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This research aimed to develop new polymeric materials for use in membrane or adsorption processes for carbon dioxide capture. In particular, it explored the synthesis, characterization and properties of polymers incorporating a spiro-center. A dianhydride containing a spiro-center (An-1), suitable for use in the preparation of polyimides, was synthesized using a previously reported procedure. The spiro-center makes the structure of the resulting polymers (PIM-PIs) similar to polymers of intrinsic microporosity (PIMs), which are known for their high internal surface area and outstanding membrane permeation properties. PIM-polyimides PIM-PI-1 and PIM-PI-5 were successfully synthesized and characterized, and membranes prepared for permeation studies. For PIM-PI-5, gas permeation data were obtained for the first time and were shown to be in reasonable agreement with values predicted by a group contribution method. To produce membranes with even better gas permeation properties, hydroxyl-containing PIM-polyimides were introduced. The presence of a hydroxyl group in the ortho position of the imide linkage made it possible to thermally rearrange the PIM-polyimide to a PIM-polybenzoxazole (PIM-PBO) at 450 oC in an inert atmosphere. PIM-PI-OH-1 with high enough molecular weight to form a freestanding membrane was successfully synthesized using two different synthetic methods: thermal imidization and one-step polycondensation. The PIM-PI-OH-1 polymers prepared by both synthetic methods were compared in terms of gas permeation properties and CO2 uptake capacity, before and after thermal rearrangement. As expected, for polymers prepared by both methods, a significant enhancement was observed in the membranes gas permeation properties upon thermal rearrangement. Ethanol treatment was also performed on the thermally rearranged polymers, which resulted in a large increase in their permeability. The effect of aging was investigated on the ethanol treated PIM-PBO-1 membranes. It was observed that the membranes gradually lose the extra permeability created upon ethanol treatment and return to close to their original permeability value. To increase the concentration of thermally rearrangeable sites in the polymers, a dianhydride (An-2) with a smaller structure and lower molecular weight comparing to the An-1 was synthesized. A copolymer (copolymer-OH(1-2)), was synthesized using An-1 and An-2 (1:1). Gas permeation measurements were performed on the thermally rearranged polymer before and after ethanol treatment. A slight enhancement in the polymer’s selectivity toward CO2/N2 and CO2/CH4 gas pairs was observed, while maintaining the permeability. Having the same aim, PIM-PI-OH-3 was prepared using a smaller and a more rigid diamine, compared to the diamine used in the preparation of PIM-PI-OH-1. Gas permeation studies of the thermally rearranged membrane before and after ethanol treatment showed a significant increase in O2/N2 selectivity, which passed the Robeson 2008 upper bound. In adsorption experiments, CO2 uptake was higher than for PIM-PI-OH-1 and its thermally rearranged product.

Im Rahmen dieser Arbeit wurden neuartige, temperatursensitive Polymerbürsten mit terminaler Click-Funktionalität hergestellt, die nicht nur im Detail untersucht bzw. charakterisiert wurden, sondern deren Eigenschaften zusätzlich durch die polymeranaloge Umsetzung mit einem entsprechend modifizierten Fluoreszenzfarbstoff, Polymer oder mit superparamagnetischen Nanopartikeln erweitert werden konnten. Mittels kontrolliert radikalischer Polymerisation wurde mono- und bi-funktionalisiertes Poly(N-isopropylacrylamid) mit unterschiedlichen Endgruppen und Molekulargewichten synthetisiert und über das "grafting to"-Verfahren an eine Modeloberfläche angebunden. Die kovalente Anbindung der entsprechenden Komponenten erfolgte entweder durch die Kupfer-katalysierte oder thermisch induzierte Alkin-Azid-Cycloaddition. Neben den physiko-chemischen Eigenschaften wurde im Besonderen das temperaturabhängige Schaltverhalten dieser funktionellen Polymerbürsten in situ untersucht, wobei neben der spektroskopischen Ellipsometrie als Hauptmethode, zusätzlich Rasterkraftmikroskopie, UV/VIS- und Fluoreszenzspektroskopie, sowie Elektronenmikroskopie verwendet wurden. Im Fall der Farbstoff-modifizierten Polymerbürsten zeigte sich, dass nicht nur die Eigenschaften des Farbstoffs durch das Polymer beeinflussbar sind, sondern auch das Quellverhalten der Polymerbürsten durch den Farbstoff. Die mit Nanopartikeln modifizierten Polymerbürsten zeigten eine homogene Verteilung der Partikel auf der Oberfläche, sowie eine veränderte Schaltcharakteristik, die durch das Auftreten eine dynamischen Wechselwirkungszone zwischen den Polymerbürsten und den Nanopartikeln erklärt werden kann. Mit Hilfe der thermisch induzierten Azid-Alkin-Cycloaddition konnten erstmalig definierte Kettenverlängerungen an Polymerbürsten durchgeführt und gleichzeitig der Nachteil der limitierten Pfropfungsdichte der „grafting to“-Methode überwunden werden. Darüber hinaus konnte der temperaturinduzierte Schalteffekt nicht nur erhalten bleiben, sondern in Bezug auf die Schaltamplitude auch signifikant vergrößert werden und ergab ein sensitiveres, verbessertes Polymerbürstensystem.

