Hydrohalogenated 1,4-polyisoprenes

Figure 3. A 220-MHz NMR spectra of the hydrohalogenated 1,4-polyisoprene samples. Chlorobenzene solutions at 100°C with TMS as reference.

CHEMICAL MODIFICATION The following chemical modifications of cis-1,4-polyisoprene are employed as a convenient way of altering physical and mechanical properties hydrohalogenation, halogenation, oxidation, ozonolysis, hydrogenation, carbene addition, cyclization. ... 

Since 1,4-polyisoprene has a secondary carbon atom at the double bond it follows that it is generally more reactive to both free radicals and to carbonium ions than 1,4-poly butadiene. The typical addition reactions associated with the double bond suggest that the ultimate hydrogenated, halogenated, hydrohalogenated and isomerized diene polymers would have the same structure irrespective of the initial cis-ltrans- ratio. 

Representative diene-based polymers include natural rubber (NR), polyisoprene (PIP), PBD, styrene—butadiene rubber (SBR), and acrylonitrile-butadiene rubber (NBR), which together compose a key class of polymers widely used in the rubber industry. These unsaturated polyolefins are ideal polymers for chemical modifications owing to the availability of parent materials with a diverse range of molecular weights and suitable catalytic transformations of the double bonds in the polymer chain. The chemical modifications of diene-based polymers can be catalytic or noncatalytic. The C=C bonds of diene-based polymers can be transformed to saturated C—C and C—H bonds (hydrogenation), carbonyls (hydrofbrmylation and hydrocarboxylation), epoxides (epoxidation), C—Si bonds (hydrosilylation), C—Ar bonds (hydroarylation), C—B bonds (hydroboration), and C—halogen bonds (hydrohalogenation). ... 

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