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The synthesis and ring-opening polymerisation of novel cyclic esters from malic acid

By Ryan J. Pounder

Abstract

The work in this thesis is directed towards the preparation of cyclic ester\ud monomers using malic acid as a renewable resource. Their subsequent controlled\ud ring-opening polymerisation (ROP) to yield functionalised poly(ester)s is studied\ud and application in micellar self-assembly reported.\ud Chapter 1 reviews the many synthetic strategies that have been employed in the\ud preparation of functional glycolides, lactides, ε-caprolactones, δ-valerolactones\ud and β-propiolactones. Their subsequent polymerisation and applications are also\ud discussed.\ud Chapter 2 describes the improved synthesis of 3-(S)-\ud [(benzyloxycarbonyl)methyl]- and 3,6-(S)-[di(benzyloxycarbonyl)methyl]-1,4-\ud dioxane-2,5-diones, BMD and malide respectively, from L-malic acid. Controlled\ud organocatalytic ROP of BMD realised functional poly(glycolic acid-co-benzyl α-\ud malate)s (PBMD) with the choice of initiator proving important in determining\ud the resulting molecular weight. Successful hydrogenolysis of these poly(glycolic\ud acid-co-benzyl α-malate)s yielded hydrophilic poly(glycolic acid-co-α-malic\ud acid)s (PGMA) with subsequent degradation studies in H2O observing complete\ud degradation after six days.\ud In Chapter 3, the synthesis of 5-(S)- and 5-(R)-[(benzyloxycarbonyl)methyl]-1,3-\ud dioxolane-2,4-dione (L-malOCA and D-malOCA respectively) from L- and Dmalic\ud acid respectively is reported. ROP of malOCA with a range of pyridine\ud based catalysts enabled the synthesis of functional poly(benzyl α-malate)s\ud (PBMA). Mechanistic studies revealed the formation of several side products that\ud were eliminated via judicious choice of catalyst and column chromatography.\ud Subsequent hydrogenolysis realised hydrophilic poly(α-malic acid)s (PMA) with\ud degradation studies in H2O observing complete degradation after 10 days.\ud Chapter 4 reports the synthesis of novel amphiphilic PEO-b-PBMA block\ud copolymers by the ROP of L-malOCA or D-malOCA from PEO macroinitiators\ud with subsequent self-assembly realising polymeric micelles. Variation in both\ud size dimensions and stability of the micelles through changes in both the\ud hydrophobic and hydrophilic block lengths and their relative ratios was\ud demonstrated. The self-assembly of an equimolar mixture of homochiral PEO-b-\ud P(L-BMA) and PEO-b-P(D-BMA) resulted in the formation of stereocomplexed\ud polymeric micelles.\ud Chapter 5 provides a summary of the findings in chapters 2 – 4 with chapter 6\ud providing the corresponding experimental data

Topics: QD
OAI identifier: oai:wrap.warwick.ac.uk:34607

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Citations

  1. (2002). 24, 1033.Chapter 6 AppendicesChapter 6 7.1 Additional DLS data for chapter 4 7.2 PEO5K-b-P(L-BMA)10 polymeric micelles 7.3 PEO5K-b-P(L-BMA)25 polymeric micelles 7.3 PEO5K-b-P(L-BMA)40 polymeric micelles

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