Brannigan, Ruairi (2015) Design of novel monomers for applications in hydrolytically degradable thermoplastic elastomers. PhD thesis, University of Warwick.

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Abstract

This thesis explores the synthesis of novel monomers in the design of hydrolytically degradable materials with defined physical and chemical properties using a selection of coupling and polymerisation techniques. Chapter 1 introduces the concept of hydrolytically degradable polymers, namely polyesters, and exhibits the dynamic range of biomedical applications in which they might be utilised.

In Chapter 2, the organocatalysed ROP of a previously synthesised spirocyclic carbonate monomer bearing pendant benzylacetal functionality (PTO) and a novel spirocyclic carbonate monomer bearing pendant norbornene-acetal functionality (NTC) are described. The successful post-polymerisation modification of the norbornene functionality is demonstrated utilising a variety of addition reactions; the 1,3-dipolar cycloaddition of azides,inverse electron demand Diels-Alder reaction with tetrazines and the radical thiolene addition. Furthermore, the synthesis, self-assembly and pH-triggered degradation of graft copolymers, prepared by the thiol-ene addition of a thiol-terminated hydrophilic polymer to the hydrophobic polycarbonate backbone, is also described.

Chapter 3 describes the synthesis of A-B-A triblock copolyester-carbonates via the ROP of PTO (described in Chapter 2) initiated from an α,ω-dihydroxy poly(caprolactone) (PCL) macroinitiator, with varying molecular weights, yielding thermoplastic materials with superior tensile properties (elongation and Young’s modulus) to that of the PCL homopolymer. Furthermore, the alteration of PCLs thermal and degradation properties, as a consequence of the chain extension PTO, was also described.

In Chapter 4, the utilisation of the diol precursors to PTO and NTC (described in Chapter 2) as chain extenders for the organocatalysed synthesis of novel PCL-based thermoplastic polyesterurethanes (TPEUs) is reported. The successful post-polymerisation modification of the norbornene functionality is demonstrated utilising addition reactions optimised from Chapter 2. Furthermore, the mechanical, surface hydrophilicity and degradation properties of the TPEUs, before and after modification, are also described.

Chapter 5 describes the synthesis of novel diol chain extenders derived from natural amino acids, modified with carbamate and urea pendant groups, and their utilisation in the organocatalysed synthesis of novel PCL-based TPEUs. The modulation of physical and degradation properties by varying polymer composition and extender type were also described.

Chapter 6 provides a summary of the key findings of Chapters 2 – 5 and Chapter 7 provides the experimental methods of this thesis.

Item Type:	Thesis (PhD)
Subjects:	Q Science > QD Chemistry
Library of Congress Subject Headings (LCSH):	Monomers -- Synthesis, Thermoplastics, Elastomers
Official Date:	June 2015
Dates:	Date Event June 2015 Submitted
Institution:	University of Warwick
Theses Department:	Department of Chemistry
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Dove, Andrew P.
Sponsors:	Lubrizol Corporation
Extent:	xxvi, 185 leaves : illustrations (colour), charts
Language:	eng

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