Diene comonomers bearing boronic acid masked with 1,8-diaminonaphthalene (dan) were applied to co... more Diene comonomers bearing boronic acid masked with 1,8-diaminonaphthalene (dan) were applied to copolymerization with isoprene or butadiene using neodymium borohydride complex as a catalyst. The comonomers were tolerant to excess modified methylaluminoxane (MMAO) and thus were applicable to the polymerization system using MMAO. On the other hand, the corresponding pinacol borate was highly reactive toward MMAO, and no incorporation into the obtained polymer was observed. A 13C NMR microstructural analysis of the hydrogenated copolymer revealed that all of the comonomers were located at the chain end. Further functionalization using the boron moiety at the polymer chain end was also investigated.
Copolymerization of ethylene with 1-hexene was carried out using two ansa-fluorenyl titanium deri... more Copolymerization of ethylene with 1-hexene was carried out using two ansa-fluorenyl titanium derivative complexes. The substituent effect on the catalytic activity, monomer reactivity ratio and polymer property was investigated. It was found that the presence of t-Bu groups on fluorenyl ring exhibited remarkable catalytic activity and produced polymer with high molecular weight. However, these catalysts produce polymer with narrow molecular weight distribution, indicating the characteristic of single-site metallocene catalyst. Based on 13C NMR, we can observe that monomer reactivity ratio was affected by catalyst structure. The rH values of complex 2 were lower than that of complex 1 which might be result from the higher steric hindrance leading to a reduction of 1- hexene insertion step.
In olefin polymerization using methylaluminoxane (MAO) as a cocatalyst, the remaining trialkylalu... more In olefin polymerization using methylaluminoxane (MAO) as a cocatalyst, the remaining trialkylaluminum (R 3 Al) in MAO sometimes leads to negative effects, such as a decrease in activity and molecular weight of the obtained polymer. Thus, in this study, the amount of R 3 Al in modified MAO (MMAO) was reduced by using a crosslinked terpolymer bearing bulky phenoxy groups as a solid support for R 3 Al. The R 3 Al removal efficiency of the terpolymer at a certain hydroxy group content was found to be much higher than that of SiO 2 , which has been previously reported to be an efficient R 3 Al remover. This is probably because of the steric bulkiness around the hydroxy groups and because some R 3 Al is physically adsorbed into the terpolymer. The chain transfer reaction derived from residual R 3 Al in propylene polymerization is mostly suppressed after the treatment of MMAO with the terpolymer.
A series of new fluorenylamido-ligated zirconium complexes bearing an electron-donating adamantyl... more A series of new fluorenylamido-ligated zirconium complexes bearing an electron-donating adamantyl group on the amido ligand were synthesized and characterized by elemental analysis, 1 H NMR, and single crystal X-ray analysis. The coordination mode of the fluorenyl ligand to the zirconium metal was η 3 manner, and all the complexes were C s-symmetric in solution. The complexes showed moderate activity (1.0 × 10 5 g-polymer mol-Zr −1 •h −1), even at a low Al/Zr ratio of 50. The increase of propylene pressure improved the activity by one order of magnitude (up to 1.0 × 10 6 g-polymer mol-Ti −1 •h −1). All catalyst systems gave syndiotactic polypropylene, where the complex containing the 3,6-di-t-butyl fluorenyl ligand was more effective for the enhancement of the syndiospecificity. The increase of propylene pressure also improved the syndiospecificity with the syndiotactic pentad of 0.96 and the melting point of 159 • C.
Poly(norbornene-co-styrene)s were synthesized by the use of anilinonaphthoquinone-ligated nickel ... more Poly(norbornene-co-styrene)s were synthesized by the use of anilinonaphthoquinone-ligated nickel complexes [Ni(C10H5O2NAr)(Ph)(PPh3): 1a, Ar = C6H3-2,6-iPr; 1b, Ar = C6H2-2,4,6-Me; 1c, Ar = C6H5] activated with modified methylaluminoxane (MMAO) or B(C6F5)3 in toluene. The effects of the cocatalysts were more significant than those of the nickel complexes, and MMAO gave higher activity than B(C6F5)3. The structural characterizations of the products indicated the formation of statistical norbornene copolymers. An increase of the styrene ratio in feed led to an increase in the incorporated styrene (S) content of the resulting copolymer. The molecular weight of the copolymer decreased with increasing the S ratio in feed at 70 °C. The copolymerization activity, using MMAO as a cocatalyst, decreased with lowering of the temperature from 70 to 0 °C, accompanied by an increase in the molecular weight of the copolymer. The S incorporation up to 59% with Mn of 78,000 was achieved by the 1b-B(...
