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Title: Design, synthesis and material property investigation of degradable block copolymers prepared via the combination of ROCOP and ROP
Author: Zhu, Yunqing
ISNI:       0000 0004 7657 0122
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2017
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The thesis focuses on the synthesis of (multi)block copolyesters using combinations of the ring-opening copolymerization of anhydrides/epoxides and the ring-opening polymerization of lactones. All the new block copolyesters are fully characterized and in depth investigations of the materials' properties include evaluations as thermoplastic elastomers, shape memory polymers and polymers for biomedicine. Chapter 2 describes the polymerization of ɛ-caprolactone, using a di-zinc catalyst and various diols. A mixture of two polymer chain architectures is observed when using diols featuring secondary hydroxyls: these comprise chains which are either chain extended or chain terminated by the diol. This observation highlights the importance of analyzing the polymer architecture, the analysis may be achieved using a combination of NMR spectroscopic techniques, in the ring-opening polymerization of ɛ-caprolactone and refutes the common assumption that a single chain extended structure is produced in all cases. Chapter 3 uses di-zinc catalysts to selectively polymerize mixtures of lactones, epoxides and cyclic anhydrides to form multiblock copolyesters. By controlling the chemistry of the Zn-OP (P represents polymer chain) it is possible to select for a particular polymerization route and thereby allow access to multiblock copolymers having both alternating polyester blocks and aliphatic polyester blocks. The switchable catalysis is established to be generally applicable to a range of lactone/epoxide/cyclic anhydride combinations. The unusual catalyst selectivity is proposed to arise due to both kinetic and thermodynamic factors. Chapter 4 applies the selective catalysis to make multiblock copolymers which are subsequently chain-extended by reactions with diisocyanates. This method allows the preparation of amorphous multiblock copolymers comprising hard blocks from the ring-opening copolymerization of phthalic anhydride (PA) and cyclohexene oxide (CHO) and soft blocks from the ring-opening polymerization of ε-decalactone (DL). The obtained multiblock polymers function as thermoplastic elastomers, and shape memory materials, which are fully characterized and various application areas are proposed. Chapter 5 reports the synthesis of amphiphilic block copolymers, featuring hydrophobic poly(ɛ-caprolactone) blocks and hydrophilic blocks produced by the alternating copolymerization of maleic anhydride and epoxides featuring ether chains. The block copolyesters are designed to be both biodegradable and biocompatible. Block copolymers with different hydrophilic/hydrophobic ratios are processed to form self-assembled nanostructures in aqueous solutions, and show a range of different morphologies. The (bio)degradability, biocompatibility and drug release profiles are studies.
Supervisor: Williams, Charlotte Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral