• Polymer(Korea)
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• v.35 no.1
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• pp.77-86
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• 2011

Polymerization properties of six dinuclear constrained geometry catalysts (DCGC) were investigated. The different length bridges of three catalysts were para-phenyl (Catalyst 1), para-xylyl (Catalyst 2), and para-diethylene phenyl (Catalyst 6). The other three DCGC have the same para-xylyl bridge with the different substituents at the phenyl ring of the bridge. The selected substituents were isopropyl (Catalyst 3), n-hexyl (Cataylst 4), and n-octyl (Catalyst 5), It was found that the longer catalyst not only exhibited a greater activity but also prepared a higher molecular weight copolymer. The catalyst 3 having a bulky isopropyl substituent revealed the lower activity but formed the highest molecular weight polymer comparing with the other alkyl substituted DCGCs. These results were able to be understood on the basis of the electronic and steric characteristics of the bridge. This study confirms that the control of the bridge structure of DCGC may contribute to control the microstructure of polymers.

• Elastomers and Composites
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• v.48 no.4
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• pp.263-268
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• 2013

In this study, we prepared poly(ethylene-ter-1-hexene-ter-divinylbenzene) using bridged rac-$Et[Ind]_2ZrCl_2$ metallocene catalysts. The effect of 1-hexene on the terpolymerization rate was evaluated. When cocatalyst/catalyst molar ratio was 3,000, catalytic activity indicated more than 8,000 which was very remarkable value. As polymerization time increased, the weight-average molecular weight of the terpolymer gradually increased to some degree. In case of a polymerization time of 50 minutes, the terpolymer became amorphous state. The molecular weight distribution and densities of the terpolymer were 110,000-200,000 and $0.85-0.89g/cm^3$, respectively. Thermal properties and structure of the terpolymer were also identified.

• Polymer(Korea)
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• v.24 no.6
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• pp.751-756
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• 2000

The copolymerization of ethylene (E) and cycloolefin (CO) was carried out with rac-Et(Ind)$_2$ZrC $l_2$ and MMAO cocatalyst system to examine the effect of CO structure on catalytic behaviors and properties of copolymer (COC). Various cycloolefins such as norbornene (N), 5-phenyl-2-norbornene (PN) and 5-vinyl-2-norbornene (VN) were used as comonomers. With increasing [CO]/[E] feed ratio, the catalytic activity decreased while the glass transition temperature of copolymer increased. With analysis of the structure of E/VN copolymer by FT-IR and $^{l3}$C-NMR, it was found that the cyclic C=C bond of VN comonomer is selectively polymerized and the vinyl C=C bond remains unreacted. The resulting vinyl C=C bond attached into copolymer provided the functionalization moiety using glycidyl methacrylate.e.

• Korean Chemical Engineering Research
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• v.53 no.3
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• pp.397-400
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• 2015

The effects of surface treatment method of unreacted N-[3-(trimethoxysilyl)propyl]ethylenediamine (2NS), $N^1$-(3-trimethoxysilylpropyl)diethylenetriamine (3NS), and 3-cyanopropyltriethoxysilane (1NCy) after grafting on the surface of silica and of the surface treatment temperature on ethylene polymerization were investigated. The Zr content of supported catalyst employing filtering method was higher than that of washing method, and the activities of supported catalysts prepared by washing method were higher than those of filtering methods significantly. Regardless of surface treatment methods the activities were in order by $SiO_2/2NS/(n-BuCp)_2ZrCl_2>SiO_2/1NCy/(n-BuCp)_2ZrCl_2>SiO_2/3NS/(n-BuCp)_2ZrCl_2$. The ethylene polymerization activity was increased as the surface treatment temperature of aminosilane on silica increased.

