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Title: The synthesis and ring-opening polymerisation of novel cyclic esters from malic acid
Author: Pounder, Ryan J.
ISNI:       0000 0004 2702 4555
Awarding Body: University of Warwick
Current Institution: University of Warwick
Date of Award: 2010
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The work in this thesis is directed towards the preparation of cyclic ester monomers using malic acid as a renewable resource. Their subsequent controlled ring-opening polymerisation (ROP) to yield functionalised poly(ester)s is studied and application in micellar self-assembly reported. Chapter 1 reviews the many synthetic strategies that have been employed in the preparation of functional glycolides, lactides, ε-caprolactones, δ-valerolactones and β-propiolactones. Their subsequent polymerisation and applications are also discussed. Chapter 2 describes the improved synthesis of 3-(S)- [(benzyloxycarbonyl)methyl]- and 3,6-(S)-[di(benzyloxycarbonyl)methyl]-1,4- dioxane-2,5-diones, BMD and malide respectively, from L-malic acid. Controlled organocatalytic ROP of BMD realised functional poly(glycolic acid-co-benzyl α- malate)s (PBMD) with the choice of initiator proving important in determining the resulting molecular weight. Successful hydrogenolysis of these poly(glycolic acid-co-benzyl α-malate)s yielded hydrophilic poly(glycolic acid-co-α-malic acid)s (PGMA) with subsequent degradation studies in H2O observing complete degradation after six days. In Chapter 3, the synthesis of 5-(S)- and 5-(R)-[(benzyloxycarbonyl)methyl]-1,3- dioxolane-2,4-dione (L-malOCA and D-malOCA respectively) from L- and Dmalic acid respectively is reported. ROP of malOCA with a range of pyridine based catalysts enabled the synthesis of functional poly(benzyl α-malate)s (PBMA). Mechanistic studies revealed the formation of several side products that were eliminated via judicious choice of catalyst and column chromatography. Subsequent hydrogenolysis realised hydrophilic poly(α-malic acid)s (PMA) with degradation studies in H2O observing complete degradation after 10 days. Chapter 4 reports the synthesis of novel amphiphilic PEO-b-PBMA block copolymers by the ROP of L-malOCA or D-malOCA from PEO macroinitiators with subsequent self-assembly realising polymeric micelles. Variation in both size dimensions and stability of the micelles through changes in both the hydrophobic and hydrophilic block lengths and their relative ratios was demonstrated. The self-assembly of an equimolar mixture of homochiral PEO-b- P(L-BMA) and PEO-b-P(D-BMA) resulted in the formation of stereocomplexed polymeric micelles. Chapter 5 provides a summary of the findings in chapters 2 – 4 with chapter 6 providing the corresponding experimental data.
Supervisor: Not available Sponsor: Engineering and Physical Sciences Research Council (EPSRC)
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QD Chemistry