Poly l-butenylene

Using 1,5-hexadiene, it was shown that, depending upon whether molybdenum- or ruthenium-based catalysts are employed, a change in mechanism appears to occur. In the presence of Schrock s molybdenum catalyst, 1,5-hexadiene produces principally linear poly(l-butenylene) [scheme (24)] [33], but with Grubbs s ruthenium catalyst the primary product is the cyclic dimer 1,5-cyclooctadiene [scheme (25)] [25,33] ... 

Styrene is frequently used as part of some terpolymers with large practical utilization. One such copolymer is acrylonitrile-butadiene-styrene terpolymer (ABS). Usually it is made as poly(l-butenylene-graft-l-phenylethylene-co-cyanoethylene). This form of the copolymer can be made by grafting styrene and acrylonitrile directly on to the polybutadiene latex in a batch or continuous emulsion polymerization process. Grafting is achieved by the free-radical copolymerization of styrene and acrylonitrile monomers in the presence of polybutadiene. The degree of grafting is a function of the 1,2-vinyl content of the polybutadiene, monomer concentration, extent of conversion, temperature and mercaptan concentration (used for crosslinking). The emulsion polymerization process involves two steps production of a rubber latex and subsequent polymerization of styrene and acrylonitrile in the presence of the rubber latex to produce an ABS latex. 

Fig. 16.1 Comparison of GC of macrocyclic species (C4H6) extracted from (a) the ROMP of COD and (b) the degradation of high-molecular-weight poly(l-butenylene) prepared from COD. Catalyst WCl6/EtMCl2/EtOH in both cases. X = di-/-butyl-p-cresol present as stabilizer. The two peaks at n = 3 are due to ctt and ttt isomers (Scott 1969).

Table 5.9.2 contains examples of common or semi-systematic names of comonomers. The systematic names of comonomers may also be used thus, die poly(acryloni1rile)-Z)/ocA -polybutadiene-Z)/ocA -polystyrene polymer may also be named poly(l-cyanoethylene)-Z)/ocA -poly(l-butenylene)-Z)/ocA -poly(l-phenylethylene). lUPAC does not require alphabetized names of comonomers within a polymer name many names are thus possible for same copolymers. 

Polychloro- prene Neoprene Chloroprene CR Poly(chloro- prene) Poly(l-chloro- 1-butenylene) BC,BE 125 30-95 22 600 233... 

Figure 5.1 Stereoisomerism of cis-, A polymers of 1,4-disubstituted butadienes, poly(3,4-dialkyl-cw-l-butenylene) CH=CH CH(R) CH(R) n- or [-CH(R>-CH=CH—CH(R)—] —. Diisotactic and disyndiotactic erythro and threo polymers only one of the enantiomorphic forms of the polymers is shown...

In the spectmm of poly( 1-butenylene), the a-carbons are sensitive to the configuration of the nearest double bond, but almost insensitive to that of the next nearest double bond, even though it is only three bonds away two opposing effects must cancel in this case. The olefinic carbons on the other hand are sensitive to the configuration of the next nearest double bond, which is four bonds away. When the polymer is made from cw,c/s-cycloocta-l,5-diene, every other double bond in the chain is preformed and must be cis. The spectrum of freshly formed polymer therefore shows only tc, cc, and ct olefinic peaks at 130.15, 129.63, and 129.46... 

ALTERNATIVE NAMES. ACRONYMS, TRADE NAMES Poly(l-chloro-l-butenylene), poly(2-chloro-1.3-butadiene), chloroprene rubber (CR), GR-M, Baypren, Butaclor , Neoprene, Perbunan C, Skyprene... 

MAJOR APPLICATIONS Low molecular weight atactic polypropylene is used as a component of hot melt adhesives and sealants. Atactic" polypropylene which is produced as a by-product of isotactic PP production is not ideally atactic or completely amorphous. Ideally atactic polypropylene has been prepared by hydrogenation of poly(2-methyl-l,3-pentadiene), that is, poly(l,3-dimethyl-l-butenylene) or PDMB/ Recently, directly synthesized atactic pwlypropylene and other amorphous poly(a-olephins) (APAO or APO) have been developed. 

The second example of a polymer reaction is the industrial cross-linking of rubber by vulcanization sketched in Fig. 3.50. The process was invented already in 1839 by C. N. Goodyear without knowledge of its chemical stracture. Natural rubber is cis-poly(l-methyl-1-butenylene) or polyisoprene with a low glass transition temperature of about 210 K. Its structure and those of other rubbers are given in Fig. 1.15. The addition of sulfur in the form of Sg rings and heating causes the vulcanization. Of the listed cross-hnks in Fig. 3.50, only the left example is an efficient network former. The sulfur introduces about 1 cross-link for each of 50 S-atoms used. Modem vulcanization involves activators and accelerators for increased efficiency. The detailed mechanism is rather complicated and not fully understood. 

A typical entropy-elastic material is cross-linked natural rubber, ds-poly(l-methyl-1-butenylene) or cts-l,4-polyisoprene, as summarized in Fig. 5.166 (see also Fig. 1.15). Its extensibility is 500 to 1,000%, in contrast to the 1% of typical energy-elastic sohds. Natural rubber has a molar mass of perhaps 350,000 Da (about 5,000 isoprene monomers or 20,000 carbon backbone bonds) and is then vulcanized to have about 1% cross-links (see Fig. 3.50). A rubber with a Young s modulus of 10 Pa (depending on cross-link density) must be compared to its bulk modulus (= 1/p,... 

An alternative approach to preparing i-PP standard reference materials has been suggested by Fetters etal [37], using narrow-distribution atactic polypropylenes, a-PP. The anionic polymerization of 2-methyl-1, 3-pen-tadiene with s c-butyl lithium occurs exclusively by 1,4-addition to produce poly(l,3-dimethyl-l-butenylene). The polymers are monodisperse in molecular mass distribution. Hydrogenation transforms them into a-PP. Light scattering and osmometry were carried out, as well as viscosity measufements in tetrahydrofuran and 2-octanol, a 0-solvent, and the intrinsic viscosity were related to the mass average molecular mass ... 

C/5-1,4-polyiso-prene Rubber Poly(l -methyl-c/s-1 -butenylene) 9003- 31-0 -75 1.53... 

Poly(alkenylene) Polyalkadiene -[CH=CHCH2CH ]-Poly(cis-l-butenylene)... 

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