• Applied Chemistry for Engineering
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• v.10 no.6
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• pp.944-948
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• 1999

The morphological properties of four binary blends of polyethylene synthesized by metallocene catalyst(MCPE) and four polyolefins prepared by Ziegler-Natta catalyst have been investigated to interpret the effect of micro-molecular structure on the phase morphology and interfacial behavior; four binary blend systems studied are high density polyethylene(HDPE)-metallocene polyethylene (MCPE), polypropylene(PP)-MCPE, poly(propylene-co-ethylene) (CoPP)-MCPE, and poly(propylene-co-ethylene-co-1-butylene) (TerPP)-MCPE, and they are all phase separated. The HDPE-MCPE blend shows evenly growing homogeneous HDPE domain on the continuous MCPE phase, on the other hand, the rest of three blends show complex heterogeneous phase behavior. The PP-MCPE blend shows that PP and MCPE and completely phase separated and phase inversion takes place at 50% MCPE. The CoPP-MCPE and TerPP-MCPE show enhanced interface due to the same micro-molecular structure of ethylene, and phase inversion takes place at 40% MCPE. In particular, TerPP-MCPE blend shows improved phase morphology between interfaces, and this may be arisen from the comonomer contents in TerPP, which are 1-butene and ethylene having the same chemical structure as that of MCPE. The enhancement of the phase morphology in the TerPP-MCPE blend is correlated with the mechanical and morphological properties. Thus, although the four blend systems are phase separated, the phase morphology suggests that the order of interfacial adhesion strength be HDPE-MCPE > TerPP-MCPE > CoPP-MCPE > PP-MCPE and that micro-molecular structure between constituents be one of major factors giving enhanced interfacial adhesion.

• Journal of Integrative Natural Science
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• v.6 no.1
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• pp.34-38
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• 2013

Tributyltin hydride ($n-Bu_3SnH$), an endocrine disruptor, was slowly polymerized by the group 4 ${Cp^{\prime}}_2TiCl_2/N$-selectride (Cp' = $C_5H_5$, Cp; $Me-C_5H_4$, Me-Cp; $Me_5C_5$, $Cp^*$) catalyst combination to give two phases of products: one is an insoluble cross-linked solid, polystannane in 3-25% yield as minor product via disproportionation/dehydrocoupling combination process, and the other is an oil, hexabutyldistannane in 65-90% yield as major product via simple dehydrocoupling process. Disproportionation/dehydrocoupling process first produced a low-molecular-weight oligostannane possessing partial backbone Sn-H bonds which then underwent an extensive cross-linking reaction of backbone Sn-H bonds, resulting in the formation of an insoluble polystannane. The disproportionation/dehydrocoupling of a tertiary hydrostannane mediated by early transition metallocene/inorganic hydride is quite unusual and applicable.

• Macromolecular Research
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• v.15 no.5
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• pp.430-436
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• 2007

The dinuclear half-sandwich CGCs (constrained geometry catalyst) with a polymethylene bridge, $[Ti({\eta}^5 : {\eta}^1-indenyl)SiMe_2NCMe_3]_2(CH_2)_n]$[n = 6 (1) and 12 (2)], have been employed in the copolymerization of ethylene and norbornene (NBE). To compare the mononuclear metallocene catalysts; $Ti({\eta}^5 : {\eta}^1-2-hexylindenyl)SiMe_2NCMe_3$ (3), $(Cp^* SiMe_2NCMe_3)$Ti (Dow CGC) (4) and ansa-$Et(Ind)_2ZrCI_2$ (5), were also studied for the copolymerization of ethylene and NBE. It was found that the activity increased in the order: 1 < 2 < 3 < 5 < 4, indicating that the presence of the bridge between two the CGC units contributed to depressing the polymerization activity of the CGCs. This result strongly suggests that the implication of steric disturbance due to the presence of the bridge may playa significant role in slowing the activity. Dinuclear CGCs have been found to be very efficient for the incorporation of NBE onto the polyethylene backbone. The NBE contents in the copolymers formed ranged from 10 to 42%, depending on the polymerization conditions. Strong chemical shifts were observed at ${\delta}$42.0 and 47.8 of the isotactic alternating NBE sequences, NENEN, in the copolymers with high NBE contents. In addition, a resonance at 47.1 ppm for the sequences of the isolated NBE, EENEE, was observed in the $^{13}C-NMR$ spectra of the copolymers with low NBE contents. The absence of signals for isotactic dyad at 48.1 and 49.1 ppm illustrated there were no isotactic or microblock (NBE-NBE) sequences in the copolymers. This result indicated that the dinuclear CGCs were effective for making randomly distributed ethylene-NBE copolymers.

