Poly alkylene Sulfide s

The reaction of suitable aliphatic dihalogen compounds with alkali or alkaline earth polysulfides results in the formation of linear, rubbery or resinous, poly(alkylene sulfide)s  

The most widely used dihalide is 1,2-dichloroethane. The use of polyhalides (e.g., 2% 1,2,3-trichloropropane) results in the formation of branched or crosslinked products. Sodium tetrasulfide (Na2S4) is generally used as the polysulfide since it contains scarcely any of the monosulfide which reacts with dihalides to form cycUc by-products with unpleasant odors. 

Sulfur can be removed from the poly(alkylene sulfide) with the aid of sulfurbinding agents for example, by treatment of an aqueous dispersion with Na2S, NaOH, or Na2S03 at 30-100°C, the sulfur content can be reduced to two atoms per 

Poly(alkene sulfide)s are prepared by allowing the dihalide to drip slowly under vigorous stirring into a moderately concentrated aqueous polysulfide solution (generally in 10-20% excess). Temperature and reaction time depend mainly on the dihalide being used for 1,2-dichloroethane, temperatures between 50°C and 80°C, and reaction times of about 5 h suffice on the other hand, long-chain dihalides 

Poly(alkene sulfide)s are prepared by allowing the dihalide to drip slowly under vigorous stirring into a moderately concentrated aqueous polysulfide solu- 

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Elastomersy based on poly(alkylene sulfide)s, are still another group of sulfur-containing polymers. They can be represented by a general structural formula of... 

Poly(alkylene sulfide)s are exceptionally oil-resistant elastomers. They also exhibit good resistance to solvents and to weathering. On the other hand, these elastomers lack the strength of synthetic rubbers and possess an unpleasant odor. 

Orientations in elongated mbbers are sometimes regular to the extent that there is local crystallization of individual chain segments (e.g., in natural rubber). X-ray diffraction patterns of such samples are very similar to those obtained from stretched fibers. The following synthetic polymers are of technical relevance as mbbers poly(acrylic ester)s, polybutadienes, polyisoprenes, polychloroprenes, butadiene/styrene copolymers, styrene/butadiene/styrene tri-block-copolymers (also hydrogenated), butadiene/acrylonitrile copolymers (also hydrogenated), ethylene/propylene co- and terpolymers (with non-conjugated dienes (e.g., ethylidene norbomene)), ethylene/vinyl acetate copolymers, ethyl-ene/methacrylic acid copolymers (ionomers), polyisobutylene (and copolymers with isoprene), chlorinated polyethylenes, chlorosulfonated polyethylenes, polyurethanes, silicones, poly(fluoro alkylene)s, poly(alkylene sulfide)s. 

Poly(ethylene oxide) is a linear polymer containing the donor oxygen atoms in the main backbone. Some other similar systems known to function as polymer electrolytes include simple poly ethylene glycol (PEG) [145], end acetylated PEG [146], poly propylene oxide (PPO) [ 147-148], poly(/ -propiolactone) [149], polyethylene succinate) [150-151],poly (ethylene adipate) [152],poly (ethylene imine) [153] and poly (alkylene sulfide) [154], Many of these form metal salt complexes. However, conductivities of the order of 10 s S cm are observed only at high temperatures. Table 5 summarizes this data. 

On this basis, it is not surprising that only a few kinds of reaction have so far been successfully applied in the synthesis of high-molecular linear polycondensates. High-molecular-weight polyesters (Section 26.4) or polyamides (Section 28.3) are obtained both by direct esterification or direct amidation of acids and by fr ns-esterification or Schotten-Baumann type reactions (see Section 17.4). The synthesis of polyurethane from diisocyanates and diols represents an addition of H to the N= double bonds (Section 28.5). Other addition reactions, such as HS—R—SH -h CH2=CH—R —CH=CH2 HS—R—S—CH2—CH2—R —CH=CH2, have not achieved any commercial significance. Poly(alkylene sulfides), on the other hand, are produced by nucleophilic substitutions (Section 27.1), while the polycondensation of benzyl chloride is an electrophilic substitution ... 

V. I. Klenin, M. Yu. Prozorova, L. S. Adrianova, Yu. V. Brestkin, G. P. Belonovskaya, and S. Ya. Frenkel, Study of the Structure of Mutually Penetrating Polymeric Systems Using Turbidity Spectrum and X-Ray Diffraction Methods, Vysokomol. Soedin. Ser. A. 19(5), 1138 (1977). IPNs of poly(tolylene diisocyanate. Poly(alkylene sulfide/polydiisocyanate IPNs. 

The structurally ordered poly(ester 0-sulfide)s are designated according to the number n of methylene units in the sulfide segment, or to the number m of methylene units in the fully alkylene segment in their repeat unit. 

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