• 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.

• Applied Chemistry for Engineering
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• v.29 no.4
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• pp.461-467
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• 2018

In this study, $(n-BuCp)_2ZrCl_2$, was supported on $SiO_2/MgCl_2$ binary support. Before supporting the catalyst, the $SiO_2/MgCl_2$ binary support was surface treated with three different alkyl aluminum compound, namely trimethylaluminum, triethylaluminum, and ethylaluminum sesquichloride. The synthesized surface-treated $SiO_2/MgCl_2$ supported metallocene catalysts were used for the copolymerization of ethylene and 1-hexene. Their catalytic properties and performances were analyzed through BET, XPS analysis, ICP-AES analysis, and FE-SEM. While the resulting copolymers were analyzed through DSC analysis, GPC analysis, 13C-NMR analysis, and FE-SEM. The analysis of synthesized surface-treated $SiO_2/MgCl_2$ supported metallocene catalysts showed that the Zr content of these catalysts is relatively lower compared to that of the catalyst supported on $SiO_2$. This could be attributed to the reduction in the surface area of $SiO_2$ due to the presence of recrystallized $MgCl_2$ and alkyl aluminum. Furthermore, they exhibited a better copolymerization activity compared to that of $SiO_2$ supported catalyst, particularly the EASC-surface treated binary support, which has the highest activity of 1.9 kg PE/($mmol-Zr^*hr$) because EASC acts as a strong Lewis acid. It could also be observed that the larger the ligand of alkyl aluminum used, the rougher the particle surface of the resulting polymer.

• Polymer(Korea)
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• v.24 no.4
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• pp.445-452
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• 2000

The copolymerization of ethylene (E) and norbornene (N) was examined by using various metallocene catalysts and modified-MAO(MMAO) cocatalyst. For $C_2$-symmetry catalysts such as rac-Et(Ind)$_2$ZrC $l_2$, M $e_2$Si(Ind)$_2$ZrC $l_2$, M $e_2$Si(Cp)$_2$ZrC $l_2$ and Cs-symmetrical iPr(FluCp)ZrC $l_2$ as well as CGC and di-bridged zirconocene, the effects of catalyst structure and [N]/[E] feed ratio on catalyst activity, thermal property and [N] content of copolymer (COC) was investigated. For rac-Et(Ind)$_2$ZrC $l_2$ catalyst of a constant [N]/[E] feed ratio, the appropriate conditions of [Al]/[Zr] mole ratio, polymerization temperature and cocatalyst structure were found to be 3000, 4$0^{\circ}C$, MMAO cocatalyst, respectively. As [N]/[E] feed ratio increased, the incorporation of norbornene to copolymer increased while, the activity of catalyst decreased except for iPr(FluCp)ZrC $l_2$ With consideration of catalyst activity as well as N content, it was found that rac-Et(Ind)$_2$ZrC $l_2$/MMAO system exhibited relatively high activity and controllable $T_{g}$. Monomer reactivity ratio was determined by Kelen-Tudos method..

• Polymer(Korea)
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• v.25 no.4
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• pp.468-475
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• 2001

For copolymerization of ethylene and norbornene initiated by various metallocene catalysts such as $rac-Et(Ind)_2ZrCl_2,\;rac-Me_2Si(Ind)_2ZrCl_2,\;rac-Me_2Si(Cp)_2ZrCl_2,\;and\;(n-BuCp)_2ZrCl_2$ with modified methylaluminoxane(MMAO) cocatalyst, the ${\alpha}$-olefins such as 1-hexene(H), 1-octene and 1-decene were added as a 3rd monomer. In this situation, the effects of the polymerization condition, the catalyst structure as well as the structure and the amount of added ${\alpha}$-olefin on the catalyst activity as well as the properties and structure of polymer were examined. As results, it was found that the catalyst activity and thermal property of polymer depended on not only catalyst structure but also ${\alpha}$-olefin structure. For $rac-Et(Ind)_2ZrCl_2/MMAO$ catalyst system, it was possible to get high activity and controllable $T_g$ of polymer. Among ${\alpha}$-olefins, H as a 3rd monomer exhibited the maximum enhancement in catalyst activity.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.229-232
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• 2006

Two novel synthetic route proposed for Hydro-Terminated Poly(EO-ran-THF) and tri-block(PEC-PTHF-PEG) copolymer by cationic ring-opening polymerization of tetrahydrofuran(THF) and ethylene oxide(EO) and just by polymerization of EO on poly-THF, respectively. Polyurethane was synthesized from random and tri-block HTPE using N-100/IPDI mixture as curing agent, and TPB(Triphenylbismuth) as catalyst. The mechanical properties of resultant polyurethane after mixing with various ratio of isocyanate was also investigated. Finally, the post treatment process of HTPE based on amount of catalyst used in the synthesis was studied, to evaluate the optimum curing condition for the polyurethane propellant binder.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.156-157
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• 2006

