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Poly(vinyl chloride) is one of the most common polymeric biomaterials currently in use in healthcare devices such as endotracheal (ET) tubes. As is often the case, bacterial colonisation of the PVC surface represents a major issue, contributing to poor patient outcomes, increased hospital stays and, in some cases, death. Bacteria readily colonize such surfaces, forming biofilms highly resistant to antibiotic therapy. A prime example of this is the implication of the ET tube in the development of ventilator-associated pneumonia (VAP). Numerous attempts have been made at reducing the incidence of VAP via pharmacological and non-pharmacological methods; however, improvement of ET tube functionality is increasingly being seen as facile means of lowering this risk. This thesis presents a method for the permanent, covalent attachment of a range of molecules with the potential to limit bacterial adherence and survival on modified surfaces which present the opportunity to reduce the incidence of VAP. Fluorination of PVC surfaces was studied as a means of increasing hydrophobicity of the material and reducing surface energy in order to limit bacterial-polymer interaction, thereby reducing adherence and, ultimately, biofilm formation. Results showed that successful modification of less than a third of the PVC surface significantly reduced bacterial adherence. Immobilisation of hydrogel layers on PVC surfaces was also researched in order to permanently attached drug delivery depots. Data obtained indicated that pHEMA could be co-polymerized onto PVC and remain as a functional hydrogel, capable of delivering antibiotics directly to the site of biofilm formation. Incorporation of light-activated microbicidal molecules (photosensitizers) and quaternary ammonium salts, with a view to future development of similar surface functionalising compounds, revealed that both methods were capable of producing significant reductions in bacterial activity on ET tubes. In particular, photosensitizers offer an on-demand activity which could be utilised if VAP is suspected.

The aim of this research programme was to examine the potential of photosensitiser incorporated copolymers in creating an anti-infective biomaterial for ocular use. A range of copolymers with varying amounts of the monomers HEMA, MAA and MMA were successfully manufactured and impregnated with the cationic porphyrin, TMPyP via a dipping method with exploited the electrostatic interactions between TMPyP and the anionically charged copolymers. It is desirable to surface-localise the TMPyP incorporation as much as possible, so that it may exert its antimicrobial effect at the material surface where required, and may also limit the impact ofTMPyP upon the optical transparency of the copolymer. Increasing the amounts of MMA in the copolymers led to an increase in surface localisation, as shown with confocal microscopy. This subsequently improved the antibacterial activity of the copolymers with optimal efficacy found for the blend containing 10%MAA, 10%MMA and 80% HEMA . Commercially available contact lenses were also impregnated with photosensitisers. Confocal microscopy showed the degree of localisation of the photosensitisers and bacterial adherence testing demonstrated that these lenses were active against gram-positive ocular pathogens, showing that an anti-infective contact lens was successfully made. Solutions of photosensitisers were tested against various bacterial pathogens, both alone and in combination with other antibacterial agents such that synergistic activity could be assessed. It was demonstrated that TMPyP is an effective antibacterial agent when used alone. However, it was further shown that the combinations of TMPyP with polymyxin B and also with chlorhexidine displayed synergistic properties. The concentration of TMPyP required to bring about bacterial kill was significantly reduced in the presence of polymyxin B/chlorhexidine whilst also reducing the time required for bacterial disinfection. The use of such solutions could have potential for the development of novel MPS.

