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Presence of sterically demanding substituents around Lewis acids (LAs) and bases can preclude the required close contact to form classical Lewis pair adducts. These instead form frustrated Lewis pairs (FLPs) which can be used for the activation of various small molecules, including H2, CO2, diethyl azodicarboxylate (DEAD) and cyclic ethers. Applying this concept into polymeric frameworks results in the formation of a novel class of stimuli-responsive polymers, which demonstrated significant potential as small molecule triggerable polymer gels. This thesis provides the first insights into the rheology of poly(FLP) networks. It provides a detailed rheological characterisation of the DEAD-triggered poly(FLP) gels, which were shown to behave similarly to the supramolecular assemblies linked by non-covalent bonds. It was shown that the FLP-DEAD crosslinks are highly dynamic, and the self-healing occurred immediately after the damage cycles, with up to 91% recovery of the original moduli values within 15 mins. It was found that an increase in crosslink density (4 to 7 mol%) increased the stiffness of the networks 3-fold, whereas switching the polymer backbone from styrene to methyl methacrylate resulted in easier chain rearrangements, thus higher number of effective crosslinks. Inspired by these promising results, an attempt was made to ease access to the preparation of poly(FLP)s by synthesising a range of accessible polymeric LAs with high Lewis acidity moieties which usually require challenging synthetic steps. This part reports the syntheses of poly(styrene-co-bis(pentafluorophenyl)pentafluorophenylborinate) and poly(styrene-co-cyclohexylbis(pentafluorophenyl)borane), 1, as well as the preparation of a tris(pentafluorophenyl)borane-mimicking functional monomer and the subsequent attempts to polymerise it. Finally, 1 was matched with poly(styrene-co-triphenylphosphine) to explore its potential as poly(FLP)s. Although earlier poly(FLP) networks relied entirely on the activation of DEAD, this substrate scope was expanded to cyclic ethers, which also triggered gelations. It was shown that the steric and electronic properties of the ethers directly affect the extent of crosslinking and can be used to tune the mechanical properties of the gels. Unlike the DEAD-triggered poly(FLP)s, these systems behaved similarly to the covalently crosslinked polymer networks, suggesting the strong effect of FLP interactions on the overall rheology of the polymer networks as well as the versatility of the poly(FLP)s as platforms for polymer networks with tuneable mechanical properties.

In recent years the use of renewable feedstocks, instead of fossil fuels, for the production of industrially important chemicals has drawn increasing attention. An interesting aspect of moving towards low-carbon technologies is the use of carbon dioxide as an appealing carbon source as a cheap, non-toxic and abundantly available C1 building block. This thesis is divided in two parts in which the activation and the catalytic transformation of small molecules, such as CO and CO2, have been studied with an actinide, a rare-earth and a transition metal catalysts. An introduction examining the chemistry trends across d- and f-block is given in chapter one. Part A: Chapter two reviews important uranium and yttrium complexes in the literature that successfully undergo small molecule activation. Boroxide ligands and their properties are introduced and selected examples are provided. Chapter three reports the synthesis and characterisation of a new U(III) boroxide complex and its reactivity towards small molecules. The synthesis and characterisation of two different yttrium boroxide complexes is reported and the reactivity with small molecules is compared. Part B: A very interesting use of carbon dioxide is the catalytic formation of acrylates with alkenes. Chapter four reviews the catalytic transformation of carbon dioxide and ethene to acrylate, focusing on nickel and palladium catalyst and on the mechanism and the formation of a lactone as an intermediate species. Chapter five describes the catalytic screening of different parameters such as catalyst precursor, ligands and temperature on the catalytic formation of acrylate using nickel and palladium catalysts. Chapter six presents the detailed experimental methods used in part A and B.