The present thesis work deals with the development of a novel manufacturing protocol for the realization of excimer laser micro-patterned freestanding hydrogel layers (50 to 300 ??m thickness) based on thermo-responsive poly-(N-isopropyl)acrylamide (PNIPAAm) which can operate as temperature-triggered actuators for cells-on-chip applications. PNIPAAm based thin films were synthesized in house and manufactured by an injection/compression moulding based technique in order to obtain flat hydrogels attached to rigid polyvinyl chloride (PVC) substrates to facilitate laser focusing. Laser machining parameters were empirically optimized to fabricate arrays of through-holes with entrance diameter ranging from 30 ??m to 150 ??m and having different exit diameter (from 10 to 20 ??m) on the PNIPAAm employing a stencil aluminum mask. After laser processing, the microstructured layers were detached from the PVC using a chemical treatment and then left to swoll in pure water. The KrF excimer laser machined through-holes could be reversibly modulated in terms of size as a consequence of the polymer volumetric phase transition induced by a temperature change above the critical value of 32 ??C. Thermo-responsiveness characterization was carried out on the detached water swollen freestanding layers using a thermostat bath, by changing the temperature from 18 ??C to 39 ??C and each sample could undergo multiple cycles. As a result of the polymer water loss, the shrinkage of the layer caused the holes to shrink homogeneously, thus reducing their original size of about the 50% in the polymer collapsed state. To prove the functionality of these stimuli-responsive smart surfaces in the frame of cells-on-chip systems, they were integrated in a multilayer microfluidic device to operate as self-regulating cell sorting actuators for single cell assays applications. Using mechanical fastening as the packaging strategy, the hydrated hydrogel was sealed between two micro-milled poly-methyl methacrylate (PMMA) components, which provided the fluid accesses and ducts to the cell suspension to be flown over the thermoresponsive actuator (top layer) and the well to collect the sorted sample (bottom layer). The device is also equipped with a thin transparent heater to control the microfluidic chip temperature. When the system is assembled, the temperature-triggered actuation mechanism was exploited to trap a cellular sample in the shrunken exit hole on the top of the hydrogel layer by applying a negative pressure across the film via the bottom PMMA component when the system is kept at 37 ??C. Subsequently, the sorting of the trapped cell took place through the micro-capillary when the polymer natural relaxation at room temperature towards its initial state occurred; the operational principle of the device was proved using MG63 cells as a model cell line by monitoring the sorting through the size-modulating structures using optical microscopy.

