Monomer-isomerization polymerization. XXIII.. Monomer-isomerization polymerization of 5-phenyl-2-pentene with ziegler–natta catalysts

5-Phenyl-2-pentene (5Ph2P) was found to undergo monomer-isomerization polymerization with TiCl₃–R₃Al (R = C₂H₅ or i-C₄H₉, Al/Ti > 2) catalysts to give a polymer consisting of exclusively 5-phenyl-1-pentene (5Ph1P) unit. The geometric and positional isomerizations of 5Ph2P to its terminal and other internal isomers were observed to occur during polymerization. The catalyst activity of alkylaluminum examined to TiCl₃ was in the following order: (C₂H₅)₃Al > (i-C₄H₉)₃Al > (C₂H₅)₂AlCl. The rate of monomer-isomerization polymerization of 5Ph2P with TiCl₃–(C₂H₅)₃Al catalyst was influenced by both the Al/Ti molar ratio and the addition of nickel acetylacetonate [Ni(acac)₂], and the maximum rate was observed at Al/Ti = 2.0 and Ni/Ti = 0.4 in molar ratios.     

Monomer-Isomerization polymerization. XXVIII. Catalytic activity of transition metals and alkylaluminums in monomer-isomerization polymerization of 2-butene

Monomer-isomerization polymerization of cis-2-butene (c2B) with Ziegler–Natta catalysts was studied to find a highly active catalyst. Among the transition metals [TiCl₃, TiCl₄, VCl₃, VOCl₃, and V (acac)₃] and alkylauminums used, TiCl₃? R₃Al (R = C₂H₅ and i-C₄H₉) was found to show a high-activity for monomer-isomerization polymerization of c2B. The polymer yield was low with TiCl₄? (C₂H₅)₃Al catalyst. However, when NiCl₂ was added to this catalyst, the polymer yield increased. With TiCl₃? (C₂H₅)₃Al catalyst, the effect of the Al/Ti molar ratio was observed and a maximum for the polymer yields was obtained at molar ratios of 2.0–3.0, but the isomerization increased as a function of Al/Ti molar ratio. The valence state of titanium on active sites for isomerization and polymerization is discussed.     

Monomer-isomerization polymerization. XXVI. Formation of polyallylcyclohexane from propenylcyclohexane through monomer-isomerization polymerization with Ziegler–Natta catalysts

Monomer-isomerization polymerization of propenycyclohexane (PCH) with TiCl₃ and R_3-xAICI_x (R = C₂H₅ or i-C₄H₉, x = 1–3) catalysts was studied. It was found that PCH underwent monomer-isomerization polymerization to give a high molecular weight polymer consisting of an allylcyclohexane (ACH) repeat unit. Among the alkyaluminum cocatalysts examined, (C₂H₅)₃Al was the most effective cocatalyst for the monomer-isomerization polymerization of PCH, and a maximum for the polymerization was observed at a molar ratio of Al/Ti of about 2.0. The addition of isomerization catalysts such as nickel acetylacetonate [Ni(acac)₂] to the TiCl₃–(C₂H₅)₃Al catalyst accelerated the monomer-isomerization polymerization of PCH and gave a maximum for the polymerization at a Ni/Ti molar ratio of 0.5. PCH also undergoes monomer-isomerization copolymerization with 2-butene (2B).     

Monomer-isomerization polymerization. XVI. Monomer-isomerization polymerization of methylpentenes with Ziegler-Natta catalyst

The polymerizations of 4-methyl-1-pentene(4M1P), 4-methyl-2-pentene (4M2P), 2-methyl-2-pentene (2M2P), and 2-methyl-1-pentene (2M1P) with Ziegler-Natta catalyst have been investigated. Both 4M1P and 4M2P were found to polymerize with TiCl₃–(C₂H₅)Al catalyst to give high molecular weight poly(4M1P), while 2M2P and 2M1P did not give polymers with 4M1P units. However, when the polymerizations of 2M1P and 2M2P were carried out with ternary catalyst systems, TiCl₃–(C₂H₅)AlCl–(PPh₃)₂PdCl₂ and TiCl₃–(C₂H₅)AlCl–Ni(SCN)₂ polymers with 4M1P units were obtained in low yield. It was concluded that these four methylpentenes could polymerize with the monomer-isomerization polymerization mechanism to poly(4M1P). The results of the observed isomer distribution of methylpentenes recovered, and the rate of polymerization of four methylpentenes suggest that the isomerization from 2M1P to 4M1P with the above ternary catalyst systems might proceed via a direct one-step isomerization mechanism.     

