Synthesis and characterisation of sequence-controlled multifunctional multiblock polyesters via quantitative one-pot iterative living ring-opening polymerisation (QOIL-ROP)
File(s)
Author(s)
Yu, Li
Type
Thesis
Abstract
Scientists have devoted enormous efforts towards developing various synthetic strategies for translating the defined sequences and specific functions of natural biomacromolecules to the synthetic polymers. However, the majority of sequence-controlled polymers fabricated through existing synthetic strategies are commonly non-biodegradable and chain-transfer agents and the halides (used in metal-mediated approaches) are generally attached to the polymer backbone in many current liquid-phase iterative strategies even after isolation, which restrict their potential applications across a wide range of scientific and technological fields. Moreover, some existing synthetic strategies rely on thorough purifications in each cycle. Herein, this thesis presents the work on a novel and simple strategy for scalable production of well-defined sequence-controlled multifunctional multiblock polyesters composing biocompatible and biodegradable backbones with site-selective functionality via the new quantitative one-pot iterative living ring-opening polymerisation (QOIL-ROP) method.
This new approach enables the synthesis of highly ordered multiblock copolyesters without any intermediate purification, allowing not only well-defined molecular weight but also nearly perfect unprecedented control of the microstructure in terms of the arbitrary distribution and chain length of each building block along the chain. To demonstrate the versatility of this approach, seven proof-of-concept polyesters were synthesised, including model quasi muliblock polyesters (A6A6A6A6A6 and A4A6A4A6A4) and multiblock copolyesters (A6B6A6B6A6, A4B6A4B6A4, A6B6A6A6B6, A6A6A6B6B6 and A6(B4C2)A6(B4C2)A6) with near-quantitative monomer conversions and relatively narrow molecular weight distributions for such complex structures in each cycle during the iterative polymerisation chain extension process. The sequence-controlled pentablock A6B6A6A6B6 copolyester was chosen to demonstrate scale-up synthesis on a multigram scale (∼56 g), further highlighting the robustness and commercialisation potential of the new strategy. This approach offers new perspectives for the design and synthesis of a new generation of artificial highly organised multifunctional macromolecular platform.
Moreover, through this robust approach, prominently tunable physicochemical and biodegradable properties as well as structural and site-selective functional complexities were successfully built into the water-soluble, multifunctional, sequence-controlled polyesters by precisely controlling the chain composition, monomer sequence and chain length. This would unlock promising diverse, real-world applications from healthcare to nanotechnology and information storage.
This new approach enables the synthesis of highly ordered multiblock copolyesters without any intermediate purification, allowing not only well-defined molecular weight but also nearly perfect unprecedented control of the microstructure in terms of the arbitrary distribution and chain length of each building block along the chain. To demonstrate the versatility of this approach, seven proof-of-concept polyesters were synthesised, including model quasi muliblock polyesters (A6A6A6A6A6 and A4A6A4A6A4) and multiblock copolyesters (A6B6A6B6A6, A4B6A4B6A4, A6B6A6A6B6, A6A6A6B6B6 and A6(B4C2)A6(B4C2)A6) with near-quantitative monomer conversions and relatively narrow molecular weight distributions for such complex structures in each cycle during the iterative polymerisation chain extension process. The sequence-controlled pentablock A6B6A6A6B6 copolyester was chosen to demonstrate scale-up synthesis on a multigram scale (∼56 g), further highlighting the robustness and commercialisation potential of the new strategy. This approach offers new perspectives for the design and synthesis of a new generation of artificial highly organised multifunctional macromolecular platform.
Moreover, through this robust approach, prominently tunable physicochemical and biodegradable properties as well as structural and site-selective functional complexities were successfully built into the water-soluble, multifunctional, sequence-controlled polyesters by precisely controlling the chain composition, monomer sequence and chain length. This would unlock promising diverse, real-world applications from healthcare to nanotechnology and information storage.
Version
Open Access
Date Issued
2020-09
Date Awarded
2020-12
Copyright Statement
Creative Commons Attribution Licence
License URL
Advisor
Chen, Rongjun
Publisher Department
Chemical Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)