Microfluidic systems are being used in more and more areas and the demand for such systems is growing every day. To meet such high volume market needs, a cheap and rapid method for sealing these microfluidic platforms which is viable for mass manufacture is highly desirable. In this work low frequency induction heating (LFIH) is introduced as the potential basis of a cost-effective, rapid production method for polymer microfluidic device sealing. Thin metal layers or structured metal features are introduced between the device s substrates and heated inductively. The surrounding material melts and forms a bond when cooling. During the bonding process it is important to effectively manage the heat dissipation to prevent distortion of the microfluidic platform. The size of the heat affected zone (HAZ), and the area melted, must be controlled to avoid blockage of the microfluidic channels or altering the channels wall characteristics. The effects of susceptor shape and area, bonding pressure, heating time, etc, on the heating rate have been investigated to provide a basis for process optimisation and design rules. It was found that the maximum temperature is proportional to the square of the susceptor area and that round shaped susceptors heat most efficiently. As a result of the investigations higher bonding pressure was identified as increasing bond strength and allowing the reduction of heating time and thus the reduction of melt zone width. The use of heating pulses instead of continuous heating also reduced the dimensions of melt zones while maintaining good bond strength. The size of the HAZ was found to be negligible. An analytical model, which can be used to predict the heating rate, was derived. In validating the model by numeric models and experiments it was found that it cannot be used to calculate exact temperatures but it does correctly describe the effect of different heating parameters. Over the temperature range needed to bond polymer substrates, cooling effects were found not to have a significant impact on the heating rate. The two susceptor concepts using thin metal layers (metal-plastic bonds) or structured metal features (plastic-plastic bonds) were tested and compared. While the metal-plastic bonds turned out to be too weak to be useful, the bonds formed using structured susceptors showed good strength and high leakage pressure. Based on the knowledge gained during the investigations a microfluidic device was designed. Different samples were manufactured and tested. During the tests minor leaks were observed but it was found that this was mainly due to debris which occurred during laser machining of the channels. It was concluded that induction bonding can be used to seal plastic microfluidic devices. The following guidelines can be drawn up for the design of susceptors and process optimisation: Materials with low resistivity perform better; For very thin susceptors the effect of permeability on the heating rate is negligible; The cross-sectional area of the susceptor should be as large as possible to reduce resistance; The thickness of the susceptor should be of similar dimensions to the penetration depth or smaller to increase homogeneity of heat dissipation; The shape of the susceptor should follow the shape of the inductor coil, or vice-versa, to increase homogeneity of heat dissipation; The susceptor should form a closed circuit; Higher bonding pressure leads to stronger bonds and allows reduced heating times; Pulsed heating performs better than continuous heating in terms of limited melt area and good bond strength. The drawbacks of the technique are explained as well: introducing additional materials leads to additional process steps. Also the structuring and placement of the susceptor was identified to be problematic. In this project the structured susceptor was placed manually but that is not feasible for mass manufacture. To be able to use the technique efficiently a concept of manufacturing the susceptor has to be found to allow precise alignment of complex designs.

Inkjet printing (jetting) technology, due to its high speed of operation and accuracy, is utilised in Additive Manufacturing (AM) of three dimensional parts. Commercially available AM processes that use jetting technology include three dimensional printing (3DP by Z-Corporation), Polyjet (by Objet), Multi Jet Modelling (MJM by 3D Systems) and three dimensional printing by Solidscape. Apart from 3D Printing by Z-corporation, all the other jetting based processes require a support material to successfully build a part. The support material provides a base to facilitate the removal of the part from the build platform and it helps manufacturing of cavities, holes and overhanging features. These support materials present challenges in terms of their removability and reusability. This research is therefore, aimed towards finding a support material composition that can be used with jetting based AM processes. The support material should be easily removable either by melting or by dissolution and also, if possible, it should be reusable. AM processes often process materials with poor mechanical properties and therefore, the parts produced by these processes have limited functionality. In an attempt to obtain complex shaped, functional parts made of nylon (i.e. Polyamide 6), a new jetting based AM process is under research at Loughborough University. The process uses two different mixtures of caprolactam (i.e. the monomer used to produce polyamide). These mixtures are to be jetted using inkjet heads and subsequently polymerised into polyamide 6. Therefore, another aim of this research was to consider the support material s suitability for jetting of caprolactam. Two different polymers were researched which included Pluronic F-127 and methylcellulose (MC). Both these polymers are known for gel formation upon heating in aqueous solutions. Due to the inhibition of polymerisation of polyamide 6 by the presence of water, non-aqueous solvents such as ethylene glycol, propylene glycol and butylene glycol were studied. Since both F-127 and MC in the glycols mentioned above had not been studied before, all the compositions prepared and investigated in this report were novel. F-127 did not show gel formation in propylene and butylene glycol but formed a gel in ethylene glycol at a concentration of 25% (w/w) F-127. MC, on the other hand, showed gel formation upon cooling in all the three glycols at concentrations as low as 5% for ethylene glycol and 1% for both propylene and butylene glycol. These compositions were characterized using experimental techniques such as Fourier Transform Infrared (FTIR) spectroscopy, hot stage microscopy, differential scanning calorimetry (DSC) and X-ray diffraction (XRD). A mechanism of gelation for both F-127 and MC in glycols is presented based on the results of these characterisation techniques. Viscosity and surface tension measurements along with the texture analysis of selected compositions were also performed to evaluate their suitability for jetting. All these compositions, due to their water solubility and/or low melting temperatures (i.e. near 500C) present the advantage of ease of removal. Removal by melting at low temperatures can also provide reusability of these support materials and thus advantages such as reduction in build cost and environmental effect can be achieved.

