Tailored living block copolymerization: Multiblock poly(cyclohexene carbonate)s with sequence control

A method for the living multiblock copolymerization of functionalized cyclohexene oxides and CO₂ was studied. β-Diiminate zinc catalysts have been used to copolymerize cyclohexene oxide derivatives with CO₂ to produce polycarbonates with narrow molecular weight distributions. A number of functionalized cyclohexene oxides (CHOs) were prepared which contained substituents at the 4-position, which is well separated from the propagating species during the copolymerization with CO₂. The substituted CHOs were copolymerized with CO₂ by catalyst. Polycarbonate derivatives containing vinyl, ketal, triethylsiloxy, hydrophilic, lipophilic, and fluorophilic groups were prepared and exhibited narrow molecular weight distributions. The living nature of CHO/CO₂ copolymerization catalyzed by the β-diiminate zinc complex was confirmed by the observation that Mn increases linearly as aliquots of CHO are added.