Understanding and characterising the behaviour of polymers at surfaces is of great fundamental interest, in addition to being vitally important for many applications. Composite materials, films and coatings, functional membranes, and nanoelectronics are only a few examples of applications which rely on polymers functioning at surfaces. The interactions between polymers and surfaces are extremely influential in governing the overall bulk properties of materials and products. Despite this, the behaviour of polymers at surfaces is not fully understood and there are many unexplored areas in this field of research. Atomic force microscopy (AFM) is a technique which can image features with a high spatial resolution down to a sub-nanometre scale. It can accurately image a variety of polymer nanostructures on surfaces such as droplets, networks, thin films, and even single chains. AFM can also be used in a mode of operation called force spectroscopy which generates information regarding the strength of adhesion between different materials with a piconewton force resolution. It can be used to measure the magnitude of interaction forces between single polymer chains and surfaces. The primary aim of this study was to characterise the behaviour of poly(styrene-cobutadiene) random copolymers on various surfaces at the nanoscale using AFM techniques. Poly(styrene-co-butadiene) is heavily utilised within industry, particularly in the manufacturing of automotive tyres where it is mixed with carbon black to form a robust composite material. This study is the first work to provide a comprehensive report on the morphology of poly(styrene-co-butadiene) nanostructures on various surfaces, under different experimental parameters. Furthermore, it is the first time where the specific interactions and adhesion between poly(styrene-co-butadiene) and various surfaces have been examined using AFM force spectroscopy. A systematic study was carried out which investigated the structural behaviour of adsorbed poly(styrene-co-butadiene) random copolymers on mica and graphite surfaces using AFM imaging. A large range of concentrations and molecular weights allowed investigations and discussions of many phenomena such as thin film formation (and dewetting), networks, spherical cap nanodroplets, and single chain conformations. Polymer morphology was generally more consistent on the mica, and varied significantly on graphite. The contact angles of the nanodroplets on the mica surface were shown to be size dependent by a specific trend irrespective of molecular weight. A minimum contact angle was observed for droplets with radii ranging from 100 - 250 nm across each molecular weight. This was due to influences from line tension, changes in elastic modulus, and surface heterogeneities. On the graphite, the nanostructures exhibited distinct ordering at the nanoscale. The features reflected the crystalline symmetry of the graphite by orientating themselves at intervals of 60° due to π-π stacking interactions. The ordering was extremely precise at the lowest concentration and became less defined at higher concentrations, but remained statistically significant. An AFM force spectroscopy study was implemented in order to investigate the adhesion and specific interactions between poly(styrene-co-butadiene) and mica, silicon, and graphite substrates. AFM tips were dip coated into polymer solutions to physically adhere polymer chains to the surface of the tips at varying molecular weights and surface coverages. Polymer chains were also adhered to AFM tips using force spectroscopy techniques. The results showed that capillary forces were increasing polymer/substrate adhesion on the more hydrophilic substrates. Single chain desorption events did occur, but had a very low probability. The experimental system was redesigned to reduce capillary effects and increase desorption events. Thin polymer films were deposited onto each substrate using dip coating and the AFM tips were left blank. The results revealed that capillary forces were eliminated using this system and the probability of single chain desorption events occurring was extremely high. It was demonstrated that the specific interactions between poly(styrene-co-butadiene) and graphite were the strongest of the three substrates due to π-π stacking interactions and van der Waals forces.

Polymers of intrinsic microporosity (PIMs) owe their microporosity to their rigid and contorted structure which prevents efficient space packing. Their microporosity and processability make them attractive for many industrial applications, such as heterogeneous catalysis, gas separation membranes, hydrogen storage and adsorbents for organic compounds. Our goal in this project is to broaden the spectrum of PIM structures by preparing novel PIMs with potential for different industrial applications but focusing on gas separation membranes. Characterisation of the novel polymers was achieved to establish their chemical and physical properties including solubility, surface area, thermal stability and their molecular weight. In some cases, casting the resulting PIMs from solution enabled the formation of self-standing films which could then be analysed for their ability to separate different gas mixtures. Three different types of PIM were targeted during the PhD programme. Firstly, the preparation of Tröger's base (TB) containing hypercrosslinked polystyrene was attempted. The first step was the nitration of polystyrene by using different reaction conditions, with the aim to introduce the highest possible number of nitro groups, followed by the reduction of nitropolystyrene to the aminated polystyrene. Finally, hyper-crosslinking of the amino-polystyrene was attempted by formation of TB units between polymer chains. Secondly, new ladder and network PIMs derived from different catechols monomers with 2,3,7,8-tetrafluoro-5,5',10,10'- tetraoxidethianthrene were synthesised. This thiathrene-based rigid monomer increases the distances between two consecutive "sites of contortion" within the polymer chains and provides sulfonyl functional groups, which may influence the adsorption and gas separation properties of the resulting polymers. Thirdly, a series of novel microporous polyimides (PIMPIs) were prepared using different diamine monomers and thiathrene-based dianhydride monomers. All polymers were characterized by using NMR, IR spectrometers and their chemical and physical properties were measured using a variety of techniques. In addition, for some polymers successful film formation via casting from solution allowed the measurement of their gas permeability to assess their ability to separate gas mixture. All chemical procedures for the synthesis of monomers and polymers, properties of the resulting polymers and comparisons with existing polymers are described in this thesis.