The main aim of this project was to investigate the possibility of manufacturing 3D parts of polyamide (nylon or PA) 6 by inkjetting its monomer caprolactam (CL). The principle of this process was similar to the other rapid prototype (RP) and rapid manufacturing (RM) processes in which a 3D part is manufactured by layer on layer deposition of material. PA6 was used as the thermoplastic polymer in this work because of its good properties and also because PA6 can be produced by heating its monomer (i.e. plus catalyst and activator) in a short time. Two polymerisation mixtures of CL-catalyst (mixture A) and CL-activator (mixture B) are intended to be jetted separately using conventional jetting heads and polymerise shortly after heating. Anionic polymerisation of CL (APCL) was investigated in the bulk and on a smaller scale. Sodium caprolactamate (CLNa and C10) and caprolactam magnesium bromide (CLMgBr) were used as catalysts and N-acetylcaprolactam (ACL) and a di-functional activator (C20) were used as activators. The influence of polymerisation conditions was investigated and optimised. These were catalyst-activator concentration, polymerisation temperature and the influence of the polymerisation atmosphere. The physical properties (monomer conversion, crystallinity, and viscosity average molecular weight) of PA6 samples produced using each catalyst-activator combinations were measured and compared. Small scale polymerisation was carried out using a hotplate, by hot stage microscopy and using differential scanning calorimetry (DSC). The influence of heating strategy on small scale polymerisation was studied using DSC. The polymerisation mixture compositions were characterised using rheometry, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and optical microscopy to investigate their suitability in jetting for using the available jetting heads. It was shown that the combination of CLMgBr-ACL resulted in fast polymerisation which was not sensitive to moisture. The C10-C20 combination resulted in fast polymerisation with the best properties in a protected environment (nitrogen); however, the polymerisation was affected by moisture in air and the properties of polymer produced and rate of polymerisation decreased in air. Polymers produced using CLNa-ACL had the poorest properties and polymerisation did not occur in air. Material characterisation showed that micro-crystals of CLMgBr existed in CLMgBr-CL mixture at the jetting temperature (80oC) which were too large to be jetted. However, the mixture of C10 in CL could be partially jetted. The activator mixtures had similar properties to CL and were easily jetted. Drop on drop polymerisation was carried out by dripping droplets of mixtures A and B (at 80oC) on top of each other on a hotplate at the polymerisation temperature. Small scale polymerisation in a DSC showed that the monomer conversion increased with increase in polymerisation temperature from 140oC to 180oC and decreased from 180oC to 200oC. The crystallinity of the polymer produced in the DSC decreased with increase in polymerisation temperature. Hot stage microscopy produced evidence for simultaneous polymerisation and crystallisation processes on heating. Small scale polymerisation in an oven and analysed by DSC showed that increasing catalystactivator concentration resulted in increasing monomer conversion and decrease in crystallinity. Monomer conversion also increased with increase in polymerisation temperature and polymerisation time. Comparison between small scale and bulk polymerisations shows a good agreement between the two polymerisation rates. This shows that the polymerisation mechanism did not change significantly when the quantity of materials was reduced to less than 20mg. Finally, the polymerisation was carried out in a DSC after jetting C10-CL and C20-CL mixtures into a DSC pan using a jetting system, which was made in another work.