Quasi-living polymerization conditions for the copolymerization of ethylene and functionalized norbornenes can be achieved by using an initiator system comprising $[N-(2,6-diisopropylphenyl)-2-(2,6-diisopropylphenylimino)-propanamidato-{\kappa}^2N,O]Ni({\Box}^1-CH_2Ph)(PMe_3)\;and\;Ni(COD)_2$. It is possible with this polymerization system to obtain block-copolymer and tapered structures. The latter form microdomains similar to those of standard block co-polymers. The mechanism of the reaction will also be discussed.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.221-221
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• 2006

The stereochemical control in polypropylenes and styrene-ethylene copolymers based on homogeneous single-site polymerization catalysts has received great attention since the stereocpecificity is one of the key factors in tailoring the polymer properties. Thus, we have developed new tactics for isospecificity in propylene polymerization with the unbridged metallocenebased systems and syndiospecific styrene-styrene sequence in styrene-ethylene copolymerization with the group 4 metallocene system. Brief details of the synthesis, structures and the polymerization behavior of a set of new metallocene catalysts will be presented.

• Macromolecular Research
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• v.12 no.1
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• pp.100-106
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• 2004

We have prepared the polymethylene-bridged, dinuciear, half-sandwich constrained geometry catalysts (CGC)［Zr(η$\^$5/:η$^1$-C$\_$9/H$\_$5/SiMe$_2$NCMe$_3$)］$_2$［(CH$_2$)$\_$n/］［n=6(9), n=12(10)］by treating 2 equivalents of ZrCl$_4$with the corresponding tetralithium salts of the ligands in toluene. $^1$H and $\^$13/C NMR spectra of the synthesized complexes provide firm evidence for the anticipated dinuciear structure. In $^1$H NMR spectra, two singlets representing the methyl group protons bonded at the Si atom of the CGC are present at 0.88 and 0.64 ppm, which are considerably downfield positions relative to the shifts of 0.02 and 0.05 ppm of the corresponding ligands. To investigate the catalytic behavior of the prepared dinuciear catalysts, we conducted copolymerizations of ethylene and styrene in the presence of MMAO. The prime observation is that the two dinuclear CGCs 9 and 10 are not efficient for copo-lymerization, which definitely distinguishes them from the corresponding titanium-based dinuclear CGC. These species are active catalysts, however, for ethylene homopolymerization; the activity of catalyst 10, which contains a 12-methylene bridge, is larger than that of 9 (6-methylene bridge), which indicates that the presence of the longer bridge between the two active sites contributes more effectively to facilitate the polymerization activity of the dinuciear CGC. The activities increase as the polymerization temperature increases from 40 to 70$^{\circ}C$. On the other hand, the molecular weights of the polyethylenes are reduced when the polymerization temperature is increased. We observe that dinuciear metallocenes having different-length bridges give different polymerization results, which reconfirms the significant role that the nature of the bridging ligand has in controlling the polymerization properties of dinuclear catalysts.

• Journal of Integrative Natural Science
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• v.13 no.1
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• pp.13-18
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• 2020

This study used cerium iron hydroxide nanoparticle with HEMA (2-hydroxyethyl methacrylate), the cross-linker EGDMA (ethylene glycol dimethacrylate), NVP (N-vinyl-2-pyrrolidone) and the initiator AIBN (azobisisobutyronitrile) for copolymerization. Also, the physical properties of the prepared lenses were compared, and their applicability as polymers for ophthalmic materials was experimented. The results of the measurement showed that the UV blocking rate and the wettability increased with the cerium iron hydroxide nanoparticles addition ratio, and the refractive index and water content were not affected. Thus, the produced copolymer is expected to be useful as a functional contact lens material while satisfying the basic physical properties of the hydrogel contact lens.

• Journal of Radiation Industry
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• v.6 no.1
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• pp.49-54
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• 2012

Various anion exchange membranes were prepared by radiation graft copolymerization of vinylbenzyl chloride onto fluorinated films and subsequent quaternization with various tertiary amines such as trimethylamine, N,N-dimethylbuthylamine, N,N-dimethylaniline, and N-methylpiperidine. The quaternizations of the anion exchange membranes were confirmed by measuring of the ion exchange capacities of the membranes. The mechanical properties and the water uptakes were also measured. The elongation at break was found to be largely dependent on the fluorinated film, the quateranry ammonium, and the degree of grafting. The results indicate that the poly (ethylene-alt-tetrafluoroethylene) with quaternized trimethylamine moiety exhibits higher flexible property compared to the other prepared anion exchange membranes.