Monomer-isomerization polymerization. XXII.. Isomerization and polymerization of propenylbenzene with various ziegler–natta catalysts

The isomerization and polymerization of propenylbenzene (PB) with various Ziegler–Natta catalyst systems have been investigated. With the TiCl₃–(C₂H₅)₃Al (Al/Ti > 2.0) catalyst at 80°C, PB polymerized to give a polymer exclusively consisting of allylbenzene (AB) unit. During the polymerization, AB, which polymerized readily with the catalyst, was produced through isomerization of PB, indicating that PB underwent monomer-isomerization polymerization. PB also polymerized with isomerization to AB in the presence of TiCl₃?(C₂H₅)₂AlCl?NiCl₂ catalyst system, and a copolymer with PB and AB units was obtained. With TiCl₃?C₂H₅AlCl₂ catalyst, poly(PB) was formed via ordinary vinylene polymerization without isomerization. From these facts, it was concluded that the structure of the polymers produced from PB widely changed, depending on the catalyst systems used, which determine the rate of isomerization to AB and the polymerization reactivity of the PB and AB isomers formed.     

Hydrocarbon polymers containing six-membered rings in the main chain. Microstructure and properties of poly(1,3-cyclohexadiene)

The relationship between the microstructure and the properties of poly(1,3-cyclohexadiene)s, obtained by living anionic polymerization with an alkyllithium/amine system, and their hydrogenated derivatives are reported. The 1,2-bond/1,4-bond molar ratio of poly(1,3-cyclohexadiene) was determined by measuring 2D-NMR with the H H COSY method. The glass transition temperature of poly(1,3-cyclohexadiene) was found to rise with an increase in the ratio of 1,2-bonds to 1,4-bonds or with an increase of the number average molecular weight. The 1,2-bond of the polymer chain gives a high flexural strength and heat distortion temperature. Hydrogenated poly(1,3-cyclohexadiene) has the highest T_g (231°C) among all hydrocarbon polymers ever reported. 1,3-Cyclohexadiene–butadiene–1,3-cyclohexadiene triblock copolymer and 1,3-cyclohexadiene–styrene–1,3-cyclohexadiene triblock copolymer have high heat resistance and high mechanical strength. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1657–1668, 1998     

Monomer-isomerization polymerization. V. Effects of transition metal compounds on monomer-isomerization polymerizations of butene-2 and pentene-2

In order to clarify the correlation between polymerization and monomer isomerization in the monomer-isomerization polymerization of β-olefins, the effects of some transition metal compounds which have been known to catalyze olefin isomerizations on the polymerizations of butene-2 and pentene-2 with Al(C₂H₅)₃–TiCl₃ or Al(C₂H₅)₃–VCl₃ catalyst have been investigated. It was found that some transition metal compounds such as acetylacetonates of Fe(III), Co(II), and Cr(III) or nickel dimethylglyoxime remarkably accelerate these polymerizations with Al(C₂H₅)₃–TiCl₃ catalyst at 80°C. All the polymers from butene-2 were high molecular weight polybutene-1. With Al(C₂H₅)₃–VCl₃ catalyst, which polymerizes α-olefins but does not catalyze polymerization of β-olefins, no monomer-isomerization polymerizations of butene-2 and pentene-2 were observed. When Fe(III) acetylacetonate was added to this catalyst system, however, polymerization occurred. These results strongly indicate that two independent active centers for the olefin isomerization and the polymerizations of α-olefins were necessary for the monomer-isomerization polymerizations of β-olefins.     