The olefin metathesis of oleochemicals is a promising method to produce valuable compounds from renewable feedstocks. However, several issues hinder the industrial application of this methodology such as low catalyst turn over number (TON), selectivity and substrate conversion. Using the ethenolysis of methyl oleate (MO) as a model reaction, the optimisation of this valuable process was investigated. A range of commercially available metathesis pre-catalysts were examined and evaluated based on several key criteria: conversion of methyl oleate, selectivity towards ethenolysis over self metathesis and TON. After identifying the best performing catalyst (Hoveyda-Grubbs 1st generation pre-catalyst), the remaining reaction conditions (ethylene pressure, catalyst loading, reaction time and temperature) were investigated using design of experiments. The optimised conditions obtained gave excellent conversion of methyl oleate. It is proposed that the remaining issues of selectivity and TON may be improved by applying a membrane separation technique. The initiation mechanism of Grubbs 3rd generation pre-catalyst (GIII) was also investigated to unravel the difference in selectivity compared to Grubbs 2nd generation pre-catalyst (GII) (12 % and 17 % respectively), as both pre-catalysts should give the same catalytically-active alkylidene species. The model reaction of GIII with ethyl vinyl ether (EVE) was followed by stopped-flowed UV spectroscopy (SF-UV). Due to the extreme sensitivity of the GIII pre-catalyst, substantial optimisation of the instrument set-up was required in order to achieve reproducible kinetic data and anaerobic conditions. The model reaction was studied by SF-UV at different concentrations of EVE and the effect of 3-bromopyridine addition was also investigated. The kinetic data suggests that the initiation of GIII proceeds via a combination of associative and dissociative pathways. Accordingly, two different alkylidene active species are able to react with an olefin (MO) when GIII is used as pre-catalyst compared with one alkylidene species when GII is employed as pre-catalyst. This is proposed to be crucial for the difference in selectivity between GII and GIII pre-catalysts in the ethenolysis of MO.

Biopolymers such as proteins, nucleic acids and polysaccharides are essential components in living systems and enabling the modification and modulation of various cellular functions and cellular behaviour. Many synthetic polymers have been used in a cellular context mimicking these natural polymers. However, few studies have focused on polymerisation chemistry within the complicated biological environment inside cells. In the first part of this thesis, a new method of synthesising synthetic polymers in cells was developed, enabling the introduction of artificial components to tune cellular behaviour. Several biocompatible acrylic and styrene monomers were polymerised intracellularly and shown to control the cell cycle, alter the cytoskeleton and influence cell motility. Moreover, the introduction of specific functional monomers enabled the in situ formation of fluorescent polymers and nanoparticles which may contribute to further applications such as fluorescent imaging and cargo delivery. Chemical modifications of native biomacromolecules provides access to novel functions such as macromolecule based cargo delivery and imaging probes. In the second part of this thesis, linear acrylamide polymer scaffolds, bearing norbornene reactive centres for tetrazine ligation and a hexahistidine tag for ease of purification, were synthesised and conjugated to a clinical antibody. This enabled the selective labelling of cancer cells with amplified fluorescent signal. Simultaneously "switching on" and amplification of a fluorescent signal "in situ" were achieved by utilising a tetrazine quenched fluorophore, reacting with norbornenes on the polymer-antibody conjugate. This fluorescence signal amplification method has the potential to improve real-time tumour detection and fluorescence-guided surgeries while the amplification strategy can be expanded to enhance radio-therapy performances.

