Butadiene Ziegler—Natta copolymerization

Only a few papers describe the polymerization of unsaturated monomers with a covalent M-O bond. Ziegler-Natta copolymerization of the diisobutylaluminium-alkoxy-isopren derivative 35 with butadiene occurs by a neodynium catalyst in a hydrocarbon solvent [180]. Mainly the monomer 35 in, A-cis configuration is found in the copolymer. A chiral monomer based on ethyleneglycolmonomethacrylat being substituted by alkoxy derivatives of Ti(IV) and different chiralic substituents was polymerized [181]. Such polymers are interesting as chiralic catalysts. 

Catalysts of the Ziegler-Natta type are applied widely to the anionic polymerization of olefins and dienes. Polar monomers deactivate the system and cannot be copolymerized with olefins. J. L. Jezl and coworkers discovered that the living chains from an anionic polymerization can be converted to free radicals by the reaction with organic peroxides and thus permit the formation of block copolymers with polar vinyl monomers. In this novel technique of combined anionic-free radical polymerization, they are able to produce block copolymers of most olefins, such as alkylene, propylene, styrene, or butadiene with polar vinyl monomers, such as acrylonitrile or vinyl pyridine. 

R = CH3, CH2SiMe3),96 VO(CH2SiMe3)3, [(Me3CCH2)3V]2(/J,-N2),97 and [V(mes)3(THF)] are all isolable. The latter is a convenient starting material because it is easily prepared and reacts readily with protic sources such as a-amino acids.98 Unstable alkyls are present in the solutions of vanadium oxides or halides and A1 alkyls,99 which are used in the Ziegler-Natta type reaction for the copolymerization of styrene, butadiene, and dicyclopentadiene to give synthetic rubbers. 

An important extension of Ziegler-Natta polymerization is the copolymerization of styrene, butadiene and a third component such as dicyclopentadiene or 1, 4-hexadiene to give synthetic rubbers. Vanadyl halides rather than titanium halides are then used as the metal catalyst. 

Most unsaturated substances such as alkenes, alkynes, aldehydes, acrylonitrile, epoxides, isocyanates, etc., can be converted into polymeric materials of some sort—either very high polymers, or low-molecular-weight polymers, or oligomers such as linear or cyclic dimers, trimers, etc. In addition, copolymerization of several components, e.g., styrene-butadiene-dicyclo-pentadiene, is very important in the synthesis of rubbers. Not all such polymerizations, of course, require transition-metal catalysts and we consider here only a few examples that do. The most important is Ziegler-Natta polymerization of ethylene and propene. 

The 1,2-disubstituted olefmic monomers will usually not homopolymerize with the Ziegler-Natta catalysts. They can, however, be copolymerized with ethylene and some a-olefins. Due to poorer reactivity, the monomer feed must consist of higher ratios of the 1,2-disubstituted olefins than of the other comonomers. Copolymers of cw-2-butene with ethylene, where portions of the macromolecules are crystalline, form with vanadium-based catalysts. The products have alternating structures, with the pendant methyl groups in erythrodiisotactic arrangements. Similarly, vanadium-based catalysts yield alternating copolymers of ethylene and butadiene, where the butadiene placement is predominantly rm/w-1,4. ... 

Another example of ionic graft copolymerization is a reaction carried out on pendant olefinic groups using Ziegler-Natta catalysts in a coordinated anionic-type polymerization. The procedure consists of two steps. In the first, diethylaluminum hydride is added across the double bonds. In the second the product is treated with a transition metal halide. This yields an active catalyst for polymerizations of a-olefms. By this method polyethylene and polypropylene can be grafted to butadiene styrene copolymers. Propylene monomer polymerization results in formations of isotactic polymeric branches ... 

The pre-eminent interest in lanthanides for the polymerization and copolymerization of conjugated diolefins is demonstrated by a large scientific and patent literature. A recent paper by one of us (24) reviewed the main worldwide contributions on butadiene and isoprene polymerization. Very recent contributions in this field come from Hsieh and Yeh (25). They observed that the butadiene polymerization in n-pentane evolves as a slurry process, the cis-polybutadiene being insoluble in the light hydrocarbon. They also measured a lower activation energy for Nd-based than for conventional Ziegler-Natta catalysts foi- both butadiene and isoprene polymerization. 

The copolymerizations between monoolefins and dienes have been considered to be of practical and theoretical importance. As reported in the literatures ethylene-butadiene and propylene-butadiene copolymers can be prepared with conventional Ziegler-Natta titanium-based or vanadium-based catalysts. The copolymer composition and monomer sequence distribution strongly depend on the catalyst system and polymerization conditions. Alternating copolymers were synthesized when the catalyst components were mixed at the... 

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