Monomer-isomerization polymerization. VI. Isomerizations of butene-2 with TiCl3 or Al(C2H5)3–TiCl3 catalyst

A study of the isomerization of butene-2 with TiCl₃ or Al(C₂H₅)₃–TiCl₃ catalyst in n-heptane has been investigated at 60–80°C to elucidate further the mechanism of monomer-isomerization polymerization. It was found that positional and geometrical isomerizations in the presence of these catalysts occurred concurrently with activation energies of 14–16 kcal/mole. The presence of Al(C₂H₅)₃ with TiCl₃ catalyst could accelerate the initial rates of these isomerizations and initiate the monomer-isomerization polymerization of butene-2. From the results obtained, it was concluded that the isomerization of butene-2 proceeds via an intermediate σ-complex between the transition metal hydride and butene isomers.     

Influence of monomer structure on chemo- and stereoselectivity of 1,3-diene polymerization

MAO/CpTiCl₃ is an active catalyst for the polymerization of various types of 1,3-dienes. Butadiene, (E) - and (Z) −1,3-pentadiene, (E) −2-methyl-1,3-pentadiene and 2,3-dimethylbutadiene yield, at room temperature, polymers with a cis-1,4 or a mixed cis/1,2 structure. 4-Methyl-1,3-pentadiene and (E,E) −2,4-hexadiene give, respectively, a 1,2 syndiotactic and a trans-1,4/1,2 polymer. MAO/CpTiCl₂·2THF and MAO/(CpTiCl₂)_n are less active than the CpTiCl₃ catalyst, but give the same type of polymers. A change of stereospecificity with temperature was observed in the polymerization of (Z)-1,3-pentadiene: a cis-1,4 isotactic polymer was obtained at +20°C, and a crystalline 1,2 syndiotactic polymer at −20°C. This effect was attributed to a different mode of coordination of the monomer, which is cis-η⁴ at +20°C and may be trans-η² at −20°C. Results obtained with catalysts from CpTi(OBu)₃ and Ti(OBu)₄ are reported for comparison. An interpretation is given of the formation of cis-1,4 isotactic poly(2-methylpentadiene) and of 1,2 syndiotactic poly(4-methylpentadiene), as well as of syndiotactic polystyrene.     

Monomer-isomerization polymerization. XX. Monomer-isomerization polymerization of 2-, 3-, and 4-octenes with Ziegler–Natta catalyst

A study of the monomer isomerization polymerization of 2-, 3-, and 4-octenes has been made with TiCl₃–(C₂H₅)₃Al catalyst at 80°C in comparison with the ordinary polymerization of 1-octene. It was found that all these octenes underwent monomer-isomerization polymerization to give high-molecular-weight homopolymer consisting exclusively of the 1-octene unit. The addition of an isomerization catalyst such as nickel acetylacetonate accelerated this polymerization. The rates of polymerization were found to decrease in the following order: 1-octene > 2-octene > 3-octene > 4-octene. These results indicate that the isomerization proceeded by a stepwise double-bond migration. It was also found that the monomer-isomerization copolymerization of 2-octene and 2-butene occurred under similar conditions and produced copolymers of both 1-olefin units.     

Polymer-supported Ziegler–Natta catalyst for the polymerization of isoprene

A polymer-supported Ziegler–Natta catalyst, polystyrene-TiCl₄AlEt₂Cl (PS–TiCl₄AlEt₂Cl), was synthesized by reaction of polystyrene–TiCl₄ complex (PS–TiCl₄) with AlEt₂Cl. This catalyst showed the same, or lightly greater catalytic activity to the unsupported Ziegler–Natta catalyst for polymerization of isoprene. It also has much greater storability, and can be reused and regenerated. Its overall catalytic yield for isoprene polymerization is ca. 20 kg polyisoprene/gTi. The polymerization rate depends on catalyst titanium concentration, mole ratio of Al/Ti, monomer concentration, and temperature. The kinetic equation of this polymerization is: R_p = k[M]^0.30[Ti]^0.41[Al]^1.28, and the apparent activation energy ΔE_act = 14.5 kJ/Mol, and the frequency factor A_p = 33 L/(mol s). The mechanism of the isoprene polymerization catalyzed by the polymer-supported catalyst is also described. © 1993 John Wiley & Sons, Inc.     

