In the last decade, block copolymers have attracted growing interest because of their ability to form a wide range of nanostructures through self assembly. These nanostructures could be designed to have miscellaneous properties, such as high stability, biocompatibility, functionality, capacity of carrying a variety of molecules and versatile architectures. Block copolymers can be prepared as hybrid systems with many diverse compounds including biomolecules. Moreover, they can be environment responsive, and release of components within the polymer can be controlled by stimuli. Due to these properties, block copolymers are finding applications in several areas including drug delivery, biotechnology and diagnostics. In this thesis it was aimed to characterise a variety of novel block copolymer assemblies in order to have a better understanding about the properties of these materials for potential applications in pharmaceutical SCIences. Assemblies including the block co-polymers of synthetic materials, the block co-polymers of synthetic materials and proteins, and the block co-polymers of synthetic materials and nucleic acids were characterised by AFM, and additionally by TEM, DLS, fluorescence spectrometry and zeta potential measurements. The morphologies and self-assembly mechanisms of the structures were investigated by altering the conditions (i.e. temperature, pH and buffer strength), and the real-time responses were recorded in order to be able to VI Abstract predict in vitro and in vivo behaviours of these systems. Also the effects of additional substances (i.e. biomolecules and reducing agents) to assembly/disassembly paths of the materials were inspected. The results of this project provide some useful and new insights about the behaviour of a range of block copolymer materials such as self-assembly properties of the synthetic block copolymer structures and the stability of these assemblies at various pH values, dynamic nature of protein-polymer conjugates across temperature changes, and response mechanisms of DNA-polymer conjugates across a number of stimuli (i.e. binding / hybridisation / strand breaking stimulus) which influence the assembly/disassembly paths of the materials. This information leads to better understanding of their potential applications as drug delivery systems, advanced responsive therapeutics, and diagnostics, and also designing better systems in future studies. VB

Carbon nanotubes and nanofibres offer the potential for enhancement of a range of polymer properties. A number of types of fillers are available, ranging from single (SWNT) and multi-walled (MWNT) carbon nanotubes, with large aspect ratios (>1000) and longitudinal moduli approaching a terapascal, to more readily available vapour-grown carbon nanofibres (CNF), with longitudinal moduli of around 240GFfl.

Previously functional plasma polymers have been demonstrated to act as protective films for reinforcing fibres and provide adhesion to matrix resins in the formation of composite. In this work, the model interphase surface from the allylamine (AAm)1 1,7-octadiene (Oct) plasma copolymer treated with DGEBA-Br epoxy was produced in order to simulate the formation of an interphase region under differing cure regimes. The fundamental interaction of epoxy with a plasma polymer coating deposited onto an electrical grade (E-glass) substrate was investigated to understand the nature of interpenetrating network. X-ray photoelectron spectroscopy (XPS) was utilised to quantify the surface chemistry of the deposited coating and the model interphase surfaces. With a complementary of ARXPS, the penetration of epoxy into the plasma polymer coating was examined. It was found that the ratio of C-N/C increased in all model interphase surfaces in comparison to control AAm plasma copolymer. This confirmed that the chemical reaction between amine functional groups of the plasma polymer and epoxide groups of the epoxy had occurred through the formation of cross-links to form a semi-interpenetrating network (IPN). It therefore resulted in the presence of interphase region in which the AAm plasma copolymer and the epoxy formed the IPN. It was also observed that the interphase was principally formed at the outermost surface. However at a higher post-heat treatment temperature (80°C 2hl 120°C 3hl ISO °c 4h) the chemical bond was found to create through all analysis depth, thus enabling a thicker interphase to be formed. Time of flight secondary ion mass spectrometry (ToF-SIMS) images from the fracture surfaces of model surfaces were used to establish the mode of failure as well as uniformity of the epoxy overlayer. It was demonstrated that the locus of failure occurred at the interface between the AAm plasma copolymer coating and the E-glass substrate. This can confirm a strong interfacial bond between the coating and the epoxy.

