Catalysts for the production of sustainable biopolymers

Abstract

The development of biodegradable plastics from sustainable sources is at the forefront of chemical research. One such example is the production of polylactide (PLA) via the ring-opening polymerisation (ROP) of the cyclic ester lactide (LA).Current industrial metal initiators utilised for the ROP of LA do not allow control over the stereochemistry of the resulting product. This thesis will investigatevarious initiators containing a variety of ligand sets for the ROP of rac-LA. Chapter 1 introduces the ROP of rac-LA, the mechanisms utilised and the methods employed for characterisation of PLA. A review of the current literatureof recent developments in the production of PLA via various metal initiators is also included. Chapter 2 reports the development of a series of group (IV) complexes containing various amine tris(phenolate) ligands, where the sterics and electronics have beenvaried. Such complexes were trialled for the ROP of rac-LA as well as the ROP of trimethylene carbonate (TMC). The ability of such initiators to producecopolymers of rac-LA/TMC and rac-LA/isosorbide was also investigated and discussed.Chapter 3 describes the synthesis of a range of group (IV) complexes containing Salalen ligands. The sterics of the ligands have been varied and the ability of theinitiators to initiate the ROP of rac-LA in a stereocontrolled fashion has been investigated. Furthermore, the complexes have been trialled for the degradation of PLA into methyl lactate, an important starting material in the production of LA. Chapter 4 investigates the development of Al(III) Salalen complexes for the ROPof rac-LA, where the sterics and electronics of the ligand have been varied. Kinetic investigations have been carried out to aid the understanding of the polymerisation process. Chapter 5 provides details of the reaction procedures for the synthesis of ligands, complexes and polymers. Kinetic procedures are also reported together with details of the analytical techniques employed.

Date of Award	11 Nov 2011
Original language	English
Awarding Institution	University of Bath
Supervisor	Matthew Jones (Supervisor)