Driven by the increasing interest in sustainable polymers, CO₂-based aliphatic polycarbonates have been intensively studied in the past years. To broaden their application horizon, a combination with other classes of polymers would allow tailoring the resulting product properties to meet growing expectations. Encouraged by this idea we successfully terpolymerized three different monomers, cyclohexene oxide (CHO), CO₂, and 2-vinylpyridine (2VP). The ring-opening copolymerization (ROCOP) of CHO and CO₂ is catalyzed at the β-diiminate (BDI) zinc moiety of the catalyst resulting in poly(cyclohexene carbonate) (PCHC). The yttrium metallocene site of the complex catalyzes the rare earth metal-mediated group-transfer polymerization (REM-GTP) of the Michael-type monomer 2VP towards poly(2-vinylpyridine) (P2VP). The two underlying polymerization mechanisms could be combined with the help of a novel heterobifunctional complex. Its two catalytic centers are connected with a pyridyl-alkoxide linker, which serves as initiating group at the zinc unit and is subsequently introduced to the yttrium metallocene via C-H bond activation. The sucessful synthesis of the targeted P2VP-block-PCHC terpolymer via sequential or one-pot procedure was confirmed by aliquot gel-permeation chromatography (GPC) analysis and solubility behavior tests. Moreover, 2VP was replaced with another Michael-type monomer, namely 2-isopropenyl-2-oxazoline (IPOx), to synthesize the terpolymer poly(IPOx)-block-PCHC, demonstrating the variability of the presented method. The resulting polymers, which combine aliphatic polycarbonates and polar, functional polyolefins, enable specific structural variations and terpolymer properties that would not be possible with the respective homopolymers.

Alina Denk

Technische Universitat Munchen Fakultat fur Chemie

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