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Natural biopolymers, such as DNA, RNA, and proteins, are discrete macromolecules possessing inherent biological functions attributed to their highly organized chemical structures. Their precision structures, in nature, are determined by the unique microstructures (or primary structures), including two major factors throughout the polymer chain: monomer sequence and stereoregularity. For a long time, polymer chemists have dedicated themselves to achieve such dual control during the synthesis of synthetic polymers in order to emulate such structurally perfect biopolymers. Despite the success of directly utilizing natural monomers (nucleotides and amino acids) to create such macromolecules, researchers are now ambitious to employ other non-natural monomers since their broad chemical diversity would excavate even more possibilities to sophisticate functions and applications in both biological and nonbiological niches. Unfortunately, limited methods have achieved the dual control including a newly disclosed method of iterative exponential growth, leaving a gap in terms of any radical addition methods utilizing the most diverse olefins as monomers.This thesis aims to address this gap, by synthesizing discrete and stereoregulated peptide mimics through successive and iterative radical addition of olefin monomers. With significant improvements to the previously disclosed photoinduced-RAFT single unit monomer insertion (Photo-RAFT SUMI) technique, the initial study has achieved perfect monomer sequence control by sequential and alternating insertions of two families of monomers, namely indene and maleimide. In which, two pentamers were successfully synthesized as examples by five iterative insertion reactions. Subsequent chain extension has demonstrated the “livingness” of the pentamers, illustrating the feasibility of further SUMI reactions to form longer discrete polymers. Subsequently, this promising synthetic method was successfully transformed to a flow reaction system.

The molecular weight distribution (MWD) has a significant impact on the properties of polymeric materials, however, the characterisation of polymer MWDs has been limited to statistical parameters such as the number-average molecular weight (Mn) and dispersity (Đ). These parameters do not fully express the features of polymer MWDs, thus limiting the ability to rationally design complex polymeric materials with tailored MWDs. Herein, a platform for the design and synthesis of arbitrary polymer MWDs is developed and experimentally validated. The platform is based on the description of polymer MWDs as a mathematical function, rather than individual statistical parameters. As such, the complete shape of arbitrary polymer MWDs can be designed using a developed software. The software requires only a calibration using model monomodal MWDs directly obtained from GPC to design theoretical MWD. Using this platform in conjunction with a flow-mediated polymerisation approach, a range of arbitrarily shaped polymer MWDs were successfully designed and prepared. Finally, complex triblock copolymer mixtures with tailored compositions and overall MWD were fabricated via a one-pass flow-mediated polymerisation using this computer-guided approach.

The rapid development of reversible deactivation radical polymerization (RDRP) enables the preparation of well-defined polymers with diverse topological architectures and functionalities. In particular, photoinitiated RDRP (photo-RDRP) has gained increasing attention in the past decade due to the use of environmentally friendly and economically benign external regulator, light. With the aid of photocatalysts, a great number of monomers could be polymerized to produce desired products under light irradiation. However, the uses of expensive transition metal complexes as photocatalysts lead to the significant rise in manufacture costs. Although many less expensive catalysts have been discovered, their toxicity and intense colour are still challenging. Therefore, catalyst separation processes are inevitable to obtain pure products. However, such purification processes are complicated and thus hinder the industrial applications. To this end, supported catalysts have been explored in photo-RDRP to facilitate the separation and reuse of the catalysts, hence accomplishing green and sustainable polymer synthesis. The body of work illustrates the benefits of supported catalysts in photo-RDRP as well as the robustness and versatility of these heterogeneous catalytic systems. Various innovative catalyst immobilization strategies have been proposed to prepare supported catalysts using cellulosic materials as solid supports. Afterwards, these supported catalysts were employed for photoinduced electron/energy transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization, in which various monomers were polymerized in different solvents under light irradiation to yield well-defined polymers with high end group fidelity. Moreover, facile separation and recovery of these supported catalysts were realized by simple squeezing and washing these catalyst immobilized composites, thus enable catalyst reuse with almost retained catalytic activity. More importantly, cott

