Trans-polybutadienes

Another example of such a behavior is provided by the interesting polymerization of butadiene molecules imprisoned in tubes of clathrates of urea.9 Of course, the configuration of the resulting polymer is strongly influenced by the order introduced in the assembly of monomers and thus all trans polybutadiene is formed. 

Differently from the cases of ETFE, PTFE, 1,4-trans-polybutadiene, and PE, in the mesomorphic form of i-PP it is believed that there is a nearly complete conformational order, in the chains packed with parallel axes, (intrachain long range 3-D order) and only short-range lateral order in the positioning of the chain axes [60, 61]. 

The main conclusions of the strain induced crystallization behavior of high trans polybutadiene based rubber and natural rubber are (1) the rate of crystallization is extremely rapid compared to that of NR (2) the amount of strain induced crystallization is small compared to that of NR, especially at room temperature and (3) for the high trans SBR s relative to NR, crystallization is more sensitive to temperature at low extension ratios, and crystallization is less sensitive to strain. 

It has been known that 7r-allylnickel halides are catalysts for polymerization of butadiene (50, 51). When the halide is chloride, the polymer formed is cis-polybutadiene when the halide is iodide, the polymer is trans-polybutadiene. Porri and co-workers (50) interpret this effect in terms of the ease of dissociation of the dimeric complex 29 by butadiene. The chloride complex... 

Phys. Condens. Matter, 9, 3803 (1997). A Light-Scattering Study of 1,4-cis-trans Polybutadiene. 

The properties of impact polystyrene can be improved by simultaneous grafting and crosslinking upon rubber. Changing cis-polybutadiene into trans-polybutadiene and eliminating the 1,2-vinyl configuration through radiation are discussed by Parkinson. 

The strongly anionic alkali metal naphthalene compounds produced very large amounts of 1.2 (or 3.4) structure. The remainder of the polymer was 1.4-trans. No 1.4-cis polymer was produced. Increasing anionic catalysts such as rubidium and cesium produce even larger amounts of 1.4-trans-polybutadiene. 

Mit dem Katalysatorsystem DialkylalummiumcMoridjKobaltsalzj Vanadinsalz kann man Gemische von 1.4-cis- und 1.4-trans-Polybutadien herstellen, die bis jetzt noch keinen technischen Einsatz gefunden haben 89b... 

Other amines reduced the molecular weight of the polymer (Table V) but only with triethylamine and trimethylamine was high trans polybutadiene formed. 

Figure 8. Catalyst concentration and yield of trans-polybutadiene Al/Co/NEh = 10/1/8.5...

Figure 9. Effect of temperature on yield of trans-polybutadiene Al/Co/NEts = 10/1/9.5 CoCh = 2.5 grams/liter...

Metal—Carbon Bonds in Cobalt-Catalyzed Polymerization. Concentrations of metal-carbon bonds were determined (using tritium labelled alcohol) with increase in conversions. Experiments were made in two solvents (petrol and benzene) with two cobalt salts (chloride and naphthenate) under conditions giving rise either to liquid mixed structure or to high trans polybutadiene. The data are summarized in Table XI. Table XII and Figure 11 shows optical properties of some cobalt salts and complexes. 

The newest results obtained by Rabek and Rfinby (67) show that during dye sensitized singlet oxygen photo-oxidation of cis- and trans-polybutadiene rapid degradation ocour what has been indicated by viscosity (Fig.4) and Gel Permeation Chromatography (GPC)(Pig.5). 

Figure 5. Gel-permeation chromatograms of (A) cis- and (B) trans-polybutadiene-1,4- (—) undegraded polymer and degraded in the presence of FL-fluoresceine, MB-methylene blue, and RB-Rose Bengal. Concentration of dyes in benzene-methanol (9 1) solution of polyoutadienes was 10- M/1.

Soectrosconie Studies. The photoproducts were characterized by spectroscopic methods. In Figure 2 the infrared spectra of 1 as monomer and after exposure to various y-ray doses are shown. With increasing radiation dose the intensities of the C C-stretching (1635 and 1620 cm ) and wagging (1f)00 cm ) modes decrease. Simultaneously a new mode appears at 960 cm, which can be ascribed to an isolated trans-C C-unit as it typically occurs in 1,4-trans-polybutadienes. 

We have examined the microstructure of a number of dichlorocarbene adducts of both cis- and trans-polybutadiene using 13C NMR spectroscopy. Samples were prepared in a two phase system where dichlorocarbene was generated by the reaction of either concentrated aqueous or solid alkali metal hydroxide with chloroform in the presence of a phase transfer catalyst (14t). Monomer compositions and sequence lengths were obtained as for true copolymers and were correlated with glass transition temperature and phase morphology. 

In Table I are some pertinent data for a number of dichlorocarbene adducts of cis- and trans-polybutadiene. Figure 1 shows the 13C NMR spectra of three cis-polybutadiene-based adducts having widely different chlorine contents. At low percent Cl, i.e. low extent of reaction, the spectrum is essentially that of cis-polybutadiene (15) with some additional smaller resonances due to the presence of modified butadiene units (Figure 1A). With increasing chlorine content, these additional resonances grow relative to those due to... 

Table I. Glass Transition Temperatures, Compositions, and Reaction Conditions of Some Dichlorocarbene Adducts of Cis- and Trans- Polybutadiene...

We can visualise the capability of suitable lanthanide (Ln) compounds (J, 6), e.g. as homogeneous catalysts with respect to olefins, by invoking similar intermediates. Although the series of reportedly catalytically active Ln-complexes spans from the pure trihalide via tris(B-diketonato)complexes to the organo-metallic tris(cyclopentadienyl) and tetra(allyl)complexes (8), respectively, no really optimal combination of ligands on a Ln-element has been found so far. Promising aspects are, however, based on some evidence for "reaction steering" in that either cis- or trans-polybutadienes can be obtained from 1,3-dienes, and either polymers or metathesis products from monoolefins, respectively (Table I). 

Rhodium trichloride has been used to catalyze a number of organic reactions. Thus in aqueous emulsions it induces the stereoregular polymerization of butadiene to trans-polybutadiene and it catalyzes the isomerization of various alkenes in ethanolic solutions. 

Styrene - Crystalline Polystyrene 85% Styrene - Styrene Butadiene Copolymer 45% Styrene Styrene Butadiene Copolymer 30% Styrene Styrene Butadiene Copolymer 23% Styrene - Styrene Butadiene Copolymer 5% Styrene - Styrene Butadiene Copolymer Cis Polybutadiene Cis-Trans Polybutadiene... 

Fig. 3 Mass scan for cis, trans Polybutadiene between the limits of 15 and 200 amu.

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