The chain-walking polymerization of linear internal alkenes (i.e., trans-2-, 3-, and 4-octenes) u... more The chain-walking polymerization of linear internal alkenes (i.e., trans-2-, 3-, and 4-octenes) using αdiimine nickel catalysts activated with modified methylaluminoxane (MMAO) was studied in comparison with the corresponding terminal alkene polymerization. The rates of polymerization were found to decrease in the following order: 1-octene > 4-octene ≥ 2-octene ≫ 3-octene. The obtained branched poly(2-octene)s and poly(4-octene)s with high molecular weight and M w /M n less than 2 were amorphous polymers with low glass transition temperature (T g) of approximately −66°C. At 0°C, 4-octene polymerized in a living/controlled manner. The NMR analyses of the polymers showed that the chain-walking polymerization of 4-octene gave periodically branched polymers with the constant branching density, while that of 2-octene gave the polymer possessing fewer branches than the expected value due to monomerisomerization. The (n+2),(n+3)-and (n+3),(n+2)-insertions of the internal (n+2)-alkene [CH 3 (CH 2) n CHCH(CH 2) m CH 3 ] followed by chain-walking were confirmed by the 13 C NMR analysis of the produced polymers.
Propene polymerization with isotactic (iso)-specific C 2-symmetric rac-Me 2 Si(2-Me-Benz(e)-Ind) ... more Propene polymerization with isotactic (iso)-specific C 2-symmetric rac-Me 2 Si(2-Me-Benz(e)-Ind) 2 ZrCl 2 (1) and rac-Me 2 Si(2-Me-4-Ph-1-Ind) 2 ZrCl 2 (2) were conducted under various conditions for achieving iso-specific living polymerization of propene. When Complex 1 was activated with trialkylaluminum-free modified methylaluminoxane (dMMAO) at −40 • C, the number-average molecular weight (M n) linearly increased against the polymerization time to reach M n = 704,000 within 15 min of polymerization, although the molecular weight distributions was broad (M w /M n < 3). Thus, it was found that quasi-living polymerization of propene proceeded in the 1-dMMAO system. The living nature of iso-polypropene was confirmed by the block copolymerization, where the M n value increased from 221,000 to 382,000 after the addition of 1-octene to yield the block copolymer with a melting point of 150 • C.
A series of ansa-silylene(fluorenyl)(amido) titanium complexes (1a-1c, 2a, and 2b) bearing variou... more A series of ansa-silylene(fluorenyl)(amido) titanium complexes (1a-1c, 2a, and 2b) bearing various substituents on the amido and fluorenyl ligands are synthesized and characterized by elemental analysis, 1 H NMR, and single crystal X-ray analysis. The coordination mode of the fluorenyl ligand to the titanium metal is η 3 manner in each complex. The propylene polymerization is conducted with these complexes at 0 and 25 • C in a semi batch-type method, respectively. The catalytic activity of 1a-1c bearing cumyl-amido ligand is much higher than that of 2a and 2b bearing naphthyl group in amido ligand. High molecular weight polypropylenes are obtained with narrow molecular weight distribution, suggesting a living nature of these catalytic systems at 0 • C. The polymers produced are statistically atactic, regardless of the structure of the complex and the polymerization temperature.