• Polymer(Korea)
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• v.31 no.6
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• pp.497-504
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• 2007

We have prepared the dinuclear half-sandwich CGC(constrained geometry catalyst) with polymethylene bridge $[Zr(({\eta}^5\;:\;{\eta}^1-C_9H_5SiMe_2NCMe_3)Me_2)_2\;[(CH_2)_n]$ [n=6(4), 9(5), 12(6)] by treating 2 equivalents of MeLi with the corresponding dichlorides compounds. To study the catalytic behavior of the dinuclear catalysts we conducted copolymerization of ethylene and 1-hexene in the presence of three kinds of boron cocatalysts, $Ph_3C^+[B(C_6F_5)_4]^-\;(B_1),\;B(C_6F_5)_3\;(B_3)$, and $Ph_3C^+[(C_6F_5)_3B-C_6F_4-B(C_6F_5)_3]^{2-}\;(B_2)$. It turned out that all active species formed by the combination of three dinuclear CGCs with three cocatalyst were very efficient catalysts for the polymerization of olefins. The activities increase as the bridge length of the dinuclear CGCs increases. At the same time the dinuclear cocatalyst exhibited the lowest activity among three cocatalysts. The prime observation is that the dinuclear cocatalyst gave rise to the formation of the copolymers with the least branches on the polyethylene backbone.

• Macromolecular Research
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• v.10 no.2
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• pp.97-102
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• 2002

The mixtures of non-conjugated dienes, 4-methyl-1,4-hexadiene and 5-methyl-1,4-hexadiene (MHD), were successfully synthesized by the reaction of isoprene with ethylene using Fe(III)-based catalyst in toluene. The conversion was over 96 mol% on the basis of the initial amount of isoprene used. The production yield for MHD was nearly 50 mol%, the other was polyisoprene. The mixtures were successfully copolymerized with ethylene by using zirconium-based metallocenes. The products were characterized by the combinations of gas chromatography, high temperature gel permeation chromatography, $^1$H NMR, $^{13}$ C NMR, high temperature $^1$H NMR, UV/visible spectroscopy, and differential scanning calorimetry. It was found that 5-methyl-1,4-hexadiene was active enough to be incorporated into the copolymer chain but the corresponding isomeric material,4-methyl-1,4-hexadiene, was inactive in metallocene-catalyzed copolymerizations. Specifically, in the zirconocene-catalyzed copolymerizations of ethylene with MHD, ansa-structure catalysts seem to be more efficient than non-bridged type zirconocene. The degree of incorporation of MHD in the resulting copolymers was able to be controlled by the amount of non-conjugated dienes used initially.

• Polymer(Korea)
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• v.24 no.5
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• pp.646-655
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• 2000

Polymerizations of higher $\alpha$-olefins were carried out in toluene by using highly isospecific catalyst, rac-(EBI)M(NMe$_2$)$_2$ (EBI=1,2-ethylenebis-(1-indenyl); M=Zr(rac-1); M=Hf(rac-2)) In the presence of Al(i-Bu)$_3$/[Ph$_3$C][B($C_{6}F_{5}$)$_4$]. The polymerization of high $\alpha$-olefin showed high activity and similar polymerization behavior. The polymerization activity was affected by both monomer size and lateral size of polymer chain. The conversion of monomer to polymer decreases with the increased lateral size in the order of 1-pentene>1-hexene>1-octene>1-decene. The same dependences of melting behavior and intrinsic viscosity of polyolefin on lateral size were observed according to the results obtained by differential scanning calorimetry and intrinsic viscosity. All poly($\alpha$-olefin)s showed very high isotacticity (triad) and the isotacticity increases in the order of poly(1-pentene)$^1H$ NMR and Raman spectra analysis showed that chain transfer to cocatalyst, which generates saturated methyl groups, Is a main chain termination. The $\beta$-hydride eliminations, which generate unsaturated vinylidene, tri-substituted, and vinylene end group. are found to be minor chain terminations.