Sustainable Process Design for Catalytic Polymerization to In-Chain Functionalized Polyethylenes

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Polyethylene is the mostly widely produced plastic in the world in terms of volume, used in many key technology areas. Its production efficiency is superior to that of most other plastics in terms of envi-ronmental impact. The linear hydrocarbon chains of polyethylenes (HDPE, LLDPE…) enable crystalline packing and provide excellent mechanical properties. The (micro)structures of PEs can be modified via a catalyst and/or the process conditions to obtain different levels of crystallinity. However, their chemically inert nature results in persistence for many decades when released to the environment. We have found a promising possibility to enhance the (photo)degradability of PE, and thus to improve the recyclability of these materials, by catalytically copolymerizing ethylene with carbon monoxide to generate a random distribution of keto-groups in the macromolecular chains. What’s more, enhanced photodegradability can be obtained without compromising the mechanical properties and processibility of the keto-PE materials. Gas phase polymerization can be considered the most advanced process for the generation of semi-crystalline polymers as it is solvent-free and enables a direct control of the resulting polymer particle morphology. Copolymerization of ethylene with polar monomers in general have been studied in solution polymerizations primarily, however, and gas phase polymerization has been neglected. This project will study the gas phase copolymerization of ethylene with carbon monoxide, which is a highly relevant reaction and also a particularly suited probe for copolymerizations of polar monomers, pursuing the following objectives: - Supporting methods for novel CO-compatible (cocatalyst-free) molecular polymerization catalysts by means of non-covalent binding to porous support materials will be explored (University of Konstanz, UKon). - Exploration of these catalysts in solvent-free gas phase copolymerizations to keto-polyethylenes particles, addressing amongst others support fragmentation and morphology control (Catalysis Polymerization Processes Materials, CP2M). - Understanding of the fundamental interactions between the catalytically active species of polar monomer copolymerization and the support, and resulting effect of support and gas phase conditions on the catalysts' behaviour (CP2M&UKon). - Investigation of photodegradability/recyclability and processibility/mechanical properties of keto-polyethylenes originating from gas phase polymerization (UKon). This synergistic collaboration is enabled by the unique expertise of CP2M in gas phase polymerization process, and of the Konstanz group in functional group-tolerant polymerization catalysts.