A series of α-diimine Ni(II) complexes containing bulky phenyl groups, [ArN = C(Naphth)C = NAr]Ni... more A series of α-diimine Ni(II) complexes containing bulky phenyl groups, [ArN = C(Naphth)C = NAr]NiBr 2 (Naphth: 1,8-naphthdiyl, Ar = 2,6-Me 2-4-PhC 6 H 2 (C1); Ar = 2,4-Me 2-6-PhC 6 H 2 (C2); Ar = 2-Me-4,6-Ph 2 C 6 H 2 (C3); Ar = 4-Me-2,6-Ph 2 C 6 H 2 (C4); Ar = 4-Me-2-PhC 6 H 3 (C5); Ar = 2,4,6-Ph 3 C 6 H 2 (C6)), were synthesized and characterized. Upon activation with either diethylaluminum chloride (Et 2 AlCl) or modified methylaluminoxane (MMAO), all Ni(II) complexes showed high activities in ethylene polymerization and produced highly branched amorphous polyethylene (up to 145 branches/1000 carbons). Interestingly, the sec-butyl branches were observed in polyethylene depending on polymerization temperature. Polymerization of 1-alkene (1-hexene, 1-octene, 1-decene and 1-hexadecene) with C1-MMAO at room temperature resulted in branched polyolefins with narrow M w /M n values (ca. 1.2), which suggested a living polymerization. The polymerization results indicated the possibility of precise microstructure control, depending on the polymerization temperature and types of monomers.
ε-Caprolactone (CL) was polymerized by using N-methyldiethanolamine as an initiator followed by c... more ε-Caprolactone (CL) was polymerized by using N-methyldiethanolamine as an initiator followed by chain extension with hexamethylene diisocyanate afforded PCL-based poly(ester-urethane)s (PCLUs) with equally spaced tertiary amine groups. Treatment of the PCLUs with iodomethane converted tertiary amine groups to quaternary ammonium groups to give cationic ionomers. The thermal and mechanical properties of the obtained polymers were investigated.
In this work, the synthesis and the physical properties of poly(L-lactide-urethane)s (PLLAU) with... more In this work, the synthesis and the physical properties of poly(L-lactide-urethane)s (PLLAU) with ionic groups were studied. Using dimethylolpropionic acid (DMPA) as an initiator, L-lactide (L-LA) was polymerized in the presence of Sn(Oct)2 to give hydroxytelechelic PLLA (PLLA-diol) bearing a carboxy group at the center of the polymer chain. Chain extension of the in situ generated PLLA-diol with hexamethylene diisocyanate (HMDI) afforded PLLAU having equally separated carboxy groups. PLLAU was treated with various metal acetates to give ionomers, and their thermal and mechanical properties were investigated.
The two different kinds of impregnation (in situ and ex situ) were used in the heterogeneous copo... more The two different kinds of impregnation (in situ and ex situ) were used in the heterogeneous copolymerization of ethylene and 1-hexene for production of LLDPE/silica composite. For the ex situ impregnation, MMAO cocatalyst was immobilized firmly onto the silica support through washing and drying step before introducing the powder of MMAO/silica support into the copolymerization system. For the in situ impregnation, MMAO was only contacted with silica support for the short period of time before bringing all of the slurry of MMAO/silica support into the copolymerization system. By comparing the catalytic activity between two methods, it was found that the in situ impregnation provided the higher one beneficial from the lower interaction between MMAO and silica due to lower contacting time. The lower interaction enhanced the reactivity of MMAO toward zirconocene catalyst during activation process thus leading to the higher catalytic activity. The said interaction can be proven by thermal gravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) analysis. In addition, the obtained polymers were further characterized by means of scanning electron microscopy (SEM), 13 C-NMR spectroscopy (NMR) and differential scanning calorimetry (DSC).
This article reviews the living homopolymerization and copolymerization of propene, 1-alkene and ... more This article reviews the living homopolymerization and copolymerization of propene, 1-alkene and norbornene with ansadimethysilylene(fluorenyl)(amido)dimethyltitanium, Me 2 Si(g 3-C 13 H 8)(g 1-N t Bu)TiMe 2 and its derivatives, correlating the effects of cocatalysts, solvents, polymerization conditions and the substituents of the fluorenyl ligand with catalytic features, such as livingness, initiation efficiency, propagation rate, syndiospecificity and copolymerization ability. The synthesis of novel olefin block copolymers and their catalytic synthesis are also introduced using this living system.
