of YAG-ZrB2 ceramics prepared by spark plasma sintering
Jie-Guang Song,Da-Ming Du,Yin-Yan Ju,Yang-Liang Li,Shi-Bin Li,Gang-Chang Ji 한양대학교 세라믹연구소 2010 Journal of Ceramic Processing Research Vol.11 No.4
ZrB2 and YAG are widely applied because of some excellent properties, but ZrB2 is easily oxidized in high-temperature air. To make ZrB2 ceramics have better oxidation resistance, high-density YAG-ZrB2 ceramics were prepared. The oxidation behavior of YAG-ZrB2 ceramics is investigated at different temperatures. The results indicate that the enhanced weight change differs according to the temperature range, slightly in the temperature 900-1000oC, sharply from 1100-1300 and smoothly above 1300oC. The weight change rate of YAG-ZrB2 ceramics is increased by prolonging the oxidation time, but the weight change rate of YAG-ZrB2 ceramics is gradually reduced. The oxidation layer is porous as compared to the YAG-ZrB2 ceramics layer.