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TY - THES AU - Fuchs, Martin TI - Zur Nutzung von <i>N,O-</i>Hybridguanidin-Zink-Komplexen als multifunktionale Katalysatoren zur Implementierung einer biobasierten Kunststoffkreislaufwirtschaft PB - RWTH Aachen University VL - Dissertation CY - Aachen M1 - RWTH-2024-07170 SP - 1 Online-Ressource : Illustrationen PY - 2024 N1 - Veröffentlicht auf dem Publikationsserver der RWTH Aachen University N1 - Dissertation, RWTH Aachen University, 2024 AB - The use of synthetic plastics has become an indispensable part of our modern everyday lives. However, due to continued mismanagement at the end of the current linear plastics economy, these petroleum-based materials have become a massive threat to the environment. A promising solution is the use of bio-based and/or biodegradable materials, so-called bioplastics. Suitable candidates, such as the polyester polylactide (PLA), which is based on starch-rich plants and at the same time completely biodegradable, are not yet competitive with traditional petroleum-based, non-biodegradable mass plastics due to a cost-intensive production. Furthermore, the industrial production of PLA is not sustainable due to the use of the toxic catalyst tin octanoate, as toxic compounds can be released into the environment during biodegradation. To preserve the value of bioplastics at their end of life and to avoid plastic waste, the current linear plastics economy needs to be changed to a circular economy, idealy based on renewable resources. Herein, plastics are valorized after use in efficient recycling processes. Chemical recycling processes in particular offer a large potential here. In contrast to mechanical processes, plastics are depolymerized into smaller molecules, which can be used as a platform to produce new valuable chemical products or for the repolymerization of plastics without any loss of quality. To exploit the full potential of PLA in a sustainable, bio-based circular plastics economy, efficient, non-toxic catalysts are needed that are highly active in both the production and recycling of the bioplastics, becoming multifunctional tools to enable a biobased circular plastics economy. Therefore, in this dissertation, the polymerization behavior of N,O-hybridguanidine zinc catalysts, which are already known in the literature as non-toxic and robust catalysts for the ring-opening polymerization of lactide under industrially relevant conditions, was investigated in more detail. In kinetic studies, the effect of a co-initiator on the activity of these promising catalysts was investigated, with a focus on gaining knowledge about the initiation of polymerization. In addition, the catalytic activity of these catalysts was tested for the first time towards the chemical recycling of various polyesters via alcoholysis. The focus here was on the valorization of PLA with methanol to afford the lactic acid ester methyl lactate. In kinetic studies, the rate constant was determined which was used to gain knowledge about a structure-reactivity relationship. In addition, the influence of the molecular structure and concentration of the used alcohol on the reaction was tested as well as the suitability of the most active catalysts for industrial applications, including the recycling of petroleum-based polyesters. Therefore, these catalysts are well-suited tools to implement a biobased circular plastics economy. LB - PUB:(DE-HGF)11 DO - DOI:10.18154/RWTH-2024-07170 UR - https://publications.rwth-aachen.de/record/990149 ER -