Plusieurs mécanismes de polymérisation radicalaire contrôlée (PRC) sous irradiation lumineuse ont récemment été développés. Ces approches offrent potentiellement de nombreux avantages, en permettant notamment d’introduire dans le mécanisme des PRCs certaines caractéristiques propres aux photopolymérisations, tels que les contrôles spatial et temporel de la réaction. Les travaux de thèse présentés dans ce manuscrit s’inscrivent dans ce contexte, en ayant pour objectif le développement et l’étude d’un nouveau mécanisme de polymérisation radicalaire par transfert d’atome (ATRP) photocatalysée. Après une étude bibliographique présentant l’état de l’art dans le domaine des PRCs sous irradiation lumineuse (chapitre 1), un complexe de bis(1,10-phenanthroline) cuivre (I) (Cu(I)) est utilisé comme catalyseur pour la synthèse de poly(méthacrylate de méthyle)s bien définis par ATRP menée sous l’irradiation d’une lampe LED bleue de faible intensité (chapitre 2). Le mécanisme proposé implique la formation de l’état excité Cu(I)* à partir de Cu(I) sous irradiation, suivie de sa désactivation oxydative par les composés bromés, générant les espèces actives propagatrices et la forme désactivante du complexe Cu(II). Le cycle catalytique est ensuite complété par l’ajout de triethylamine comme agent réducteur permettant la régénération in situ de la forme activante Cu(I) du complexe et conduisant ainsi à une polymérisation plus rapide. Le méthacrylate de glycidyle est ensuite considéré comme comonomère jouant simultanément le rôle d’un agent réducteur (chapitre 3). Des copolymères fonctionnels bien définis, avec une distribution contrôlée de groupes latéraux époxydes, sont ainsi synthétisés. Enfin, le mécanisme d’ATRP photocatalysé est amélioré en développant une procédure permettant la génération in situ de la forme activante Cu(I) en partant d’un complexe Cu(II) stable en présence d’air (chapitre 4). Le mécanisme ainsi développé présente une bonne tolérance à la présence d’oxygène ou d’inhibiteur dans le milieu réactionnel. Les effets de plusieurs paramètres (intensité lumineuse, concentration en ligand et nature du solvant ou du contre-ion) sont étudiés, suggérant un échange de ligand photo-induit comme processus photochimique additionnel impliqué dans le mécanisme d’ATRP photocatalysé étudié. / Several mechanisms of controlled radical polymerization (CRP) under light irradiation have been recently developed. These approaches offer potentially numerous advantages, enabling especially to introduce in the mechanism of CRPs some features characteristic of photopolymerizations, such as the spatial and temporal controls of the reaction. The PhD work presented in this manuscript comes in this framework, aiming at developing and studying a new mechanism of photocatalyzed atom transfer radical polymerization (ATRP). After a bibliographic study presenting the state-of-the-art in the domain of CRPs under light irradiation (chapter 1), a bis(1,10-phenanthroline) copper (I) complex (Cu(I)) is used as catalyst for the synthesis of well-defined poly(methyl methacrylate)s by ATRP carried out under the irradiation of a low intensity blue LED lamp (chapter 2). The proposed mechanism implies the formation of the excited state Cu(I)* from Cu(I) under irradiation, followed by its oxidative quenching by the brominated compounds, generating the growing active species and the deactivator form of the complex Cu(II). The catalytic cycle is then completed by the addition of triethylamine as a reducing agent enabling the in situ regeneration of the activator form of the complex Cu(I), therefore leading to a faster polymerization. Glycidyl methacrylate is then considered as a comonomer playing simultaneously the role of a reducing agent (chapter 3). Well-defined functional copolymers, with a controlled distribution of epoxide side groups, are thus synthesized. Finally, the photocatalyzed ATRP mechanism is improved by developing a procedure permitting the in situ generation of the activator Cu(I) starting directly from an air-stable Cu(II) complex (chapter 4). The mechanism developed in this way exhibits a good tolerance to the presence of oxygen or inhibitor in the reaction medium. The effects of several parameters (light intensity, ligand concentration and nature of the solvent or counter-ion) are studied, suggesting a photo-induced ligand-exchange as an additional photochemical process implied in the studied photocatalyzed ATRP mechanism.

