Coordination chain polymerization: using Ziegler-Natta catalyst TiCl4/Al(i-C4H9)3 to form more pure cis-1,4-polyisoprene similar to natural rubber. Formation of trans polyisoprene using Ziegler–Natta catalyst VCl3/Al(i-C4H9)3. [4]
1,2 and 3,4-dominated polyisoprenes were produced from MoO2Cl2 catalysts supported by phosphorus ligands and Al(OPhCH3)(i-Bu)2 cocatalysts.
Natural rubber and synthetic polyisoprene are mainly used in tires. Other applications include latex products, footwear, belts, hose and condoms. [7]
Natural teethers and synthetic trans-1,4-polyisoprene are used in golf balls.
Cis-polyisoprene is derived from rubber trees. A general purpose natural rubber ranging from soft rubber (eraser) to hard rubber. Usually amorphous in the unstrained state, not to be confused with gutta-percha (or hevea), the rigid partially crystalline natural polymer of trans-polyisoprene. General properties include excellent mechanical properties with high tear and abrasion resistance; high elasticity at 200 °C and therefore little heat generation under the action of mechanical vibrations.
Natural rubber contains 97 wt% cis-1,4-polyisoprene and about 3 wt% protein. The protein moiety can be considered as a natural compatibilizer between polyisoprene and other hydrophobic compounds such as starch. Natural rubber was one of the first commercially available polymers, and its structure and properties, processing and recycling have been extensively studied.
Each chain unit of both polyisoprenes has a double bond from the first two putative monomers. They remain reactive like other molecules containing non-conjugated organic double bonds. It has been found5 that heating natural rubber with sulfur at about 200 °C produces a product that is more elastic and does not become sticky when heated.
