Effects of composition and architecture on the thermo-induced aggregation of thermoresponsive OEGMA-based block terpolymers
File(s)
Author(s)
Wang, Shaobai
Type
Thesis
Abstract
Although thermoresponsive block copolymers hold immense promise as nanocarriers and gelling agents for biomedical applications, their development is often hindered by a limited understanding of the structure-property relationship that governs their thermoresponsive behaviour. This thesis presents three studies on thermoresponsive block terpolymers synthesised via group transfer polymerisation (GTP) from oligo(ethylene glycol) methyl ether methacrylate (OEGMA) monomers, focusing on how chemical composition and chain architecture influence their thermo-induced aggregation.
The first study investigates ABC triblock terpolymers composed of hydrophilic OEGMA300 (the OEGMA monomer with an average molar mass of 300 g/mol, unit A), hydrophobic di(propylene glycol) methyl ether methacrylate (diPGMA, unit B), and less-hydrophilic di(ethylene glycol) methyl ether methacrylate (DEGMA, unit C) with varied compositions but a consistent molar mass. The cloud point temperature (Tcp) of the terpolymers was primarily governed by the poly(OEGMA300) content. Notably, one terpolymer exhibited a unique dual-stage transition, forming vesicular species upon heating, while others followed typical micelle-to-aggregate transitions.
The second study explores six symmetric pentablock terpolymers composed of OEGMA300 (unit A), n-butyl methacrylate (BuMA, unit B, hydrophobic), and DEGMA (unit C), covering all possible architectures at a fixed composition and molar mass. The Tcp of the terpolymers depended on micellar conformation, with higher values observed when poly(OEGMA300) formed the outermost layer. Additionally, the BCACB terpolymer exhibited superior gelation performance due to intermicellar bridging chains.
The third study focuses on BCACB variants with different compositions. A balanced ratio of hydrophobic and hydrophilic components was found to be essential for optimal gelation, while an excess of either component resulted in compromised gelation performance.
Overall, this thesis demonstrates the crucial roles of composition and architecture in the thermo-induced aggregation of OEGMA-based thermoresponsive block terpolymers, which may deepen the understanding of structure-property relationships in this type of polymer and facilitate their rational design for biomedical applications.
The first study investigates ABC triblock terpolymers composed of hydrophilic OEGMA300 (the OEGMA monomer with an average molar mass of 300 g/mol, unit A), hydrophobic di(propylene glycol) methyl ether methacrylate (diPGMA, unit B), and less-hydrophilic di(ethylene glycol) methyl ether methacrylate (DEGMA, unit C) with varied compositions but a consistent molar mass. The cloud point temperature (Tcp) of the terpolymers was primarily governed by the poly(OEGMA300) content. Notably, one terpolymer exhibited a unique dual-stage transition, forming vesicular species upon heating, while others followed typical micelle-to-aggregate transitions.
The second study explores six symmetric pentablock terpolymers composed of OEGMA300 (unit A), n-butyl methacrylate (BuMA, unit B, hydrophobic), and DEGMA (unit C), covering all possible architectures at a fixed composition and molar mass. The Tcp of the terpolymers depended on micellar conformation, with higher values observed when poly(OEGMA300) formed the outermost layer. Additionally, the BCACB terpolymer exhibited superior gelation performance due to intermicellar bridging chains.
The third study focuses on BCACB variants with different compositions. A balanced ratio of hydrophobic and hydrophilic components was found to be essential for optimal gelation, while an excess of either component resulted in compromised gelation performance.
Overall, this thesis demonstrates the crucial roles of composition and architecture in the thermo-induced aggregation of OEGMA-based thermoresponsive block terpolymers, which may deepen the understanding of structure-property relationships in this type of polymer and facilitate their rational design for biomedical applications.
Version
Open Access
Date Issued
2025-08-27
Date Awarded
01/12/2025
License URL
Advisor
Georgiou, Theonitsa
Publisher Department
Department of Materials
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)