The work described in this thesis concerns the synthesis of actinide complexes and their reactivity towards small unsaturated molecules. Complexes bearing tetraphenoxide, borohydride and boroxide ligands have been evaluated. Additionally, work towards the synthesis of heterobimetallic uranium transition metal complexes and their applications in catalysis is discussed. Chapter one reviews important organoactinide complexes reported in the literature which effect chemical transformations on small unsaturated substrates. Actinide complexes supported by aryloxide or borohydride ligands are reviewed, along with actinide complexes in which metal p-arene interactions are present. Chapter two reports the synthesis and characterisation of a set of tetraphenol ligands, in addition to a number of attempted synthetic routes to tetraphenol ligands with alternate substitution. The chemistry of those tetradentate aryloxide ligands is introduced with bimetallic uranium(IV) and thorium(IV) complexes using different An(IV) and U(III) precursors. Chapter three reports the synthesis and characterisation of monometallic uranium and thorium complexes using a tetraphenol ligand. The varying chemistry between the two similar An(IV) ions, where the uranium complexes exist as a mixture of oligomers and the thorium complexes remain as well defined mononuclear complexes, is discussed within. A range of base adducts of mononuclear actinide complexes are reported, including a thorium trimethylsilylazide complex, a rare example of a metal organoazide. Chapter four describes the synthesis of homoleptic boroxide and heteroleptic borohydride complexes of uranium(III). The reactivities of these complexes with small unsaturated molecules are assessed, including the reaction of a low coordinate uranium(III) boroxide complex towards CO2 to provide a dinuclear uranium carbonate bridged complex. Chapter five introduces work towards heterobimetallic uranium transition metal complexes carried out in the Arnold group. The application of these complexes towards ring opening polymerisation chemistry is discussed in addition to investigations into the incorporation of transition metals into uranium(IV) complexes. Chapter Six presents the detailed experimental methods used to carry out this research.

Polyesters have been realised as a viable replacement for slow or non-degrading petroleum derived polymers. A variety of aliphatic polyesters, e.g. poly(lactic acid), have received a lot of attention because they are produced from renewable feedstocks and have the ability to biodegrade and bioassimilate. Poly(lactic acid)'s broader family, poly(α-hydroxy acid)s, have been produced with a wide variety of properties, that has given polyesters the potential for a more diverse range of applications. However, their synthesis has proven difficult. This thesis investigates a family of 1,3-dioxolan-4-ones as a monomer source to ease difficulties in current synthetic routes. Polymerisation of the parent 1,3-dixoxolan-4-one was tested. The copolymerisation of Llactide and 1,3-dioxolan-4-one was conducted with various monomer feedstocks. Ringopening polymerisation of 1,3-dioxolan-4-one led to the formation of paraformaldehyde as a polymerisation by-product. The copolymerisation was found to be best controlled when using a coordination-insertion type catalyst. 1,3-dioxolan-4-one was also copolymerised with ε-caprolactone and β-butyrolactone to produce copolymers with various compositions. The formation of poly(lactic acid) and poly(mandelic acid) from 5-methyl-1,3-dioxolan- 4-one and 5-phenyl-1,3-dioxolan-4-one was investigated. Poly(lactic acid) and poly(mandelic acid) were synthesised with either isotactic or atactic tacticities. Molecular weights were found to be lower than the expected values. A variety of MeAl(salen) catalysts were explored for the polymerisation of 5-methyl-1,3-dioxolan-4-one and catalysts ligated with tertiary-butyl substituted salens were found to have higher rates of polymerisation and reached high conversions. Altering the diimine bridge in the ligand led to variations in rates of polymerisation and molecular weights. The cause of the decrease in molecular weight was found to be caused by a side reaction. The side reaction was bypassed by polymerising 2,2,5- trimethyl-1,3-dioxolan-4-one and 2,2-dimethyl-5-phenyl-1,3-dioxolan-4-one to form poly(lactic acid) and poly(mandelic acid), respectively, with the expulsion of acetone. The scope of 1,3-dioxolan-4-ones capable of being polymerised to form poly(α-hydroxy acid)s was expanded to include iso-propyl, cyclohexyl, normal-butyl, iso-butyl, propargyl, chloromethyl and benzyloxymethyl substituents at the five position. The glass transition temperatures accessible from this synthetic route was expanded (22-105 °C). Kinetic experiments revealed the impact of the substituents steric bulk on the rate of polymerisation and points toward a coordination-insertion mechanism. Poly(lactic acid-co-glycolic acid) was copolymerised with 5-propargyl-1,3-dioxolan-4-one to incorporate alkynyl functionality and hence Raman spectroscopy showed the polymer had a distinct peak at 2128 cm-1. Following post-polymerisation modification of poly(lactic acid-co-3-chloro-2-hydroxypropanoic acid) copolymers, acrylate functionalised polymers were produced. The copolymers were shown to be capable of crosslinking poly(α-hydroxy acid) and poly(methyl methacrylate).

