Since the 1950s, the global production of polymers has exponentially increased, particularly driven by polyolefins, now reaching over 400 million tons. As more polyolefins have been produced, the amount of waste generated from these has increased, specifically in single-use packaging materials. This thesis investigates a novel route to end-functionalised polyethylenes and di-block copolymers including a polyethylene block with the aim to improve the biodegradability of the most frequently used polyolefin.
Chapter 1 introduces the subject of pro-degradants for plastics, as well as the economical background and commercial significance of polyolefins.
Chapter 2 and 3 show the versatile functionalisation reactions that can be conducted starting from a di-alkyl zinc species in which each alkyl chain is HDPE (up to 68 carbons per HDPE chain). Functionalisation includes different halide end-groups (iodine and bromine with up to 99% functionalisation) and a terminal hydroxy functionalisation (with up to 78% functionalisation).
Chapter 4 investigates the use of hydroxy end-functionalised HDPE chains as macroinitiators for the nucleophilic ring-opening polymerisation of rac-lactide, leading to the controlled synthesis and characterisation of five PE-PLA di-block copolymers in different wblock compositions. The synthesis of polyethylene-polycaprolactone di-block copolymers was attempted (PE-PCL), but did not result in a controlled synthesis. PE-PLA di-block copolymers were further studied regarding their thermal- and degradation behaviour. The PLA-block degraded under humid conditions, leaving an unchanged PE-block behind.
Chapter 5 investigates the use of iodo-terminated polyethylene as a pro-degradant and as a potential UV-indicator for polyolefins. Chapter 6 provides additional data acquired within the course of this thesis to the reader.