Jizhu Jin

Synthesis and functionalization of poly(ethylene‐co‐dicyclopentadiene)

Copolymerizations of ethylene with endo-dicyclopentadiene (DCP) were performed by using Cp2ZrCl2 (Cp = Cyclopentadienyl), Et(Ind)2ZrCl2 (Ind = Indenyl), and Ph2C(Cp)(Flu)ZrCl2 (Flu = Fluorenyl) combined with MAO as cocatalyst. Among these three metallocenes, Et(Ind)2ZrCl2 showed the highest catalyst performance for the copolymerization. From 1H-NMR analysis, it was found that DCP was copolymerized through enchainment of norbornene rings. The copolymer was then epoxidated by reacting with m-chloroperbenzoic acid. 13C-NMR spectrum of the resulting copolymer indicated the quantitative conversion of olefinic to epoxy groups.

Ethene polymerization with a poly(styrene-co-divinylbenzene) beads supported rac-Ph2Si(Ind)2ZrCl2 catalyst

Poly(styrene-co-divinylbenzene) beads supported rac-Ph 2 Si(Ind) 2 ZrCl 2 was prepared and tested as a catalyst for ethene polymerization using methylaluminoxane (MAO) as a cocatalyst. At a polymerization temperature below 100°C, the catalyst showed pretty high activity to give polyethene beads replicating the shape of the carrier. With increasing polymerization temperature up to 150°C, the catalyst activity increased drastically but the spherical shape of polyethene disappeared due to the melting. From the plots of apparent activity against polymerization temperature, it was suggested that the polymerization below 100°C is more or less controlled by monomer diffusion through the crystalline polyethene films.

Alternating copolymerization of ethylene and propene with the [ethylene(1-indenyl)(9-fluorenyl)]zirconium dichloride-methylaluminoxane catalyst system

The copolymerization of ethylene and propene was conducted at −40°C with the [ethylene(1-indenyl)(9-fluorenyl)]zirconium dichloride-methylaluminoxane catalyst system, and the microstructure of the resulting copolymers was analyzed in detail by 13C NMR. The content of alternating [EP] sequences increased markedly with an increase in the feed ratio of propene to ethylene. A poly(ethylene-co-propene) with a proportion of [EP] sequences over 95% was thus obtained under appropriate copolymerization conditions. It was also demonstrated that the alternating ethylene-propene copolymer is stereoregular and isotactic.

Synthesis of polymer supported borate cocatalysts and their application to metallocene polymerizations

Polymer supported borate complexes were synthesized using poly(styrene-co-4-bromostyrene) and polystyrene-beads as carriers. These complexes were reacted with rac-Et[Ind]2ZrCl2 (Ind=indenyl) or Ph2C[(Cp)Flu]ZrCl2 (Cp=cyclopentadienyl, Flu=Fluorenyl) in toluene, at a molar ratio of [Zr]/[B]=1, to obtain polymer supported catalysts. Polymerizations of ethylene and propylene were conducted over them in the presence of Al(i-C4H9)3 as an activator. When poly(styrene-co-4-bromostyrene) was used as the carrier, the resulting soluble catalyst showed high activity comparable to those of the corresponding homogeneous catalysts for ethylene polymerization. For propylene polymerization, however, those catalysts showed low-activity. Even though the insoluble catalysts prepared with polystyrene-beads as carrier displayed far less activities for both ethylene and propylene polymerizations, it was found that the shape of polyethylene obtained at 40°C is a replica of the carrier particle.

Influences of methylaluminoxane separated by porous inorganic materials on the isospecific polymerization of propylene

Inorganic silicous porous materials such as MFI type zeolite, mesoporous silica MCM-41 and silica gel with different average pore diameters were applied to the adsorptive separation of methylaluminoxane (MAO) used as a cocatalyst in α-olefin polymerizations. The separated MAOs combined with rac-ethylene-(bisindenyl)zirconium dichloride (rac-Et(Ind) 2 ZrCl 2 ) were introduced to propylene polymerization, and their influences on the polymerization activity and stereoregularity of the resulting polymers were investigated. The polymerzation activity and isotactic [mmmm] pentad of the produced propylene were markedly dependent upon the pore size of the porous material used for adsorptive separation. From the results obtained from solvent extraction of the produced polymers, it was suggested that there are at least two kinds of active species with different stereospecificity in the rac-Et(Ind) 3 ZrCl 2 /MAO catalyst system.