The chapter one introduces the reported examples of rare earth metal (RE) complexes with different oxidation states. It also reviews the synthesis and reactivity study of N-heterocyclic carbene (NHC) supported transition metal and RE metal complexes. Chapter two focusses on the synthesis and characterisation of a series of tetraaryloxide Ce and Pr complexes. With the reaction of bulky tetraphenol proligand H4LR(R = P, PT, M) with four equivalents of KN"(N" = N(SiMe3)2), a dimerised complex of [K4LP]2(thf)11 was synthesised and characterised. The salt metathesis reactions of this complex with RECl3(thf)2 afford bimetallic aryloxide complexes of K2L2RE2(thf)11 (RE = Ce, Pr), which display divergent structures under different conditions. Reactions of the CeIII complex of K2L2Ce2(thf)11 with a variety of oxidants(I2, CuCl2 and O2, etc.) lead to the oxidation of CeIII to CeIV, affording purple ceric dimer of L2Ce2. The reaction of the PrIII complexes with I2 under 60 °C affords a mixture from which PrIII iodide (LPr2I2) has been isolated and characterised. This chapter also discusses the reactivity of the bimetallic aryloxide complexes towards different substrates, such as MeLi, KC8 and KBn (Bn = benzyl). Bimetallic complexes of L(REX)2(py)8 (RE = Ce, Pr; X = Cl, BH4) are synthesised and characterised. The preliminary study on the copolymerization of cyclohexene oxide (CHO) and CO2 is conducted for CeIII and PrIII complexes. Chapter three details the work on two different types of NHC ligand. The first ligand is the β-ketoimidazolinium salts H2LBr {L = RC(O)CH2{CH[NCH2CH2NMes], R = tBu, naphth} which reacts with MHBEt3 (M = Na, K) to form carbene-borane adducts RC(O)CH2{C(BEt3[NCH2CH2NMes]}. This type of reactivity differs from the previous work on imidazole derivatives. The possible mechanism of these reactions is provided and discussed. The other ligand is p-aryloxy-tethered imidazolinium salt H2LX (L = N-3,5-di-tert-butyl-4-hydrooxyphenyl-N’-mesityl-imidazolinium, X = Cl, Br, PF6 ), which have been synthesised and characterised. The reactions of these salts with MN"(M = Na, K) enabled the characterisation of polymerised complexes of [NaL]n and [KL(thf)2]n. The yttrium complex YL3 is synthesised and its reactivity towards small molecules such as boranes, CO2 and CS2 is discussed. Chapter four presents the primary results on the study of macrocyclic NHC based cyclophane ligand H6LPF6 (L = calix[4]imidazolylidene[2]pyrazolato). Investigations on the reactivity of the ligand towards different bases (NaN", KN", KBn etc.) are examined and subsequent metathesis reactions with RE complexes are explored. Chapter five concludes the work presented in this thesis. Chapter six contains all experimental and characterisation details.

Phosphorus-boron multiple-bonds are of interest because of their predicted reactivity with small molecules; their potential as reagents for the synthesis of molecules isosteric to carbon analogues which exhibit conjugation; and because they have potential as nucleation sites for the solution-phase synthesis of boron phosphide. Phosphaborenes (RP=BR') have not yet been reported due to their propensity to oligomerise to dimers or trimers, even with bulky and electronically-stabilising substituents upon phosphorus and boron. Base-stabilisation at boron allows the isolation of phosphaborenes by preventing oligomerisation, although this alters the reactivity of the phosphaborene unit. An alternative method of studying phosphaborenes free of base or acid coordination is via their thermal generation from a phosphaborene dimer and subsequent in situ reactions with suitable substrates. Chapter 1 examines the potential uses of phosphaborenes in the context of other low-valent main group molecules. The likely reactivity of phosphorus-boron multiple bonds is discussed in the context of the iminoboranes (RNBR') and the isoelectronic heavier group 14 alkyne and alkene analogues. The use of unsaturated main group fragments to build molecular clusters is considered along with the potential role that phosphorus boron multiple bonds could play in preparing boron phosphide fragments. The uses and methods of preparation of group 13/15 containing molecules exhibiting conjugation are discussed, along with the possibility that phosphaborenes would be useful reagents to prepare new P-B/C-C isosteres. Chapter 2 looks at how base-promoted trimethylsilylchloride elimination can be used to prepare base-stabilised phosphaborenes from suitable precursors (RP(SiMe₃)B(X)R' and the mechanism of these reactions. The reactivity of base-stabilised phosphaborenes with Lewis acids is also examined. Chapter 3 covers how base-promoted (L = base) trimethylsilyl halide abstraction from functionalised precursors ((Me₃Si)₃P·BBr₃) can be harnessed to prepare new functionalised phosphinoboranes ((Me₃Si)₂PB(L)Br₂) and phosphaborenes (Me₃SiP=B(L)Br). A 1-dihydro-2-dibromo functionalised phosphinoborane H₂PB(Br₂)L can be prepared from Me₃Si)₂PB(Br₂)L. A subsequent base-promoted dehydrohalogenation yields the hydro-bromo substituted phosphaborene HP=B(L)Br. Chapter 4 examines the in situ thermal generation of a phosphaborene generated from a phosphaborene dimer and its reactivity with bases and unsaturated organic molecules to prepare 1,2-phosphaboretes and 1,2-phosphaboretanes. Chapter 5 explores the diverse reactivity of the 1,2-phosphaboretes. 1,2- phosphaboretes are capable of FLP-like insertion reactions with an isonitrile and carbon monoxide. They are also ring-opened by the coordination of a Lewis acid or base to phosphorus or boron respectively to give P-B containing butadiene analogues. The reaction of the 1,2-phosphaborete with phenyl acetylene proceeds via an unusual carbon-carbon bond cleavage to generate the first example of a 1,3- phosphaborine benzene analogue, rather than the expected 1,4-phosphaborine.