Light has emerged as a prominent stimulus to both generate and manipulate polymeric materials across multiple length scales. Compared with other external stimuli, light-mediated approaches enable unprecedented control over when and where chemical transformations occur (i.e., spatiotemporal control). To date, the majority of established protocols rely on individual wavelengths of light (∼monochromatic), which does not harness the full potential of light-matter interactions. This review summarizes the nascent progress in utilizing multiple discrete wavelengths of light as a tool to create and alter soft matter. The concepts are structured in an effort to provide a roadmap to foster new directions in light-based polymer materials chemistry. The physical organic nature of wavelength selectivity is first detailed in the introduction to provide key mechanistic insight and lay a foundation for further developments. Next, an overview of chromophores that undergo various light-driven transformations is presented, followed by their utility in polymer platforms for controlled synthesis, property manipulation, and advanced manufacturing. The review concludes with a summary and outlook on the exciting future of wavelength-selective light-matter interactions in polymer science.

Polymeric nanoparticles have attracted substantial amount of interest in recent years due to its application in drug delivery, “smart” material and other fields. Polymeric nanoparticles can be prepared through a variety of techniques. In particular, polymerization induced self-assembly (PISA) is one of the most heavily studied techniques in making polymeric nanoparticles. With the successful implementation of Photo-initiated Reversible Addition-Fragmentation Chain-Transfer Polymerization (RAFT) onto PISA process such as Photoinduced Electron/Energy Transfer-Reversible Addition-Fragmentation chain Transfer Polymerization (PET-RAFT) PISA, nanoparticles can be synthesised under mild condition such as room temperature which avoids undesired side reaction with temperature sensitive compounds. Temporal control can be achieved by turning ON/OFF the visible light. Nanoparticle post-modification can be easily achieved through the switch of irradiation wavelength. Furthermore, the introduction of the oxygen quencher during the polymerization is able to restore the oxygen tolerance of the reaction system by reacting with the active singlet oxygen which was converted by the photocatalyst.This body of work exploits the benefit of performing PET-RAFT PISA process for the preparation of polymeric nanoparticles. Oxygen tolerance was further studied for the first time where the monomer itself was implied as the oxygen quencher. Continuous irradiation of light onto the nanoparticles with the presence of oxygen result in the oxidation of the thioether moiety group which result in disassociation of the nanoparticles. Such use of orthogonal wavelength to modify nanoparticle properties was further explored by introducing a UV responsive crosslinker. PET-RAFT PISA polymerization is conducted at 595 nm wavelength which is entirely decoupled with the crosslinking region at 365 nm. Hence synthesised nanoparticles can be subsequently crosslinked in-situ with the presence of oxygen.To further

The year 2020 marks the 100th anniversary of the first article on polymerization, published by Hermann Staudinger. It is Staudinger who realized that polymers consist of long chains of covalently linked building blocks. Polymers have had a tremendous impact on the society ever since this initial publication. People live in a world that is almost impossible to imagine without synthetic polymers. But what does the future hold for polymer science? In this article, the editors and advisory board of Macromolecular Chemistry and Physics reflect on this question.

Photo-controlled polymerisation uses a photo-excited photocatalyst (PC) to reversibly and deactivate the propagating species. Under regulation by light, photo-controlled polymerisation features temporal control, spatial control, sequence control and high level of selectivity/orthogonality between different systems, leading to a range of applications in advanced macromolecular synthesis such as surface patterning, 3D/4D printing, polymeric micelles, multiblock antimicrobial polymers with precise sequences and architectures. All these unique features of photo-controlled polymerisation are largely dependent on properties and functionalities of PCs. Traditionally, the selection and discovery of appropriate PCs rely heavily on a trail-and-error approach, where extensive experimental screening is needed to identify desired candidates. To reduce costs and circumvent the challenges in laborious experimental work, a rational design strategy emerged where a new PC in application to a photo-controlled polymerisation system can be designed based on understanding of the structure-property-performance relationships.This dissertation aims to enable and streamline a general fully computer-guided rational strategy of designing an efficient and functional PC for a commonly used photocontrolled polymerisation technique, namely photoinduced electron/energy reversible addition-fragmentation chain transfer (PET-RAFT) polymerisation. This thesis startsfrom using naturally evolved Chl a with various functional substituents and investigating its photocatalytic performance and functionalities in PET-RAFT polymerisation. General orientations for the design of PET-RAFT PCs were inspired from this natural design. On top of this, comprehensive structure-property-performance relationships were established at the quantum chemical level as guiding principles for rational PC design of PET-RAFT polymerisation, by combining experimental and computational studies on a library of halogenated xanthene dy