Synthesis of isotactic poly(propylene) by titanium based catalysts containing diamide ligands

Propylene polymerization was carried out with [Ar (*) N(CH 2 ) 3 NAr (*) ]TiCl 2 (Ar = 2,6- i Pr 2 C 6 H 3 and Ar* = 2,6-Me 2 C 6 H 3 ) and [ArNCH 2 PhCH 2 NAr] TiCl 2 (Ar = 2,6- i Pr 2 C 6 H 3 ) complexes as catalysts. MAO and various combinations of trialkylaluminium and boron compounds as cocatalysts were employed to investigate the stereospecificity of the present catalysts system. Isotactic PP was obtained using [ArN(CH 2 ) 3 NAr]TiCl 2 and [ArNCH 2 Ph-CH 2 NAr]TiCl 2 (Ar = 2,6-iPr 2 C 6 H 3 ) complexes. It was newly found that even the polymerization with MAO as cocatalyst affords isotactic PP. It was confirmed that isotactic PP could be produced when R in the employed trialkylaluminium (AlR 3) became bulkier than an isobutyl group. The steric hindrance around the active metal center caused by the substituents in the ligand orbulky group in the bridge of the catalyst was found to play an important role for the sterospecificity of the present catalyst system.

Isospecific Propylene Polymerization Using the [ArN(CH2)3NAr]TiCl2/Al(iBu)3/Ph3CB(C6F5)4 Catalyst System in the Presence of Cyclohexene

Propylene polymerization was carried out using the [ArN(CH2)3NAr]TiCl2 (Ar = 2,6-iPr2C6H3)/Al(iBu)3/Ph3CB(C6F5)4 catalyst system in the presence of cyclohexene. It was found that isospecific polymerization is promoted by adding cyclohexene even at low propylene concentration. It was also indicated that a considerable number of isospecific active species retain the metal-polymer bond. Based on this fact, isotactic poly(propylene)-block-poly(1-hexene) could be obtained.

Copolymerization of 2-butene and ethylene with catalysts based on titanium and zirconium complexes

The polymerization of 2-butene and its copolymerization with ethylene have been investigated using four kinds of dichlorobis(β-diketonato)titanium complexes, [ArN(CH2)3NAr]TiCl2 (Ar = 2,6-iPr2C6H3) and typical metallocene catalysts. The obtained copolymers display lower melting points than those produced of homopolyethylene under the same polymerization conditions. 13C NMR analysis indicates that 9.3 mol-% of 2-butene units were incorporated into the polymer chains with Ti(BFA)2Cl2-MAO as the catalyst system. With the trans-2-butene a higher copolymerization rate was observed than with cis-2-butene. A highly regioselective catalyst system for propene polymerization, [ArN(CH2)3NAr]TiCl2 complex using a mixture of triisobutylaluminium and Ph3CB(C6F5)4 as cocatalyst, was found to copolymerize a mixture of 1-butene and trans-2-butene with ethylene up to 3.1 mol-%. Monomer isomerization-polymerization proceeds with typical metallocene catalysts to produce copolymers consisting of ethylene and 1-butene.

Synthesis of ethylene-α-olefin alternating copolymers with Et(1-Ind)(9-Flu)ZrCl2-MAO catalyst system

Copolymerizations of ethylene and o-olefins (4-methyl-1-pentene, 1-hevene, 1-decene and 1-hexadecene) were carried out with Et(1-Ind)(9-Flu)ZrCl 2 -MAO as the catalyst system. The degree of alternation in the resulting copolymers is higher than 92.1% for all the copolymers and close to 100% for ethylene-1-decene copolymer, Copolymerization behaviours focusing on the misinsertions during the polymerizations are investigated in detail from dyad and triad distributions estimated by 13 C NMR analysis of copolymers. A reactivity ratio, r E B , was obtained for ethylene-1-bexene copolymers using a simplified two sites alternating mechanics and found to be 8.7, which is the same order of that reported in ethylene-propene copolymerizations with Me 2 C(3-RCp)(Flu)-ZrCl 2 -MAO as the catalyst system.

Synthesis of terminally functionalized isotactic poly(propylene) with a [ArN(CH2)3NAr]TiCl2 (ar = 2,6-iPr2C6H3) - MAO catalyst system

Syntheses of terminally hydroxylated and iodinated isotactic poly(propylene)s were carried out by the reactions of oxygen and iodine with polymer-Al bonds produced in propylene polymerization with [ArN(CH 2 ) 3 -NAr]TiCl 2 (Ar = 2,6-Pr 2 C 6 H 3 ) combined with methylaluminoxane (MAO) as a cocatalyst. The resulting isotactic polymer (ca. 45 wt.-%) was separated from the atactic one by extraction with boiling ether. From 13 C NMR measurements of the isotactic fraction, it was found that the content of the terminally functionalized isotactic poly(propylene) was more than 80 mol-% in all cases.