The existence of numerous phosphorus containing functional groups gives phosphorus chemistry its enormous breadth. The range of functional groups stems from phosphorus’ ability to vary its coordination and valance. Phosphorus containing compounds have shown applications in agriculture, biological systems and chemical warfare. High refractive index polymers are used in lenses, fingerprint recognition and optical coatings. However, often these devices rely on to the materials available. Phosphorus rich polymers have shown promise due to the high level of polarisability. A range of poly(phosphate ester)s and polyphosphonates have been synthesised and their thermal and optical properties tested. Some of the samples prepared boast the highest refractive indices for these types of compounds. Polymers synthesised via a polycondensation mechanism usually possess a high dispersity, one way to introduce control is via a ring opening polymerisation (ROP). Novel aromatic phosphonate monomers have been prepared and attempted to polymerise. Monomer, catalyst and copolymerisation scope for aliphatic phosphonate ROP has also been explored. Organocatalysts are becoming increasingly popular in ring opening polymerisation literature, one of the most popular organocatalysts is triazabicyclodecene (TBD). TBD is a dual activating catalyst as it activates both the initiator and monomer via a basic and acidic moiety respectively. Phosphates also have dual activating substituents. A range of aromatic phosphates have been successfully synthesised with varying electron withdrawing/ donating groups. These catalysts were then screened against the polymerisation of β-butyrolactone and their catalytic activity investigated.

Poly(lactic acid), PLA, is a viable replacement to petroleum derived polymers due to its renewable feedstock, biodegradability and bioassimilability, yet improvements in its physical, thermal and mechanical properties are required before it can fully enter all commodity markets. This thesis investigates olefin cross-metathesis (CM) as a synthetic strategy to modify the properties of PLA. The use of novel lanthanide and actinide catalysts on the microstructure control of PLA are also explored. The Tebbe reagent was used in a new synthetic strategy to produce a novel olefin derivative of lactide (MML). Olefin CM of MML with hex-1-ene was successful but polymerisation pre- and post-CM was unsuccessful due to monomer instability. CM of another olefin derivative of lactide, 3-methylenated lactide (3-ML) was successful with aliphatic alkenes; hex-1-ene to dodec-1-ene. To overcome competing alcoholysis of the functionalised monomers, which prevented polymerisation, hydrogenation was used to remove the olefin entity followed by successful ring-opening polymerisation (ROP) to produce polymers of low glass-transition temperatures (Tg). Post-polymerisation CM on an olefin containing polymer P(β-heptenolactone) P(β-HL), with methyl acrylate and an epoxide, generated functionalised homopolymers with increased Tg’s. Co-polymerisation of lactide with β-HL generated novel gradient-copolymers. Olefin CM with 15 different cross-partners produced functionalised copolymers with different thermal properties. Based on this route a new methodology was created to introduce two unique functionalities into the polymer backbone by manipulation of the olefin reactivities. Finally, in a collaborative project, uranium and cerium catalysts, Me3SiOU(OArP)3 and Me3SiOCe(OArP)3 - designed out-with the group- were tested and compared as ROP catalysts for lactide. Both catalysts were active in living polymerisations of L-lactide and under immortal conditions the activity and rates of the catalysts were switched, accounted for by a change in the coordination sphere due to ligand displacement. ROP of rac-lactide using the uranium analogue produced heterotactic-biased PLA with a Pr = 0.79.