Diene comonomers bearing boronic acid masked with 1,8-diaminonaphthalene (dan) were applied to co... more Diene comonomers bearing boronic acid masked with 1,8-diaminonaphthalene (dan) were applied to copolymerization with isoprene or butadiene using neodymium borohydride complex as a catalyst. The comonomers were tolerant to excess modified methylaluminoxane (MMAO) and thus were applicable to the polymerization system using MMAO. On the other hand, the corresponding pinacol borate was highly reactive toward MMAO, and no incorporation into the obtained polymer was observed. A 13C NMR microstructural analysis of the hydrogenated copolymer revealed that all of the comonomers were located at the chain end. Further functionalization using the boron moiety at the polymer chain end was also investigated.
Copolymerization of ethylene with 1-hexene was carried out using two ansa-fluorenyl titanium deri... more Copolymerization of ethylene with 1-hexene was carried out using two ansa-fluorenyl titanium derivative complexes. The substituent effect on the catalytic activity, monomer reactivity ratio and polymer property was investigated. It was found that the presence of t-Bu groups on fluorenyl ring exhibited remarkable catalytic activity and produced polymer with high molecular weight. However, these catalysts produce polymer with narrow molecular weight distribution, indicating the characteristic of single-site metallocene catalyst. Based on 13C NMR, we can observe that monomer reactivity ratio was affected by catalyst structure. The rH values of complex 2 were lower than that of complex 1 which might be result from the higher steric hindrance leading to a reduction of 1- hexene insertion step.
In olefin polymerization using methylaluminoxane (MAO) as a cocatalyst, the remaining trialkylalu... more In olefin polymerization using methylaluminoxane (MAO) as a cocatalyst, the remaining trialkylaluminum (R 3 Al) in MAO sometimes leads to negative effects, such as a decrease in activity and molecular weight of the obtained polymer. Thus, in this study, the amount of R 3 Al in modified MAO (MMAO) was reduced by using a crosslinked terpolymer bearing bulky phenoxy groups as a solid support for R 3 Al. The R 3 Al removal efficiency of the terpolymer at a certain hydroxy group content was found to be much higher than that of SiO 2 , which has been previously reported to be an efficient R 3 Al remover. This is probably because of the steric bulkiness around the hydroxy groups and because some R 3 Al is physically adsorbed into the terpolymer. The chain transfer reaction derived from residual R 3 Al in propylene polymerization is mostly suppressed after the treatment of MMAO with the terpolymer.
A series of new fluorenylamido-ligated zirconium complexes bearing an electron-donating adamantyl... more A series of new fluorenylamido-ligated zirconium complexes bearing an electron-donating adamantyl group on the amido ligand were synthesized and characterized by elemental analysis, 1 H NMR, and single crystal X-ray analysis. The coordination mode of the fluorenyl ligand to the zirconium metal was η 3 manner, and all the complexes were C s-symmetric in solution. The complexes showed moderate activity (1.0 × 10 5 g-polymer mol-Zr −1 •h −1), even at a low Al/Zr ratio of 50. The increase of propylene pressure improved the activity by one order of magnitude (up to 1.0 × 10 6 g-polymer mol-Ti −1 •h −1). All catalyst systems gave syndiotactic polypropylene, where the complex containing the 3,6-di-t-butyl fluorenyl ligand was more effective for the enhancement of the syndiospecificity. The increase of propylene pressure also improved the syndiospecificity with the syndiotactic pentad of 0.96 and the melting point of 159 • C.
Poly(norbornene-co-styrene)s were synthesized by the use of anilinonaphthoquinone-ligated nickel ... more Poly(norbornene-co-styrene)s were synthesized by the use of anilinonaphthoquinone-ligated nickel complexes [Ni(C10H5O2NAr)(Ph)(PPh3): 1a, Ar = C6H3-2,6-iPr; 1b, Ar = C6H2-2,4,6-Me; 1c, Ar = C6H5] activated with modified methylaluminoxane (MMAO) or B(C6F5)3 in toluene. The effects of the cocatalysts were more significant than those of the nickel complexes, and MMAO gave higher activity than B(C6F5)3. The structural characterizations of the products indicated the formation of statistical norbornene copolymers. An increase of the styrene ratio in feed led to an increase in the incorporated styrene (S) content of the resulting copolymer. The molecular weight of the copolymer decreased with increasing the S ratio in feed at 70 °C. The copolymerization activity, using MMAO as a cocatalyst, decreased with lowering of the temperature from 70 to 0 °C, accompanied by an increase in the molecular weight of the copolymer. The S incorporation up to 59% with Mn of 78,000 was achieved by the 1b-B(...