This thesis focuses on improved processing methods for enhanced mechanical properties in polymer nanocomposites, and controlled drug release in polymer based delivery systems. Supercritical carbon dioxide assisted mixing was successfully used in preparation of polypropylene/sepiolite and polypropylene/multiwall carbon nanotube nanocomposites. Relatively homogeneous dispersed and well separated nanofillers were obtained throughout the PP matrix. A better preservation of nanofiller lengths was observed in the scCO 2 assisted mixing. Mechanical property studies showed a marked increase in Young's modulus and tensile strength with the addition of nanofillers. More interestingly, techniques usually designed to achieve high quality PP nanocomposites, such as the use of masterbatches, maleic anhydride grafted polypropylene compatibilizers or polymer coated MWNTs are not needed to achieve equivalent mechanical properties with scCO2 assisted mixing. ScCO2 was also used as a foaming technique to modify the traditional cured poly(ethyl methacrylate/tetrahydrofurfuryl methacrylate) system for a controlled release of chlorhexidine. Highly porous structures were produced and chlorhexidine released from scCO2 foamed samples was more than 3 times higher than traditionally cured samples. By altering the processing conditions, such as CO2 saturation time and depressurization time the CX release rate was altered. Finally, the electrospinning method was combined with the layering encapsulation technique in order to enable the incorporation of water-soluble drugs in poly(lactic-co-glycolic acid) fibres for biomedical applications. Water-soluble drug, Rhodamine 6G or protein bovine serum albumin, loaded calcium carbonate microparticles were successfully incorporated in PLGA fibres and a bead and string structured composite fibres.

Current plastics are mostly derived from petrochemical sources, as it is a finite resource renewable replacements are sought after. Polymers derived from cyclic esters such as; lactide, valerolactone and caprolactone are of interest. An industrially viable method of producing stereocontrolled polylactide (PLA) from rac-lactide is desired. Previous work on poly(cyclic esters) is overviewed in chapter 1 with an emphasis upon PLA. Chapter 2 reports the coordination of Ti(OiPr)4 to homo/piperazine bridged bis(phenol) (salan) ligands. Under ambient conditions bimetallic structures were produced and a steric dependent equilibrium system is discussed. Forcing conditions resulted in monometallic homopiperazine salan complexes. Their application for the ring-opening-polymerisation (ROP) of rac-lactide is investigated. Homo/piperazine salan titanium catecholates were synthesised and their cytotoxicity investigated by collaborators. Chapter 3 details the synthesis of monometallic homopiperazine salan zirconium/hafnium isopropoxide complexes. Their utility for the ROP of rac-lactide in solution and solvent free systems are discussed. Bimetallic or tetrametallic solid state structures from attempts to coordinate Zr(IV)/Hf(IV) metals to piperazine salan ligands are also discussed. Chapter 4 discusses the complexation of AlMe3 with homopiperazine salan ligands. The resulting monometallic complexes were inactive for the ROP of lactide. Benzyl alcohol derivatives were synthesised and trialled for solvent free ROP of rac-lactide, δ-valerolactone, ε-caprolactone. Co-polymerisations were investigated and a tri-block polymer of poly(ε-caprolactone/δ-valerolactone/rac-lactide) was prepared. Chapter 5, trans-1,4-DACH salen ligands were synthesised and investigated as ligands with Al(III), Ti(IV), Zr(IV), and Zn(II) metal centres. Bimetallic Al(III) and Ti(IV) structures were characterised and trialled for the ROP of rac-lactide. Isotactic PLA was reported for aluminium complexes, dependent upon phenoxy substituents, and these polymerisations were shown to be immortal in nature. Chapter 6 details the synthesis of trans-1,2-DACH salalen ligands which were complexed to AlMe3, these initiators were investigated for the solution ROP of rac-lactide. The further synthesis of benzyloxy derivatives is also reported and they were utilised for solution and solvent free polymerisations of rac-lactide. The initiator’s behaviour is discussed with respect to varying amine and imine groups.