Iron-catalysed carbonyl reduction, nitro reduction, formal hydroamination, and the radical alkenylation of alkyl halides have been developed. A Simple, easy-to-make, air- and moisture-stable iron(III) amine-bis(phenolate) complex catalysed the hydrosilylation of carbonyl compounds efficiently using triethoxysilane as the reducing agent. The reaction tolerated a wide range of substrates to give the corresponding alcohol products in good to excellent yields after hydrolysis of the hydrosilylated products (Scheme A1). Scheme A1. Iron-Catalysed Hydrosilylation of Carbonyl Compounds. The same catalyst was also an active catalyst for the chemoselective reduction of nitro arenes into corresponding amines using triethoxysilane as reducing agent. The method exhibited excellent chemoselectivity as other reducible functional groups such as halogen, ester, nitrile all kept unchanged during the reaction. This catalytic system was then successfully applied to the formal hydroamination of alkene to give substituted amine in synthetic useful yields under mild condition. The reaction is hypothesised to proceed through a radical intermediate (Scheme A2). Scheme A2. Iron-Catalysed Nitro Reduction and Alkene Formal Hydroamination. Finally, FeCl2-catalysed formal Heck cross-coupling has been developed between alkyl halides and styrenes. The reaction tolerated both electron-rich and electron-neutral substrates to give the products in moderate to excellent yields. Initial studies revealed that the reaction also proceeds through a radical intermediate (Scheme A3). Scheme A3. Iron-Catalysed Formal Heck Cross-Coupling of Functionalised Alkyl Halides.

There has been much interest in recent years about the potential of microRNA as a new source of biomarkers for the diagnosis of disease. The delivery of new diagnostic tools based on this potential has been limited by shortcomings in current microRNA detection techniques. This thesis explores the development of a new method of microRNA detection through the incorporation of conductive particles into oligonucleotide-functionalised polymers to form oligonucleotide cross-linked polymer composites. Such composites could provide a simple, rapid, and low-cost means of microRNA detection that could be easily multiplexed, providing a valuable tool for point-of-care medical diagnostics. This work presents oligonucleotide-functionalised carbon/polyacrylamide composites which demonstrate a selective swelling response in the presence of analyte oligonucleotide sequences and for which the electrical conductivity decreases with swelling. The composites were synthesised via UV-initiated free-radical polymerisation of carbon/- monomer mixtures upon custom electrode devices, consisting of interdigitated platinum electrodes fabricated upon a silicon substrate. The optimal cross-linker density and carbon loading concentration were determined as well as the best means of dispersing the carbon particles within the polymer. Various types of carbon particles, with differing sizes and aspect ratios, were compared and their performances as conductive additives for polymer swelling transduction evaluated. The swelling behaviour of these composites was evaluated by analysing images of composite microdroplets as they swell. The electrical characteristics of the composites were determined by measuring either the two-terminal resistance or the complex impedance of composite microdroplets on the electrode devices. Alternating and direct current measurement techniques were compared to determine the best approach for the transduction of composite swelling. The volumetric and electrical responses of oligonucleotide-functionalised carbon/polyacrylamide composites were analysed in solutions of analyte oligonucleotide and non-complementary controls. It has been demonstrated that, using carbon nanopowder composites and a direct current two-terminal resistance measurement, it is possible to differentiate between analyte and control solutions to concentrations as low as 10 nM, with single-base precision, in less than three minutes. However, the inability to detect at concentrations below this value, difficulties in differentiating between different analyte concentrations and thermal instability mean that, in their current form, oligonucleotide cross-linked polymer composites are unsuitable for the detection of circulating microRNA at clinically relevant concentrations. Potential avenues of work to address these challenges are discussed. Also presented are collaborative results for oligonucleotide-responsive polymers functionalised with morpholino nucleic acid analogues, in what is believed to be the first example of such a material. These morpholino-functionalised polymers offer significant advantages, in terms of stability and sensitivity, over their nucleic acid equivalents for bio-responsive polymer applications.

