Recent Advances in Functional Polyisoprene: From Precision Synthesis to Smart Elastomers

Polyisoprene is an important elastomer with a tunable microstructure and a hydrocarbon backbone analogous to the rubber component of natural rubber. However, conventional synthetic polyisoprene lacks the complex intermolecular interactions associated with non-rubber components in natural rubber, limiting its mechanical performance and functional versatility. Recent advances in precision polymerization and functionalization provide new opportunities for developing high-performance and adaptive polyisoprene elastomers. This review summarizes progress in polyisoprene precision synthesis, microstructure control, and functionalization, with emphasis on the relationships among molecular structure, chemical reactivity, network architecture, and macroscopic properties. Coordination and living/controlled polymerization enable regulation of stereoregularity, molecular weight, and chain-end functionality, while epoxidation, hydroxyl functionalization, halogenation, click chemistry, and grafting provide versatile routes to functional polyisoprene. Dynamic covalent bonds and supramolecular interactions further enable reinforced, self-healing, reprocessable, recyclable, and stimuli-responsive elastomers. Importantly, their overall performance depends on balancing chain mobility, intermolecular interactions, network stability, and bond-exchange dynamics. Finally, emerging applications and challenges in multifunctionality and sustainability are discussed, providing molecular-design principles for next-generation functional polyisoprene elastomers.