The widespread failure of antibiotics in the treatment of multidrug-resistant (MDR) or biofilm-associated infections is a critical global healthcare issue. Thus, there is an urgent need for the development of novel and effective antimicrobial agents or strategies. This dissertation explores the use of a synthetic antimicrobial polymer that consists of biocompatible oligo(ethylene glycol), hydrophobic ethylhexyl and cationic primary amine functional groups as a potential alternative to currently available antibiotics. In particular, this work investigates the advantages of combination therapy involving synthetic antimicrobial polymers and other antimicrobial agents as a novel therapeutic approach against bacterial infections.Firstly, a potent antibiofilm agent was developed by incorporating NO donor moieties into the structure of the synthetic antimicrobial polymer. The NO-loaded polymer showed dual-action capability as it could release NO to disperse biofilm, while the polymer caused membrane disruption. A synergistic effect in biofilm dispersal, planktonic and biofilm killing activities was observed against the Gram-negative bacteria Pseudomonas aeruginosa (P. aeruginosa).In a second approach, synergistic combinations containing the synthetic antimicrobial polymer and two antibiotics, namely doxycycline and colistin, were developed. Coadministration of these compounds significantly improved the bacteriostatic efficacy against wild-type and MDR P. aeruginosa strains. In addition, the combination involving doxycycline showed synergistic bactericidal activity, could hinder resistance development in P. aeruginosa and was capable of reviving susceptibility to treatment in the resistant strains.In a third approach, synthetic antimicrobial polymers in the form of core-shell micelles were used in combination with antimicrobial essential oils, namely carvacrol and eugenol, where the antimicrobial polymeric micelles played a secondary role as delivery vehicles for essential

The propagation polymer chains in RDRP can be isolated in the dormant form and be re-activated at chain ends to generate propagating radicals, which initiate subsequent chain extensions. Since the effect of remote substituents on kinetics decreases rapidly with their distance from the reaction site (chain ends), propagating radicals could be assumed to be only determined by the characteristics of terminal and penultimate units. Therefore, the chemical structure (substitution and stereochemistry) of dormant chain ends is crucial for the investigation of kinetics of RDRP. The investigation of stereochemical effect of dormant chain ends is challenging due to limited models which are highly accessible and able to represent long polymer chains. In this thesis, two ideal models (diastereomeric macro-RAFT agents with different chemical structures and two inherent diastereomers for each) were designed and prepared by single unit monomer insertion (SUMI) technology to examine their stereochemical effect on kinetics of RDRP. In the first work, diastereomeric CPDTC-Ane was synthesized by inserting the monomer anethole (Ane) into a trithiocarbonate, 2-Cyano- 2-propyl dodecyl trithiocarbonate (CPDTC) via SUMI. Two isolated diastereomeric oligomers, as the models for dormant polymer chains, were employed as initiators (chain transfer agents) for PET-RAFT (photoinduced electron/energy transfer reversible addition-fragmentation chain transfer) polymerization, respectively. Discriminatory photo-activation behavior was observed in separated diastereomer system with the consumption of Dia2 much faster than that of Dia1 under identical reaction conditions. However, such huge difference can be neutralized by chain transfer in mixed diastereomer system. The mechanistic insight into such interesting behavior was suggested with the aid of quantum chemical calculations. A bit more complicated system, diastereomeric CPDTC-St-PMI obtained by the insertion of two monomers (Styrene (St) and N-p