The thesis describes the development, implementation and application of the first magnetic field time resolved infrared (MFTRIR) spectrometer, capable of studying the kinetics of radical reactions and the effect of weak magnetic fields upon them. The thesis commences with an overview of the theoretical concepts associated with free radicals and their reactions. The idea of the radical pair is presented and the magnetic field susceptibility of this species is discussed in the context of the radical pair mechanism. The construction and development of the MFTRIR spectrometer is then examined, highlighting the important design features and operational principles. The remaining chapters comprise an in depth analysis of the results obtained from the first studies performed using the spectrometer. The radical recombination kinetics and magnetic field dependence are studied for a range of precursor molecules with insights drawn into the structural factures that influence both the magnitude and form of the observed magnetic field effects. Later chapters explore the effects of the radical pair environment by investigating reactions in both isotropic solution and reverse micelle environments. A number of key findings are generated by this work. First is the excellent capability of the new instrument in measuring very small perturbations on radical reactions with weak magnetic fields. Second is the correlation between the size of the observed field effects and the magnetic parameters of the radicals. Third is the ability to remove the effects at very weak magnetic fields (approximately 2mT) without perturbing the effects at higher magnetic fields, through the selective removal of longer lived radical pairs.

The novel combined Electrochemical Quartz Crystal Microbalance-Probe Beam Deflection (EQCM-PBD) technique was used to study electroactive film dynamics and determine the individual contributions made by cation, anion and solvent species to the overall redox switching mechanism. The interpretation of the responses was extended to investigate the nature of the species transfer and film thickness changes in response to volume constraints. Studies of nickel hydroxide films in LiOH electrolyte show that hydroxide is the only detected ion transferring across the electrode/electrolyte interface to maintain electroneutrality. However, there is significant contribution made by protons, which are detected indirectly as H2O. The rigid nature of the film lattice constraints on the volume within the film and results, unusually in solvent transfer being forced into the same timescale as hydroxide ions. The mechanism for a- and b- phase redox switching differs only in the balance between hydroxide and proton (H2O) contributions to electroneutrality. The volume between layers in the film lattice defines this balance. The investigation of various polypyrrole and modified polypyrrole film systems exposed to a range of electrolytes highlights the effect of anion size on the predominant ion transfer maintaining film electroneutrality and the film volume changes accompanying this process in this non-rigid material. The variation in experimental timescale employed allowed further separation of the ion, salt and solvent transfers observed. The immobilisation of the polymeric polystyrenesulphonate (PSS) anion in the polypyrrole film matrix was shown to change the ion transfer properties of the film, which can be controlled as a function of electrolyte concentration. Salicylate anions were also used to create 'templated' PPy films, which indicated large solvent contributions. Surface roughness is shown to be a determining factor of the bulk properties of the 'templated' polymer film.

