Self-assembled block copolymers: micelles, polymersomes and gels
File(s)
Author(s)
Feng, Bailin
Type
Thesis
Abstract
Self-assembled polymers (micelles, polymer vesicles/polymersomes, and gels) are promising biomaterials for many biomedical and manufacturing applications like drug delivery, tissue engineering and 3D printing. The focus of this thesis was to investigate the drug delivery of polymersomes and how the gelation behaviour of thermoresponsive polymers is affected by the polymer structure. Most of the polymers in this thesis have been successfully synthesised by Group Transfer Polymerisation (GTP). Specifically,
i) In the first project, the hydrophilic monomer poly(ethylene glycol) methyl ether methacrylate (PEGMA, A) was combined with hydrophobic monomer methyl methacrylate (MMA, B) by GTP to obtain AB diblock copolymers and ABA triblock copolymers. The composition of each block was systematically varied. The polymersomes were characterised by Dynamic Light Scattering (DLS) and Transmission Electron Microscopy (TEM). Finally, the fluorescein sodium was encapsulated in the polymersomes and release study was also investigated.
ii) In the second project, a new series of ABC triblock copolymers were successfully synthesized via GTP based on PEGMA (A), 2-phenylethyl methacrylate (PhEMA, B) and di(ethylene glycol) methyl ether methacrylate (DEGMA, C). The composition of each block was systematically varied. Graphene was also mixed with the most promising thermoresponsive polymer to investigate if a stable structure can be successfully printed.
iii) The third project focused on investigating if the five different alkyl methacrylates, specifically, MMA, ethyl methacrylate (EtMA), propyl methacrylate (ProMA), n-butyl methacrylate (BuMA) and n-hexyl methacrylate (HMA) as B block in ABC triblock polymer PEGMAx-b-Alkyl methacrylatey-b-DEGMAz affected the thermoresponsive behaviours of aqueous polymer solutions. Therefore, ABC triblock copolymers were successfully synthesized via GTP based on PEGMA (A), alkylmethacrylate(B) and DEGMA(C) and varying compositions. The self- assembly and thermoresponsive behaviour of their aqueous solution was investigated.
In conclusion, the diblock polymer PEGMA13-b-PMMA60 and triblock polymers PEGMA13-b-PMMA20-b-PEGMA13, PEGMA11-b-PMMA30-b-PEGMA11 and PEGMA7-b-PMMA60-b-PEGMA7 all can self-assembly into the structure of a polymersome and fluorescein sodium can be successfully encapsulated and released. The most promising thermogel from the second project PEGMA14-b- PhEMA15-b-DEGMA7, was mixed with (10 w/w%) graphene to form the ink and a stable structure is successfully printed based on the ink. In the third project, for the same composition of each block of polymers with different alkyl methacrylates, the gels form at a lower temperature when the alkyl methacrylate has a longer side chain.
i) In the first project, the hydrophilic monomer poly(ethylene glycol) methyl ether methacrylate (PEGMA, A) was combined with hydrophobic monomer methyl methacrylate (MMA, B) by GTP to obtain AB diblock copolymers and ABA triblock copolymers. The composition of each block was systematically varied. The polymersomes were characterised by Dynamic Light Scattering (DLS) and Transmission Electron Microscopy (TEM). Finally, the fluorescein sodium was encapsulated in the polymersomes and release study was also investigated.
ii) In the second project, a new series of ABC triblock copolymers were successfully synthesized via GTP based on PEGMA (A), 2-phenylethyl methacrylate (PhEMA, B) and di(ethylene glycol) methyl ether methacrylate (DEGMA, C). The composition of each block was systematically varied. Graphene was also mixed with the most promising thermoresponsive polymer to investigate if a stable structure can be successfully printed.
iii) The third project focused on investigating if the five different alkyl methacrylates, specifically, MMA, ethyl methacrylate (EtMA), propyl methacrylate (ProMA), n-butyl methacrylate (BuMA) and n-hexyl methacrylate (HMA) as B block in ABC triblock polymer PEGMAx-b-Alkyl methacrylatey-b-DEGMAz affected the thermoresponsive behaviours of aqueous polymer solutions. Therefore, ABC triblock copolymers were successfully synthesized via GTP based on PEGMA (A), alkylmethacrylate(B) and DEGMA(C) and varying compositions. The self- assembly and thermoresponsive behaviour of their aqueous solution was investigated.
In conclusion, the diblock polymer PEGMA13-b-PMMA60 and triblock polymers PEGMA13-b-PMMA20-b-PEGMA13, PEGMA11-b-PMMA30-b-PEGMA11 and PEGMA7-b-PMMA60-b-PEGMA7 all can self-assembly into the structure of a polymersome and fluorescein sodium can be successfully encapsulated and released. The most promising thermogel from the second project PEGMA14-b- PhEMA15-b-DEGMA7, was mixed with (10 w/w%) graphene to form the ink and a stable structure is successfully printed based on the ink. In the third project, for the same composition of each block of polymers with different alkyl methacrylates, the gels form at a lower temperature when the alkyl methacrylate has a longer side chain.
Version
Open Access
Date Issued
2022-07
Date Awarded
2022-11
Copyright Statement
Creative Commons Attribution NonCommercial Licence
License URL
Advisor
Georgiou, Theonitsa
Porter, Alexandra
Publisher Department
Materials
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)