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Abstract
In recent years, polymeric nanoparticles (PNPs) have found diverse applications in fields such as diagnostics, catalysis and drug delivery. However, current methods to synthesize PNPs can be limited by the scalability of the synthesis and/or the reproducibility of particle size and shape. Polymerization-Induced Self-Assembly (PISA) is a technique that uses a living polymerization process to drive the self-assembly of PNPs to occur during the polymerization. Compared to conventional methods, the PISA process allows for PNP synthesis at much higher polymer concentrations (up to 50 wt%) in addition to providing more reproducible access to nanoparticles of different morphologies. Normally, the PISA process is conducted under thermally initiated reversible addition-fragmentation chain transfer (RAFT) dispersion polymerization conditions. In contrast, this dissertation explores the application of various visible light photopolymerization techniques to drive the PISA process (Photo-PISA). In particular, this work investigates the advantages of visible light initiated photopolymerization techniques which generally proceed under mild conditions and enable a fine degree of external control over the polymerization by variations in irradiation wavelength, intensity and time.
This body of work demonstrates that the Photo-PISA approach can perform PNP synthesis under mild room temperature conditions and in environmentally friendly solvents. A high degree of temporal control over the nanoparticle shape is observed which facilitates the isolation of specific morphologies. Interestingly, manipulation of extrinsic parameters such as the irradiation wavelength and/or intensity can be used to favor the formation of different morphologies. In addition, by performing Photo-PISA at room temperature, worm-like micelles can be readily isolated by monitoring the reaction viscosity during the polymerization.
When the photocatalyst, ZnTPP is employed to initiate the Photo-PISA process, it can also be encapsulated into the nanoparticle after the polymerization and act as a light activated drug for applications in photodynamic therapy. Finally, under certain conditions, it is demonstrated that the Photo-PISA process can be exploited to perform PNP synthesis without the usual deoxygenation procedures. This allows for self-assembled PNPs to be synthesized at ultralow volumes and in parallel with a view towards applications in high throughput synthesis and structure-activity screening.