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A number of polyurethane (PU) I poly(ethyl methacrylate) (PEMA) interpenetrating polymer network nanocomposites were investigated with regard to morphology and energy absorbing ability. The nanoclays used were umnodified sodium montmorillonite clay and three different types of organically-modified clays: C15A, C20A and C30B. The nanoclays were incorporated into the IPNs by using an in-situ polymerisation method. The clay dispersions were characterised by wide angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM). The morphologies of the IPNs were determined with dynamic mechanical thermal analysis (DMTA), TEM and modulated-temperature differential scanning calorimetry (M-TDSC), while the mechanical properties were investigated using tensile testing and hardness measurements. Firstly, the original synthesis procedure and formulation was adjusted by varying the nanoclay C20A content, IPN composition ratio, nanoclay mixing time and PU catalyst, including a study of the PU and PEMA homopolymer composites. All IPN composites showed only partially intercalated nanocomposites as revealed by WAXD and TEM results. 70PU/30PEMA (70:30 composition ratio) IPN nanocomposites exhibited potential as materials for damping applications as it had a broad loss factor ≥ 0.3 spanning a wide temperature range. Secondly, the synthesis procedure was modified by changing the order of nanoclay mixing with homopolymer components. All lPN composites were based on a composition ratio of 70PU/30PEMA, 5 wt% C20A content, 1.2 wt% of PU catalyst and 30 min mixing time. High intensity ultrasonic waves were also introduced in the nanoclay mixing step for one hour. However, the ultrasonication showed only a marginal change in damping properties. Finally, a number of other nanoclays were incorporated into the 70PU/30PEMA IPN. All IPN composites achieved only a partial intercalation, except for the C30B-filled lPN where no changes were revealed by W AXD. All nanoclays caused a decrease in the glass transition of both homopolymers. IPN nanocomposites tended to reveal a higher extent of phase separation with increased clay content, but only the Na clay-filled lPN still showed a broad loss factor value, even at higher clay content. Improved modulus of elasticity was shown by all nanoclays, with increased clay loading. Whereas a moderate increase in the tensile strength was only shown at 1 wt% clay content.

Polymer pipe materials being widely used in the industry for transport purposes introduced new areas of research from mechanics of materials perspective. In this study the effect of structural parameters on the fracture resistance of polyethylene pipe material have been investigated via testing materials differing in their overall structure, density, crystallinity, molecular weight, and carbon black by performing S4 tests in addition to Instrumented Charpy, Reversed Charpy and Tensile Tests. Furthermore, the effect of extrusion conditions have been investigated via performing S4 Tests on pipes having differing process histories. A new technique of analysing tensile testing enlightening plane stress resistance is demonstrated. The stability of adiabatic drawing in a tensile test is found to be related to the plane stress fracture resistance, which forms the basis of the RCP resistance of a pipe. This proposed method enables the use of two basic material properties – yield stress and strain hardening modulus – for ranking of the pipes RCP performances, making the idea of tailor-made pipes possible.

The present research work has studied the fatigue behaviour of matrices and fibre-composites based upon modified epoxy polymers. The basic epoxy polymer has been modified with (a) nano-silica particles, (b) micrometre-rubber particles, and (c) both of these additives, to give a ‘hybrid’ modified epoxy. These modifications have been undertaken in order to try to increase the cyclic fatigue resistance of the fibre-composite material. The experimental work has used a linear elastic fracture mechanics (LEFM) approach to firstly ascertain the fatigue properties of the epoxy polymer matrices. Secondly, the unmodified (i.e. control) and the modified epoxy resins were used to fabricate glass fibre reinforced plastic (GFRP) composite laminates by a resin infusion under flexible tooling (RIFT) manufacturing method. Tensile cyclic fatigue tests were performed on these composites, during which the degree of matrix cracking and stiffness degradation were also monitored. The fatigue life of the GFRP composite was significantly increased due to the presence of the nano-silica particles and/or micro-rubber particles. Suppressed matrix cracking and a reduced crack propagation rate in the modified matrix of the fibre-composite were observed to contribute towards the enhanced fatigue life of the composites containing the nano-silica particles and/or micro-rubber particles. The theoretical studies employed an extended finite element method, coupled with a cohesive zone model, to predict the fatigue behaviour of the fibre composites based upon the unmodified (i.e. control) and modified epoxy polymer matrices. A ‘user element subroutine’ has been developed in Abaqus to incorporate the extended finite element method and a mathematical model has been proposed to evaluate the constitutive laws for the cohesive zone model to simulate the growth of fatigue cracks. A fatigue degradation strategy based on the ‘Paris law’ (determined from the fatigue tests on the matrix materials) has been adopted to change the constitutive law for the cohesive zone model as a function of the number of fatigue cycles that have been accumulated. The theoretical predictions for the fatigue behaviour have been compared to the experimental results, and very good agreement between the theoretical and experimental results was found to exist.

Composites of poly methylmethacrylate containing quartz particles and glass beads have been prepared over a range of filler contents. Organosilicon compounds (silanes) have been employed as bonding agents between filler and matrix. To study the reactions between silane and filler, model experiments have been performed on fumed silica surfaces using infra red spectroscopy. Modulus, flexural strength and compressive strength of composites have been determined as a function of volume fraction of filler.

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