Aluminium salen and aluminium salan complexes are excellent catalysts for the ring-opening polymerisation of lactide. This thesis studied their efficacy in the polymerisation of novel monomers and their ability to build new macrostructures. Aluminium salen and aluminium salan complexes were tested as catalysts for ring-opening polymerisation of common aliphatic monomers where controlled polymer synthesis has not yet been achieved with similar systems. Excellent control over molecular weight and dispersity was achieved for β-caprolactone polymerisation, with high molecular weights accessible. Immortal polymerisation could also be performed with an extremely high level of chain transfer agent (up to 100 equivalents) and the highest monomer turnover (10000 monomer equivalents) with aluminium salen catalysts to date. Addition of functional groups to the monomer was also studied; the effect of steric bulk in polymerisation of methylsubstituted derivatives was significant. Protected alcohol functionalities can also be introduced into easily synthesised homopolymers and copolymers. The first example of synthesising a polyester with aromatic functionality within the polymer backbone via polymerisation of cyclic ester monomers was studied with an aluminium salen catalyst. 2,3-Dihydro-5H-1,4-benzodioxepin-5-one polymerisation was facile and proceeded under mild conditions. The resulting polymer could be depolymerised back to starting monomer with the same aluminium salen catalyst under dilute conditions. Random, AB diblock and ABA triblock copolymers were readily synthesised with L-lactide and β-butyrolactone as comonomers. Block copolymers with β-butyrolactone could also be selectively depolymerised, to give poly(3-hydroxybutyrate) homopolymers. Attempted polymerisation of a range of other aromatic monomers was unsuccessful due to addition of steric bulk, changing orientation of the monomer ester bond or decreasing the ring size. Synthesis of homopolymer and ABA triblock copolymers with L-lactide and alkyl-substituted β-lactones was investigated. Homopolymerisation of all alkyl-substituted β-lactones resulted in well controlled polymer, with rate decreasing as alkyl-substituent length increased. A sequential addition of monomers method with β-butyrolactone, β-valerolactone and β-heptanolactone was employed for copolymer synthesis. Copolymers synthesised from β-butyrolactone and β-valerolactone resulted in tunable glass transition and melting temperatures. Copolymers synthesised from β-heptanolactone resulted in thermoplastic elastomers exhibiting microphase separation, supported by differential scanning calorimetry and small-angle X-ray scattering. Finally, optimisation of in situ generated carbonylation catalysts was studied. Optimisation of literature complexes allowed for synthesis of β-valerolactone, β- heptanolactone, β-tridecalactone, 4-chloro-β-butyrolactone and β-6-heptenolactone on relatively large scales under much easier experimental protocols. Additionally, tuning of ortho-phenylene bridged salen ligand framework gave to structure-activity relationships. Using this optimised catalyst system, 4-chloro-β-butyrolactone and β- 6-heptenolactone were prepared and used in ring opening polymerisation. Well controlled and efficient polymerisation of 4-chloro-β-butyrolactone was easily achieved with aluminium salen and salan catalysts. Homopolymers and block copolymers with poly(ethylene glycol) and β-6-heptenolactone were readily synthesised.

Polymers of Intrinsic Microporosity (PIMs) combine the desirable processability of polymers with a significant degree of microporosity generated from the inefficient packing of their rigid and contorted structures. They are attracting attention for a variety of applications including as membrane materials for gas separations. Over the last 30 years, membranes have become an established technology for separating gases and are likely to play key role in reducing the environmental impact and costs of many industrial processes such as O2 or N2 enrichment from air, natural gas upgrading and hydrogen recovery from ammonia production. This thesis describes the synthesis of a series of novel PIMs, primarily PIM-polyimide structures (PIM-PI) and investigates their potential in such applications. In particular, it focuses on the design and synthesis of solution processable PIMs in order to study how structural differences affect the gas permeability. The first section describes the synthesis of a variety of PIM-PIs using large bulky diamines derived from spirobisindane (SBI) and biphenylfluorene (BPF) structures which are useful monomers for achieving high BET (Brunauer-Emmett- Teller) surface areas (> 650 m2 g-1). The second section describes a whole series PIs based on novel and literature based Tröger’s base (TB) diamine monomers. Most of these exhibited good solubility, excellent thermal stability and intrinsic microporosity, with apparent BET surface areas in the range 450-739 m2 g-1. Notably, a polyimide derived from Me2TB and pyromellitic anhydride demonstrates gas permeability data above the 2008 upper bounds for important gas pairs such as O2/N2, H2/N2 and H2/CH4. The third section aims to enforce rigidity within the polymers further by incorporating differently substituted monomers based on rigid ethanoanthracene (EA) units. This includes the formation of a novel EA-EA based PI with an exceptionally rigid polymeric structure, possessing a BET surface area of 694 m2 g-1. In addition to very high permeability, this polymer demonstrates improved gas selectivity due to its enhanced performance as a molecular sieve, placing it amongst some of the highest performing polymers to date. The final section looks at other ways in which rigidity can be enforced including the formation of TB-polymers and thermally rearranged (TR) polymers and assesses their potential for future investigations.