Isoselective Polymerization of 1-Vinylcyclohexene (VCH) and a Terpene Derived Monomer S-4-Isopropenyl-1-vinyl-1-cyclohexene (IVC), and Its Binary Copolymerization with Linear Terpenes

The advancement of stereoregular polymerization techniques for linear 1,3-dienes has enabled the production of polymers with precise stereocontrol, influencing their physical and chemical properties significantly. While 1,3-butadiene and isoprene yield diverse stereoregular polymers, cyclic dienes have received less attention due to catalyst challenges and limited application in the rubber industry. However, the growing interest in bio-based monomers, particularly those derived from terpenes and terpenoids, has revitalized interest in cyclic monomers with conjugated double bonds. This study investigates 1-vinylcyclohexene (VCH) polymerization using [OSSO]-type titanium complexes 1-2, revealing significant regio- and stereoselectivity. Catalyst 2, incorporating cumyl substituents, demonstrates superior performance, yielding highly isotactic poly(VCH) with 3,4-insertion predominance. It is also shown that the polymerization of S-4-isopropenyl-1-vinyl-1-cyclohexene (IVC), a bio-based monomer, results in a highly isotactic polymer. Finally, the copolymerization results of IVC with two linear terpenes to obtain copolymers derived entirely from renewable sources are also reported.