Elastomer synthesis dienes

The growing importance of thermoplastic elastomers is clearly evident from the papers presented at this Symposium. The majority of papers on elastomer synthesis deal with these types of block copolymers. The papers by Quirk and Tung describe the triblock copolymers based on -methylstyrene-butadiene and styrene-a-methylstyrene-diene systems, respectively. Anionic block copolymerization of hexamethyl- and hexaphenylcyclotrisiloxane is discussed in the paper (not included in this book) by Ibemesi, Gvozdic, Keumin, Lynch and Meier,... 

ADMET is quite possibly the most flexible transition-metal-catalyzed polymerization route known to date. With the introduction of new, functionality-tolerant robust catalysts, the primary limitation of this chemistry involves the synthesis and cost of the diene monomer that is used. ADMET gives the chemist a powerful tool for the synthesis of polymers not easily accessible via other means, and in this chapter, we designate the key elements of ADMET. We detail the synthetic techniques required to perform this reaction and discuss the wide range of properties observed from the variety of polymers that can be synthesized. For example, branched and functionalized polymers produced by this route provide excellent models (after quantitative hydrogenation) for the study of many large-volume commercial copolymers, and the synthesis of reactive carbosilane polymers provides a flexible route to solvent-resistant elastomers with variable properties. Telechelic oligomers can also be made which offer an excellent means for polymer modification or incorporation into block copolymers. All of these examples illustrate the versatility of ADMET. 

Synthesis and Properties of Diene Elastomers With Controlled Structure... 

Gheneim R, Perez-Beramen C, Gandini A. Diels-Alder reactions with novel polymeric dienes and dienophiles synthesis of reversibly cross-linked elastomers. Macromolecules 2002 35 7246-7253. 

Kennedy, J. P. and Chou, T. Poly(isobutylcnc-co-(J-Pinenc) A New Sulfur Vulcanizable, Ozone Resistant Elastomer by Cationic Isomerization Copolymerization. Vol. 21, pp. 1-39. Kennedy, J. P. and Delvaux, J. M. Synthesis, Characterization and Morphology of Poly(buta-diene-g-Styrene). Vol. 38, pp. 141-163. 

A comonomer for the synthesis of ethylene/propene elastomers - 2-ethylidene-norbomene (7) - is synthesised via a Diels-Alder cycloaddition of cyclopenta-diene and butadiene followed by an isomerization with titanium-based catalysts of the intermediate 2-vinyl derivative 6 in excellent yield (98 %) (eq. (12)) [22]. 

In a similar way, our team has done lots of work in functionalizing a,a>-diiodoperlluoroalkanes into fluorotelechelic compounds. These works were summarized by Ameduri et al. [244] in a review on the synthesis of fluo-ropolymers. For instance, our team synthesized a,co diols or dienes of perflu-oroalkanes [245-248]. These compounds are precursors of hybrid fluorosil-icones [249] but also of thermoplastic elastomers by polycondensation with polyimide sequences [250]. 

More recently, we have also reported the synthesis of thermoplastic siloxane elastomers based on hybrid polysiloxane/polyimide block copolymers (the hybrid polysiloxane being fluorinated or not) that were obtained through polyhydrosilylation of dienes with a,dihydrooligosiloxanes [76-78], as follows ... 

Uses Catalyst in mfg. of rubbers and plastics based on styrol-butadiene, polyisoprene, and polybutadiene initiator in anionic polymerization of styrene and conjugated dienes, thermoplastic elastomers organic synthesis... 

BIMS-NR blends as sidewall components. In many of the applications, the saturated elastomer is considered a polymeric antioxidant for the diene rubber. It is believed that the higher molecular weight polyolefins are better in these applications due to limited interdiffusion and a more stable morphology. Some of the benefits in tensile properties and abrasion resistance of the blends may be due to the interdiffusion of high molecular chains of dissimilar elastomers across the phase interface. Significant advances have been made in modifying the structure of polyolefin elastomers to increase the compatibility to unsaturated elastomers. Tse et al. [50b] have shown that uncompatibilized blends of saturated elastomers and unsaturated elastomers are possible if the former contains substantial amounts (>12%) styrene residues. This is expected to be an important area of development in the future with the advent of new synthesis procedures for polyolefins. 

I. G. Hargis, R. A. Livigni, and S. L. Aggarwal, in J. Mark and co-workers, eds., ACS Symposium Series 193 Synthesis and Properties of Diene Elastomers with Controlled Structure, American Chemical Society, Washington, D.C., 1982, p. 73. 

These elastomers contain unsaturation in the main chain. The letter immediately before the "R" designates the conjugated diene which is used in its synthesis (except natural rubber.)... 

The general reaction chemistry used in the synthesis of common rubbers and elastomers mentioned in Table 21.1 is described in the following. The discussion covers four types of rubbers styrene-butadiene rubbers (SBRs), polybutadiene, ethylene-propylene-diene rubbers, and thermoplastic polyurethanes. 

Hargis, I. G. Livigni, R. A. Aggarwal, S. L. In Synthesis and Properties ol Diene Elastomers with Controlled Stmcturn Mark, J., Lai, J., Eds. ACS Symposium Series 193 American Chemical Sociely Washinglon, DC, 1982 p 73. 

Since the earliest successful synthesis of block copolymers in seminal investigation of living anionic polymerization by Szwarc [ 1,2], diene-based block copolymers, such as polystyrene- tocA -polybutadiene (SB diblock), polystyrene-fetocA -polyisoprene (SI diblock), polystyrene-fetocfc-polybutadiene-( tocfc-polystyrene (SBS triblock), and polystyrene- /oc -polyisoprene-I tocA -polystyrene (SIS triblock) copolymers have been widely used in the thermoplastic elastomer industry due to their unique physical properties not attainable with the constituent homopolymers alone. 

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