The chain-walking polymerization of linear internal alkenes (i.e., trans-2-, 3-, and 4-octenes) u... more The chain-walking polymerization of linear internal alkenes (i.e., trans-2-, 3-, and 4-octenes) using αdiimine nickel catalysts activated with modified methylaluminoxane (MMAO) was studied in comparison with the corresponding terminal alkene polymerization. The rates of polymerization were found to decrease in the following order: 1-octene > 4-octene ≥ 2-octene ≫ 3-octene. The obtained branched poly(2-octene)s and poly(4-octene)s with high molecular weight and M w /M n less than 2 were amorphous polymers with low glass transition temperature (T g) of approximately −66°C. At 0°C, 4-octene polymerized in a living/controlled manner. The NMR analyses of the polymers showed that the chain-walking polymerization of 4-octene gave periodically branched polymers with the constant branching density, while that of 2-octene gave the polymer possessing fewer branches than the expected value due to monomerisomerization. The (n+2),(n+3)-and (n+3),(n+2)-insertions of the internal (n+2)-alkene [CH 3 (CH 2) n CHCH(CH 2) m CH 3 ] followed by chain-walking were confirmed by the 13 C NMR analysis of the produced polymers.
Propene polymerization with isotactic (iso)-specific C 2-symmetric rac-Me 2 Si(2-Me-Benz(e)-Ind) ... more Propene polymerization with isotactic (iso)-specific C 2-symmetric rac-Me 2 Si(2-Me-Benz(e)-Ind) 2 ZrCl 2 (1) and rac-Me 2 Si(2-Me-4-Ph-1-Ind) 2 ZrCl 2 (2) were conducted under various conditions for achieving iso-specific living polymerization of propene. When Complex 1 was activated with trialkylaluminum-free modified methylaluminoxane (dMMAO) at −40 • C, the number-average molecular weight (M n) linearly increased against the polymerization time to reach M n = 704,000 within 15 min of polymerization, although the molecular weight distributions was broad (M w /M n < 3). Thus, it was found that quasi-living polymerization of propene proceeded in the 1-dMMAO system. The living nature of iso-polypropene was confirmed by the block copolymerization, where the M n value increased from 221,000 to 382,000 after the addition of 1-octene to yield the block copolymer with a melting point of 150 • C.
A series of ansa-silylene(fluorenyl)(amido) titanium complexes (1a-1c, 2a, and 2b) bearing variou... more A series of ansa-silylene(fluorenyl)(amido) titanium complexes (1a-1c, 2a, and 2b) bearing various substituents on the amido and fluorenyl ligands are synthesized and characterized by elemental analysis, 1 H NMR, and single crystal X-ray analysis. The coordination mode of the fluorenyl ligand to the titanium metal is η 3 manner in each complex. The propylene polymerization is conducted with these complexes at 0 and 25 • C in a semi batch-type method, respectively. The catalytic activity of 1a-1c bearing cumyl-amido ligand is much higher than that of 2a and 2b bearing naphthyl group in amido ligand. High molecular weight polypropylenes are obtained with narrow molecular weight distribution, suggesting a living nature of these catalytic systems at 0 • C. The polymers produced are statistically atactic, regardless of the structure of the complex and the polymerization temperature.