Monomer-isomerization polymerization. XI. Monomer-isomerization copolymerizations of 2-butene with 2-pentene and 2-hexene with Ziegler-Natta catalyst

2-Pentene and 2-hexene were found to undergo monomer-isomerization copolymerizations with 2-butene by Al(C₂H₅)₃–VCl₃ and Al(C₂H₅)₃–TiCl₃ catalysts in the presence of nickel dimethylglyoxime or transition metal acetylacetonates to yield copolymers consisting of the respective 1-olefin units. For comparison, the copolymerizations of 1-pentene with 1-butene and 1-hexene with 1-butene by Al(C₂H₅)₃–VCl₃ catalyst were also attempted. The compositions of the copolymers obtained from these copolymerizations were determined by using the calibration curves between the compositions of the respective homopolymer mixtures and the values of D₇₆₆/D₁₃₈₀ in the infrared spectra. The monomer reactivity ratios for the monomer-isomerization copolymerizations of 2-butene (M₁) with 2-pentene and 2-hexene, in which the concentrations of both 1-olefins calculated from the observed isomer distribution were used as those in the monomer feed mixture, and for the ordinary copolymerizations of 1-butene (M₁) with 1-pentene and 1-hexene by Al(C₂H₅)₃-VCl₃ catalyst were determined as follows: 2-butene (M₁)/2-pentene (M₂): r₁ = 0.14, r₂ = 0.99; 1-butene (M₁)/1-pentene (M₂): r₁ = 0.30, r₂ = 0.74; 2-butene (M₁)/2-hexene (M₂): r₁ = 0.11, r₂ = 0.62; 1-butene (M₁)/1-hexene (M₂): r₁ = 0.13, r₂ = 0.90.     

Preparation and study of bi-supported Ziegler-Natta catalyst with nano graphene oxide and magnesium ethoxide supports for polymerization of polyethylene

In this study, we have reported the preparation of bi-supported Ziegler-Natta catalysts using magnesium ethoxide and graphene oxide as support. The polymerization process was carried out in slurry phase using triisobutylaluminum as a co-catalyst.The XRD analysis of TiCl₄/graphene oxide/Mg(OEt)₂ catalyst demonstrated that the space between the layers of graphene oxide had increased to 0.2 nm.The catalyst was characterized by XPS, BET, BJH, SEM, and TGA. The catalyst activity was studied for various Al/Ti molar ratios, and the catalyst activity was optimum at Al/Ti molar ratio of 315.     

Monomer-isomerization polymerization. XIX. Monomer-isomerization copolymerizations of methylbutenes and 2-butene with Ziegler-Natta catalyst

The copolymerization of 3-methyl-1-butene (3M1B), 2-methyl-2-butene (2M2B), or 2-methyl-1-butene (2M1B) with trans-2-butene (2B) was attempted in the presence of a Ziegler-Natta catalyst. It was found the 3M1B underwent monomer-isomerization copolymerization with 2B to give a copolymer consisting of both 3M1B and 1-butene (1B) units, with an infrared (IR) spectrum in good agreement with that obtained from the copolymerization of 3M1B with 1B under similar conditions. When the apparent copolymerization parameters obtained by a TiCl₃–(C₂H₅)₃Al catalyst were compared, the apparent reactivity of 3M1B observed in the 3M1B-2B system was much higher than that in the 3M1B-1B system. However, 2M2B and 2M1B did not undergo monomer-isomerization copolymerization with 2B, and only the homopolymer of 1B was obtained under similar conditions.     

Monomer-isomerization polymerization. XXXVIII. Monomer-isomerization copolymerizations of styrene and 2-Butene with Ziegler–Natta catalyst

Monomer-isomerization copolymerizations of styrene (St) and cis-2-butene (c2B) with TiCl₃-(C₂H₅)₃Al catalyst were studied. St and c2B were found to undergo a new type of monomer-isomerization copolymerization, i.e., only isomerization of 2B to 1-butene ( 1B ) took place to give a copolymer consisting of St and 1B units. The apparent copolymerization parameters were determined to be r_st = 16.0 and r_c2b = 0.003. The parameters were changed by the addition of NiCl₂ (r_St = 8.4, r_c2b = 0.05). The copolymers containing the major amount of St units were produced easily through monomer-isomerization copolymerization of St and 2B. © 1995 John Wiley & Sons, Inc.     

