Ring-Opening Polymerisation of Lactide and Other Related Monomers

Abstract

Polylactide (PLA) as a biodegradable and biocompatible polymer has had a lot of interest as an alternative to petrochemical-based polymers. PLA is synthesised from bio-renewable resources by the ring-opening polymerisation (ROP) of cyclic monomer lactide (LA). A variety of polymers can be synthesised with variations of microstructure and molecular weight. Initiators currently utilized in industry exhibit little stereocontrol, allowing a high demand for active stereoselective initiators. This thesis will discuss the synthesis of initiators, as well as investigations into co-polymerisations with other monomer. Chapter 1 initially introduces the synthesis of PLA, with a detailed discussion of possible polymer architectures along with previously reported initiators will be discussed and their influences on the polymeric physical properties. To date, the formation of lactide co-polymers and investigations into the morphology and microstructures of the resulting co-polymers. Chapter 2 describes a series of Group 4 isopropoxide complexes using inexpensive, commercially available ligands. Interesting coordination chemistry of such complexes will be discussed and their potential as initiators in the ROP of PLA will be investigated with kinetic studies to probe the control of architecture and molecular weights.Chapter 3 concerns the formation of lactide co-polymers using inexpensive, commercially available co-monomers. The study of block co-polymers by either one-pot or sequential polymerisations will be assessed and subsequent thermal properties analysed. Chapter 4 initially details the synthesis of cyclic monomers for lactide co-polymerisations. The ability to synthesise random or alternating lactide co-polymers in a one-pot synthesis will be probed with a variety of different cyclic monomers with varying stoichiometries and their properties examined. Chapter 5 reports the overall conclusions of the thesis and what work should be carried forward. Chapter 6 provides details analytical techniques, procedures and characterisations used throughout this thesis.

Date of Award	1 Jul 2014
Original language	English
Awarding Institution	University of Bath
Supervisor	Matthew Davidson (Supervisor)