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The focus of this thesis is to synthesize and develop in-situ cross-linkable hydrophilic copolymers using multi-vinyl monomers via Reversible Addition-Fragmentation Chain Transfer Polymerisation (RAFT) for hydrogel applications. This thesis comprises six chapters described briefly below: Chapter 1 provides an introduction to the topics covered in the thesis. General fundamentals of main polymerisation techniques, basic concepts of the polymer chemistry, hyperbranched polymers, hydrogels and their applications are included. Chapter 2 describes the general experimental procedures and methodology used in this thesis, including the synthesis and characterisation of the precursors of the RAFT agents, final RAFT agents, disulphide diacrylate and the preparation of hydrophilic polymers by conventional and living/controlled radical polymerisation methods. Moreover, methods and analytical techniques used for the characterisation of compounds and polymers are described. The scientific background for interpretation and understanding of the results are also included in this chapter. Chapter 3 contains two subsections and focuses on the results and discussion on in-situ RAFT approach and its applicability in copolymerisation of vinyl monomers. In section 3.1, an in-situ technique of Reversible-Addition Fragment Chain Transfer (in-situ RAFT) polymerisation is developed. The kinetic studies on the in-situ RAFT polymerisations of methyl methacrylate (MMA) and styrene (St) through a facile one-pot and two-step approach are presented. Where, bis(thiobenzoyl)disulfide and 2,2'-azobis(isobutyronitrile) (AIBN) were used to generate RAFT agent 2-cyanoprop-2-yl dithiobenzoate in-situ at 80 oC, followed by further RAFT polymerisations of MMA or St at 65 oC. The kinetics of these in-situ RAFT polymerisations were studied using Gel Permeation Chromatography (GPC) under different reaction conditions in order to investigate the effects of solvent, temperature, and molar ratio of reactants. The experimental results demonstrated that this in-situ approach showed the similar controllability as conventional RAFT polymerisation in terms of the molecular weights and polydispersity of polymers obtained. The resultant polymers were characterized by proton Nuclear Magnetic Resonance spectroscopy (1H NMR analysis) and GPC, and were successfully used as macro RAFT agents for the preparation of PMMA-b-PSt block copolymers. In section 3.2, the in-situ approach developed in section 3.1 was successfully adopted to copolymerise poly(ethylene glycol) methyl ether methacrylate (PEGMEMA), poly(propylene glycol) methacrylate (PPGMA) and up to 30% of ethylene glycol dimethacrylate (EGDMA) as the branching agent. The characterisation and studies on the properties of prepared responsive copolymers are included. The resultant PEGMEMA-PPGMA-EGDMA copolymers from in-situ RAFT were characterised by GPC and 1H NMR analysis. The results confirmed the copolymers with multiple methacrylate groups and hyperbranched structure as well as RAFT functional residues. These water-soluble copolymers with tailored compositions demonstrated tuneable Lower Critical Solution Temperature (LCST) from 22 oC to 32 oC. The phase transition temperature can be further altered by post functionalisation through aminolysis of RAFT agent residues in polymer chains. Chapter 4 describes study on the conventional RAFT copolymerisation of PEGMEMA, PPGMA and bis(2-acryloyl)oxyethyl disulfide (DSDA). A series of polymerisations were carried out to prepare degradable PEGMEMA-PPGMA-DSDA hyperbranched copolymers, using 2-cyanoprop-2-yl dithiobenzoate as the RAFT agent. The molar feed ratios of monomers were varied to adjust polymer properties and manipulate LCST of the final polymers. The copolymers were tailored in order that they could be readily cleavable under mild conditions, physically crosslinked at body temperature and moreover chemically crosslinked with thiol crosslinker (QT) via Michael addition reaction. The reactions were monitored by GPC analysis, polymer compositions were calculated from peak integrations according to 1H NMR analysis. In addition, fabrication of hydrogels through Michael addition reaction using PEGMEMA-PPGMA-DSDA copolymers, swelling and degradation studies are also presented. Chapter 5 focuses on the synthesis of pH responsive dendritic hydrophilic polymers with tailored swelling profile by the use of RAFT polymerisation of 2-hydroxyethyl methacrylate (HEMA) and acrylic acid (AA). The copolymers were synthesised in the presence or absence of EGDMA. 4-Cyano–4-[(dodecylsulfanylthiocarbonyl)sulfanyl] pentanoic acid was used as the chain transfer agent (CTA), divinyl monomer EGDMA as the branching agent. The hydrogels from the resultant linear and dendritic copolymers demonstrated responsive properties at different pH values and temperatures in swelling studies. The responsive behaviours of these hydrogels have also been compared to the hydrogels prepared directly from crosslinking of AA, HEMA and EDGMA monomers. The resultant copolymers were characterized by GPC and 1H NMR analysis. Moreover, thermal properties of the polymers were evaluated by Thermo-Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). The degrees of swelling of the hydrogels were studied at 20 oC and 37 oC in phosphate buffer solution (pH 7.4) and water (pH 4 and pH 7). From these studies, it was found that the hydrogels from copolymers of AA and HEMA demonstrated thermal and pH responsive properties, which were significantly affected by the chemical composition and topological structure of polymer chains. Chapter 6 summarises the research presented in this thesis and draws the conclusions. Additionally, the vision and possible future work are included.

This work aimed to synthesise new bio-based solvents from bio-based platform molecules and dimethyl carbonate (DMC) as alternatives for traditional solvents. This work extended the scope of the DMC chemistry to including acid catalysts. Hansen Solubility Parameters in Practice (HSPiP) software was utilised as an effective tool to identify suitable bio-based solvents candidates.

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