Monomer-isomerization polymerization. XXI.. Monomer-isomerization copolymerization of 3-methyl-1-butene and 2-pentene with ziegler–natta catalyst

3-Methyl-1-butene (3M1B) was found to undergo monomer-isomerization copolymerization with 2-pentene (2P) in the presence of Ziegler–Natta catalyst to give a copolymer exclusively consisting of 3M1B and 1-pentene (1P) units, the same as that obtained from copolymerization of 3M1B and 1P. The apparent copolymerization parameters were determined. The amount of 3M1B unit incorporated in the copolymers was found to increase in the copolymerization system of 3M1B-2P more than in that of 3M1B-1P. The polymers consisting of nearly complete 3M1B units were produced at a rapid rate through monomer-isomerization copolymerization of 3M1B with 2P in the presence of TiCl₃ ? (C₂H₅)₃Al catalyst.     

Monomer-lsomerization Polymerization of Some Branched Internal Olefins with a Ziegler-Natta Catalyst

New examples for the monomer-isomerization polymerizations of some branched internal olefins, 4-methyl-2-pentene and 4-phenyl-2-butene, are presented. When these olefins are polymerized with A1(C₂ H₅)₃-TiCl₃ ([TiCl₃] = 120 mmole/liter, A1/Ti = 3.0) catalyst at 80°C, considerable amounts of high polymers [27.5%/60 hr ([η] = 0.68 d1/g) and 35.6%/100hr, respectively] were obtained. From the additional fact that the isomerization from these 2-olefins to the mixture of their positional isomers including 1-olefins was observed during the polymerization, it is assumed that the polymerizations from these 2-olefins are performed with the 1-olefins which isomerized from the starting 2-olefins.     

The effect of the radical structure in trialkylaluminums on cis polymerization of dienes on titanium catalyst systems

1,4-cis-polymerizations of 1,3-dienes of TiCl₄-AIR₃ catalyst systems for isoprene and on TiI₂Cl₂-AIR₃ caltalyst systems for butadiene have been investigated. AIR₃ denotes herein an organoaluminum compound (OAC) containing hydrocarbon radicals, linear of different lengths or cyclic, both saturated and unsaturated, as well as those containing O, N, or Si atoms. Neither the OAC radical structure nor the Al/Ti ratios in the range investigated have been found to influence the stereospecificities and reactivities (chain propagation constant) of the active centers. Differing activities of the catalyst systems have been established to result from the variations in the concentrations of the active centers involving <1–5% of all the Ti species. The nature of the OAC radical does not change the mode of the molecular weight distribution in the polymers obtained. An increase in the molecular weight (MW) of the polydienes produced with the use of higher-MW trialkylaluminums was provoked by an increase in the macromolecules propagation period owing to the lower constant of chain transfer to the higher-MW OAC.     

Enhancement of stereospecificity in isoprene polymerization with alkylaluminum–titanium chloride catalysts through use of carbon disulfide

The effect of CS₂ on isoprene polymerization with triisobutylaluminum-titanium tetrachloride catalysts was studied at Al/Ti ratios of optimum (0.9) and higher values. In the absence of CS₂, appreciable amounts of low molecular weight oils (“extractables”) were formed at the expense of cis-1,4-polyisoprene with higher than optimum Al/Ti ratios. Small amounts of CS₂ were found to prevent extractables formation and allow attainment of higher yields of cis-1,4-polyisoprene. The optimum CS₂/Ti chloride molar ratio (0.1) was independent of the Al/Ti ratio of the catalyst. Polymer microstructure and dilute solution viscosity were unaffected by CS₂. The results support the theory that the catalyst surfaces hold two types of active sites: p-sites, which initiate polymerization, and o-sites, which lead to oligomerization. CS₂ appears to enhance polymerization by coordinating selectively at the o-sites. The predominance of oligomerization at the higher Al/Ti ratios was attributed to a destruction of p-sites by excess trialkyl-aluminum.