A series of α-diimine Ni(II) complexes containing bulky phenyl groups, [ArN = C(Naphth)C = NAr]Ni... more A series of α-diimine Ni(II) complexes containing bulky phenyl groups, [ArN = C(Naphth)C = NAr]NiBr 2 (Naphth: 1,8-naphthdiyl, Ar = 2,6-Me 2-4-PhC 6 H 2 (C1); Ar = 2,4-Me 2-6-PhC 6 H 2 (C2); Ar = 2-Me-4,6-Ph 2 C 6 H 2 (C3); Ar = 4-Me-2,6-Ph 2 C 6 H 2 (C4); Ar = 4-Me-2-PhC 6 H 3 (C5); Ar = 2,4,6-Ph 3 C 6 H 2 (C6)), were synthesized and characterized. Upon activation with either diethylaluminum chloride (Et 2 AlCl) or modified methylaluminoxane (MMAO), all Ni(II) complexes showed high activities in ethylene polymerization and produced highly branched amorphous polyethylene (up to 145 branches/1000 carbons). Interestingly, the sec-butyl branches were observed in polyethylene depending on polymerization temperature. Polymerization of 1-alkene (1-hexene, 1-octene, 1-decene and 1-hexadecene) with C1-MMAO at room temperature resulted in branched polyolefins with narrow M w /M n values (ca. 1.2), which suggested a living polymerization. The polymerization results indicated the possibility of precise microstructure control, depending on the polymerization temperature and types of monomers.
ε-Caprolactone (CL) was polymerized by using N-methyldiethanolamine as an initiator followed by c... more ε-Caprolactone (CL) was polymerized by using N-methyldiethanolamine as an initiator followed by chain extension with hexamethylene diisocyanate afforded PCL-based poly(ester-urethane)s (PCLUs) with equally spaced tertiary amine groups. Treatment of the PCLUs with iodomethane converted tertiary amine groups to quaternary ammonium groups to give cationic ionomers. The thermal and mechanical properties of the obtained polymers were investigated.
In this work, the synthesis and the physical properties of poly(L-lactide-urethane)s (PLLAU) with... more In this work, the synthesis and the physical properties of poly(L-lactide-urethane)s (PLLAU) with ionic groups were studied. Using dimethylolpropionic acid (DMPA) as an initiator, L-lactide (L-LA) was polymerized in the presence of Sn(Oct)2 to give hydroxytelechelic PLLA (PLLA-diol) bearing a carboxy group at the center of the polymer chain. Chain extension of the in situ generated PLLA-diol with hexamethylene diisocyanate (HMDI) afforded PLLAU having equally separated carboxy groups. PLLAU was treated with various metal acetates to give ionomers, and their thermal and mechanical properties were investigated.
The two different kinds of impregnation (in situ and ex situ) were used in the heterogeneous copo... more The two different kinds of impregnation (in situ and ex situ) were used in the heterogeneous copolymerization of ethylene and 1-hexene for production of LLDPE/silica composite. For the ex situ impregnation, MMAO cocatalyst was immobilized firmly onto the silica support through washing and drying step before introducing the powder of MMAO/silica support into the copolymerization system. For the in situ impregnation, MMAO was only contacted with silica support for the short period of time before bringing all of the slurry of MMAO/silica support into the copolymerization system. By comparing the catalytic activity between two methods, it was found that the in situ impregnation provided the higher one beneficial from the lower interaction between MMAO and silica due to lower contacting time. The lower interaction enhanced the reactivity of MMAO toward zirconocene catalyst during activation process thus leading to the higher catalytic activity. The said interaction can be proven by thermal gravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) analysis. In addition, the obtained polymers were further characterized by means of scanning electron microscopy (SEM), 13 C-NMR spectroscopy (NMR) and differential scanning calorimetry (DSC).
This article reviews the living homopolymerization and copolymerization of propene, 1-alkene and ... more This article reviews the living homopolymerization and copolymerization of propene, 1-alkene and norbornene with ansadimethysilylene(fluorenyl)(amido)dimethyltitanium, Me 2 Si(g 3-C 13 H 8)(g 1-N t Bu)TiMe 2 and its derivatives, correlating the effects of cocatalysts, solvents, polymerization conditions and the substituents of the fluorenyl ligand with catalytic features, such as livingness, initiation efficiency, propagation rate, syndiospecificity and copolymerization ability. The synthesis of novel olefin block copolymers and their catalytic synthesis are also introduced using this living system.
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Papers by Takeshi SHIONO