Butadiene-propylene copolymer alternating

Very active catalysts for the preparation of strictly alternating butadiene-propylene copolymers (BPR) consist of V0(0R)2C1/i-Bu Al (R = neopentyl). The CH3 side groups in BPR stiffen the polymer chain and were expected to promote the formation of strain-induced structures. The fact that we could not detect strain-induced crystallization is probably due to an atactic configuration of the propylene units. 

The predominance of alternating structures was established by ozonolysis and by NMR techniques. In the case of the butadiene-propylene copolymers the butadiene units appear to be predominantly of the trorts-1,4 type. 

This technique has been applied to a study of sequencing in butadiene-propylene copolymer [80-82]. Samples of highly alternating copolymers of butadiene and propylene yielded large amounts of 3-methyl 1,6 hexane dial when submitted to ozonolysis. The ozonolysis product from 4-methyl cyclohexane-1 was used as a model compound for this structure. Ozonolysis of these polymers occurs as shown next ... 

Table 5.14 shows results obtained for several butadiene-propylene copolymers having more or less alternating structure. 

The amount of alternation in these polymers can he determined if the amounts of 1,4 and 1,2 polyhutadiene structure and total propylene have been determined by infrared or NMR spectroscopy. Table 9.8 shows results obtained for several butadiene-propylene copolymers having more or less alternating structure. Similar polymers have been analysed by Kawasaki [159] by use of conventional ozonolysis methods with esters as the final products. 

The addition of free radical initiators can produce different effects in the polymerization of CT complexes. Dibenzoyl peroxide increases the molar mass of the alternating copolymer from butadiene/propylene/VCL/EtsAl since hydrogen transfer is reduced. But addition of dibenzoyl peroxide to... 

Hydrogenated random copolymers of 1.4- and 1.2-butadiene represent another class of crystalline-amorphous materials [10-15,17). Following hydrogenation, the resultant copolyolefin contains ethylene (E) and 1-butene (B) units. These materials can be described as PEB-n where n denotes the mun-ber of ethyl units per 100 backbone carbons. Eor samples where n < 12 the samples will show partial crystallinity at room temperature while for n > 13 the samples are amorphous in the bulk state. The latter PEB copolymers lack self-assembly capacity. An equivalent amorphous segment is derived from polyisoprene. In this case hydrogenation yields the essentially alternating ethylene-propylene copolymer (PEP). This material also contains about 7% isopropyl units that randomly appear between the ethylene-propylene units. 

Figure 4. Pulsed FT C-13 NMR spectrum of the polyalkane obtained by hydrogenating an alternating propylene butadiene copolymer made with a titanium catalyst, Copolymer B. The spectrum was obtained at ambient temperature from...

Other commercial copolymers which are typically random are those of vinyl chloride and vinyl acetate (Vinylite), isobutylene and isoprene (butyl rubber), styrene and butadiene (SBR), and acrylonitrile and butadiene (NBR). The accepted nomenclature is illustrated by EP, which is designated poly-ethylene-co-propylene the co designating that the polymer is a copolymer. When the copolymers are arranged in a regular sequence in the chains, i.e., ABAB, the copolymer is called an alternating copolymer. A copolymer consisting of styrene and maleic anhydride (SMA) is a typical alternating copolymer. 

Alternating copolymers of butadiene and propylene exhibit good elastomeric properties [213,221]. 

In a practical sense the hydrocarbon monomers that work best in anionic systems are styrene, a-methylstyrene, p-(tert-butyl)styrene, butadiene, isoprene, 2,3-dimethyIbutadiene, piperylene, stilbene, and 1,1-diphenylethylene. The latter two monomers give rise to alternating copolymers with other dienes but do not homopolymerize. Among the polar monomers (C) that can be polymerized are such monomers as 2-vinyIpyridine, pivalolactone, methacrylonitrile, methyl-methacrylate, ethylene oxide (not with Li-counterion), ethylene sulfide, and propylene sulfide. However, polymerization of many of these polar monomers suffers from side reactions and complicating termination or transfer reactions not present in the... 

In fact, it has been established [89] in the investigation of factors determining the structure of alternating copolymers of butadiene and propylene by the TiCl4-C6H5COCH3 Al(i-Bu)3 catalyst system that an alternating copolymer is formed on paramagnetic binuclear complexes erf dialkylated derivatives of Ti+3. 

Marvel reported that propylene and cyclohexene react with sulfiir dioxide to form alternating copolymers of olefin and sulfiir dioxide in a head-to-tail arrangement [2,4], Staudinger reported that 1,3-butadiene reacts with sulfur dioxide to form a cyclic sulfone and an amorphouse linear polysulfone [3,3a, 5]. 

Although presently lacking industrial importance, alternating copolymers can be made from propylene and butadiene, also from propylene and isoprene. Copolymers of propylene and butadiene form with vanadium- or titanium-based catalysts combined with aluminum. alkyls. The catalysts have to be prepared at very low temperature (-70 C). Also, it was found that a presence of halogen atoms in the catalyst is essential.Carbonyl compounds, such as ketones, esters, and others, are very effective additives. A reaction mechanism based on alternating coordination of propylene and butadiene with the transition metal was proposed by Furukawa. ... 

Apart from the major reviews, numerous publications have appeared in the last two years which report new monomer combinations for alternating copolymerization or which seek to throw light on the numerous problems which still exist in this burgeoning field of study. Many comonomer systems have been reported in the last two years which give rise to alternating copolymers by one or more of the mechanisms which have been outlined, including acrylonitrile with acenaphthalene, cyclopenta-1,3-diene p-aminostyrene with p-nitro-styrene and other vinyl monomers butadiene with 1,2-dicarbomethoxy ethylenes, acrylonitrile, propylene, and others isoprene with mono-... 

It has been shown that the hydrogenation of 1,4-polybutadiene (PB) can lead to a thermoplastic material with a structure identical to a linear polyethylene. Perfect alternating copolymers of ethylene with propylene can be achieved by hydrogenating 1,4-polyisoprene (PI). Head-to-head tail-to-tail polypropylene can be obtained by hydrogenating l,4-poly(2,3-dimethyl butadiene)(PDMB), 1,4-poly(2,4-hexadiene) PHXD) or head-to-tail l,4-poly(3-methyl-l,3-pentadiene). 

Modifications to the Ziegler-Natta catalyst system have led to the preparation of alternating copolymers from olefins, such as ethylene and propylene, and diolefins, such as butadiene and isoprene. In typical systems (Furukawa 1972, 1974a, b) the catalyst is prepared at very low temperatures (-70°C or below) from three components a... 

This is found in amorphous ethylene-propylene alternating copolymers, polybutene-2-ethylene alternating copolymer, and hydrogenated poly 2,3-dimethyl butadiene ... 

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... 

This is equivalent to the alternating copolymer of butadiene, ethylene, and propylene [7]. 

Furukawa and coworkers [81-83] have developed procedures for preparing alternating copolymers of butadiene with propylene and other 1-olefins. The structures of these polymers have been studied by 220 MHz pmr [84] and 25 MHz cmr spectroscopy [85]. 

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