Trans14polyisoprene

Trans-1,4-polyisoprene, commonly referred to as trans-14-polyisoprene, is a polymer of isoprene in which the repeating units connect through trans-1,4 linkages. This stereochemistry contrasts with the more familiar cis-1,4-polyisoprene that constitutes natural rubber. The trans form tends to be more crystalline and rigid, resulting in different physical properties such as higher density and modulus and lower elasticity compared with the cis form.

Natural occurrence and historical context: The best-known natural trans-1,4-polyisoprene is gutta-percha, obtained from the sapodilla family of trees (notably Palaquium gutta). Gutta-percha forms solid, relatively dense materials that soften upon heating and have been used historically for various applications, including dental and electrical uses. In the 19th and early 20th centuries, gutta-percha played a key role in cable insulation before synthetic polymers became dominant, and it remains used in some dental applications today.

Synthesis and processing: Trans-1,4-polyisoprene can be produced by polymerizing isoprene under conditions and catalysts that favor trans-1,4 addition, yielding a more crystalline polymer. Naturally, gutta-percha is formed in this trans configuration. Synthetic routes typically aim to control stereochemistry to achieve the desired balance of rigidity and thermal properties. The material is generally more sensitive to oxidation than cis-polyisoprene and is often stabilized with antioxidants or blended with other polymers for improved performance.

Applications and properties: Due to its crystallinity and rigidity, trans-1,4-polyisoprene finds use in specialty applications such as dental obturation materials and legacy cable insulation, as well as in certain molded or blended polymer systems. It is less elastic than cis-1,4-polyisoprene and tends to exhibit poorer resilience, making it suitable for applications where rigidity and dimensional stability are desired.

See also: cis-1,4-polyisoprene.