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This thesis details the synthesis of fluorescent and redox active compounds for their incorporation into metal-organic coordination polymers. In particular, we report the synthesis of ligands bearing flexible imidazolate and/or carboxylate donors, their reaction with first row transition metal ions and the structural properties of the resulting materials. Chapter 1 introduces the properties, synthesis and applications of metal-organic coordination polymers, in particular crystalline three -dimensional (3~) frameworks, with reference to notable successes within the field. Chapter 2 details the synthesis of five metal-organic coordination polymers based on a novel 2,5-bis(3-(1-imidazolyl)propylcarbamoyl)terephthalate ligand and Zn2+, C02+, Mn2+ and Cu 2+ cations. The coordination environments and structural connectivities within each are compared, with particular attention paid to a rare example of Mn2+ -based supramolecular tological isomers. In Chapter 3 we investigate the use of a N,N'-bis(3-(1 -imidazolyl)propyl)-l,4,5,8- naphthalene-tetracarboxylicdiimide ligand for the formation of nano-scale metalorganic coordination polymers (NCPs). In particular, we examine the effect of both nature of metal ion and starting material concentration on particle size and morphology. Synthesis of comparable crystalline macro-scale materials and subsequent spectroscopic studies allow us to draw conclusions on the effect of metal ion on polymer dimensionality and NCP morphology: whilst two-dimensional (20) Mn(II) -based coordination sheets adopt a nano-rod morphology, onedimensional (10) Cu(II)-based chains form nano-spheres. Chapter 4 details the synthesis of porphyrin ligands bearing flexible imidazolate or carboxylate donors. We report both 10 and 20 coordination polymers based on a 5,15-dimesityl- 10,20-bis(4-phenylacetate)porphyrin ligand and Mn2+ ions, and iii both networks are unusual in that they comprise free base porphyrins and hydrogen bond with encapsulated uncoordinated ligand to afford 2D and 3D frameworks respectively. In Chapter 5 we report a series of borondipyrrin (BODIPY) compounds and investigate the effect of functional and positional substitutions on the electrochemical and optical properties of these chromophores. We further characterise the optical properties of electrochemically generated BODIPY anions and cations and examine the locations of the unpaired electrons of these species via density functional theory calculations and electron paramagnetic resonance spectroscopy. The series of compounds extends into the first examples of BODIPY dimers connected via their boron centres and we detail efforts to incorporate these species into metal-organic coordination polymers. iv

Thermosetting resins undergo irreversible polymerization to form a 3 Dimensional Structure (3D) via a cure reaction. For the present research, properties of thermosetting resins are studied by analysing cure kinetic modelling as well as investigating various additives and fillers to enhance thermal and mechanical propelties for the modified resin composition. Different ratios of Diglycidyl Ether of Bis-Phenol A (DGEBA) are used with aliphatic amidoamine hardener to study the effects of increasing resin content on an epoxy resin/hardener sample. Epoxy/Hardener samples with ratio 2: 1, 3: I and 4: I were studied to investigate the effect of increasing epoxy content on cure and mechanical properties. Analysis using Dynamic Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA) and cure modelling was used to explain the thermal characterization and tests involving tensile, flexural, Scanning Electron Microscopy (SEM) and hardness explain the mechanical property changes when mixing ratio is varied. DSC and TGA results showed the presence of two peaks especially at higher heating rates of non-stoichiometric ratios. Cure kinetic modelling using autocatalytic equation of Cure Rate (du/dt) predicted the bell shaped curve and estimated cure kinetic constants irrespective of the mixing ratio. ABSTRACT Mechanical and thermal property analysis of samples showed that increasing ratio drives brittle behavior for the DGEBA/Hardener samples. The autocatalytic model is also used for investigating thermal behavior of two part epoxy-adhesive sample. Dynamic scans for adhesive were conducted at heating rates of 5, 10 and 15 QC for a temperature ranging from room temperature to 200 QC. The autocatalytic equation still predicted the bell-shaped curve uSll1g cure kinetic constant determined by Borchard and Daniels method. Chitosan a polysaccharide component which is normally found on exoskeleton of shrimps and crabs was added to epoxy resin to alter the chemical :1 and mechanical properties. Here DGEBA was also used as the primary epoxy base with hardener Hexamethylenediamine (HMDA) to create epoxy/hardener blends with different weight percentage of chitosan. Agglomeration at higher loadings of chitosan was confirmed by morphological analysis and this agglomeration inturn compromised the mechanical properties due to the miscibility of chitosan filler in epoxy. There is a considerable change to thermal stability on adding chitosan. This thesis presents new data on the validity of the analytical curing models to determine thermal and mechanical behaviour of epoxy based resins and adhesives. In addition data on chitosan loaded epoxy shows for the first time achievable levels of filler loadings and consequential thermal and mechanical properties.

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