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Title: Aliphatic and aromatic polyesters in the quest for degradable materials with improved physical properties
Author: Jeffery, Ben
ISNI:       0000 0004 9358 7380
Awarding Body: University of Bath
Current Institution: University of Bath
Date of Award: 2014
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Chapter 1: Background information on the polymers relevant to the research described herein is provided. The structure, properties and synthesis of polylactide (PLA), polyhydroxybutyrate (PHB), polymandelic acid (PMA) and other polyesters are discussed. Further to this, in-depth literature reviews of the copolymerisation of lactide (LA) with β-butyrolactone (BBL) and polyesters from the ring-opening polymerisation (ROP) of orthocarboxy anhydride monomers are provided. General literature reviews of both metal-based and organic catalysts for the ROP of cyclic esters are included. Chapter 2: This chapter documents a range of group 4 amine tris- and bis(phenolate) complexes and their utility in the ring-opening polymerisation (ROP) of the cyclic esters lactide (LA) and β-butyrolactone (BBL). The synthesis and characterisation of a range of complexes based on novel and previously reported amine-phenolate ligands of varying steric bulk is reported. A number of zirconium and hafnium complexes were found to be efficient initiators for both LA and BBL. The stereoselective ROP of both LA and BBL under similar conditions was achieved with a limited number of these initiators. The challenging copolymerisation of LA and BBL was also possible, leading to block-like copolymers that were found to be amorphous based on thermal analysis. Chapter 3: The synthesis and ring-opening of mandelic acid orthocarboxy anhydride (manOCA), the activated equivalent of mandelic acid, is discussed. It was found that typical combinations of organocatalysts and initiators such as 4-dimethylaminopyridine (DMAP) and primary alcohols gave poorly-controlled polymerisations. Specifically, racemisation of the monomer and transesterification led to low molecular weight atactic polymer. Decreasing the basicity of the pyridine catalyst was found to improve some aspects of the polymerisation but results were generally unsatisfactory. It was found that the combination of pyridine and themonomer’s parent acid, mandelic acid, yielded well-controlled reactions with predictable molecular weights and low polydispersities. Most importantly, a high degree of stereoretention of the monomer was achieved. For the first time, high molecular weight isotactic polymandelic acid (PMA) has been prepared. The glass transition temperature of these isotactic polymers was found to be ~105°C, the highest reported for PMA. Chapter 4: The experimental section gives general details of materials and analytical techniques as well as detailed preparations and characterisation data for all compounds synthesised. Procedures for the different polymerisation methods are included.
Supervisor: Davidson, Matthew Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available