Polystyrene (PS) is an important commodity polymer. In its most commonly used form, PS is a high molecular weight linear polymer, typically produced through free-radical polymerization, which is a well understood and robust process. This process produces a high molecular weight, clear thermoplastic that is hard, rigid and has good thermal and melt flow properties for use in moldings, extrusions and films. However, polystyrene produced through the free radical process has a very broad molecular weight distribution, which can lead to poor performance in some applications. To this end, nitroxide-mediated radical polymerization (NMRP) can synthesize materials with a much more consistently defined molecular architecture as well as relatively low polydispersity than other methods. NMRP involves radical polymerization in the presence of a nitroxide mediator. This mediator is usually of the form of a stable radical which can bind to and disable the growing polymer chain. This will “tie up” some of the free radicals forming a dynamic equilibrium between active and dormant species, through a reversible coupling process. NMRP can be conducted through one of two different processes: (1) The bimolecular process, which can be initiated with a conventional peroxide initiator (i.e. BPO) but in the presence of a stable nitroxide radical (i.e. TEMPO), which is a stable radical that can reversibly bind with the growing polymer radical chain, and (2) The unimolecular process, where nitroxyl ether is introduced to the system, which then degrades to create both the initiator and mediator radicals. Based on previous research in the group, which included experimental investigations with both unimolecular and bimolecular NMRP under various conditions, it was possible to build on an earlier model and come up with an improved detailed mechanistic model. Additionally, it was seen that certain parameters in the model had little impact on the overall model performance, which suggested that their removal would be appropriate, also serving to reduce the complexity of the model. Comparisons of model predictions with experimental data both from within the group and the general literature were performed and trends verified. Further work was done on the development of an additionally reduced model, and on the testing of these different levels of model complexity with data. The aim of this analysis was to develop a model to capture the key process responses in a simple and easy to implement manner with comparable accuracy to the complete models. Due to its lower complexity, this substantially reduced model would me a much likelier candidate for use in on-line applications. Application of these different model levels to the model-based D-optimal design of experiments was then pursued, with results compared to those generated by a parallel Bayesian design project conducted within the group. Additional work was done using a different optimality criterion, targeted at reducing the amount of parameter correlation that may be seen in D-optimal designs. Finally, conclusions and recommendations for future work were made, including a detailed explanation of how a model similar to the ones described in this paper could be used in the optimal selection of sensors and design of experiments.

A non-crosslinking approach that covalently bonds nitroxide polymer brushes onto the ITO substrates via surface-initiated atom transfer radical polymerization (ATRP) was develpoed. Since the indium tin oxide (ITO)-silane covalent bonding providesvery strong chemical bonds to adsorb the nitroxide polymer brushes on ITO, it prevents polymers from dissolving into electrolyte solvent and thus improves its electrochemical properties. Moreover, micro-contact printing technology was used to pattern nitroxide polymer brushes on an ITO surface for the potential application in microbatteries. The morphology of electrodes was observed by atomic force microscopy.The electrochemical properties of the cathode were also studies.

Nitroxide polymer brushes grafted on silica nanoparticles as binder-free cathode for organic radical battery have been investigated. Scanning electron microscopy, transmission electron microscopy, infrared spectroscopy and electron spin resonance confirm that the nitroxide polymer brushes are successfully grafted onto silica nanoparticles via surface-initiated atom transfer radical polymerization. The thermogravimetric analysis results indicate that the onset decomposition temperature of these nitroxide polymer brushes is found to be ca. 201 ◦C. The grafting density of the nitroxide polymer brushes grafted on silica nanoparticles is 0.74¡V1.01 chains nm−2. The results of the electrochemical quartz crystal microbalance indicate that the non-crosslinking nitroxide polymer brushes prevent the polymer from dissolving into organic electrolytes. Furthermore, the electrochemical results show that the discharge capacity of the polymer brushes is 84.9¡V111.1 mAh g−1 at 10 C and the cells with the nitroxide polymer brush electrodes have a very good cycle-life performance of 96.3% retention after 300 cycles.

Verdazyl radicals are a family of multicoloured stable free radicals. Aside from the defining backbone of four nitrogen atoms, these radicals contain multiple highly modifiable sites that grant them a high degree of derivatization. Despite having been discovered more than half a century ago, limited applications have been found for the verdazyl radicals and little is known about their chemistry. This thesis begins with an investigation to determine whether verdazyl radicals have a future as mediating agents in living radical polymerizations and progresses to their application as substrates for organic synthesis, an application that to date has not been pursued either with verdazyl or nitroxide stable radicals. The first part of this thesis describes the successful use of the 1,5-dimethyl-3-phenyl-6-oxoverdazyl radical as a mediating agent for styrene and n-butyl acrylate stable free radical polymerizations. The study of other verdazyl derivatives demonstrated the impact of steric and electronic properties of the verdazyl radicals on their ability to mediate polymerizations. The second part of this thesis outlines the initial discovery and the mechanistic elucidation of the transformation of the 1,5-dimethyl-3-phenyl-6-oxoverdazyl radical into an azomethine imine, which in the presence of dipolarophiles, undergoes a [3+2] 1,3-dipolar cycloaddition reaction to yield unique pyrazolotetrazinone structures. The reactivity of the azomethine imine and the scope of the reaction were also examined. The third part of this thesis describes the discovery and mechanistic determination of a base-induced rearrangement reaction that transforms the verdazyl-derived pyrazolotetrazinone cycloadducts into corresponding pyrazolotriazinones or triazole structures. The nucleophilicity, or the lack thereof, of the base employed leading to various rearrangement products was examined in detail. The final part of this thesis demonstrates the compatibility of the verdazyl-initiated cycloaddition and rearrangement reactions with the philosophy of diversity-oriented synthesis in generating libraries of heterocycles. A library of verdazyl-derived heterocycles was generated in a short amount of time and was tested non-specifically for biological activity against acute myeloid leukemia and multiple myeloma cell lines. One particular compound showed cell-killing activity at the 250 mM range, indicating future potential for this chemistry in the field of drug discovery.

Acrylic resins, synthesized from a mixture of monomers selected from the methacrylate, acrylate and styrene families, are the base polymer components for many automotive coatings due to their excellent chemical and mechanical properties. The low molecular weight polymers with reactive functionalities are made via high-temperature starved-feed free-radical solution semibatch terpolymerization, operating conditions that greatly promote the importance of secondary reactions, such as methacrylate depropagation, and acrylate backbiting, chain scission and macromonomer propagation. In this work, a generalized model for styrene/methacrylate/acrylate terpolymerization has been developed and formulated in the PREDICI software package and poorly understood high temperature mechanisms have been studied. Unknown rate coefficients for methacrylate depropagation, reactivity of acrylate macromonomer and penultimate copolymerization kinetics were determined via separate kinetic experiments. The generality of the terpolymerization mechanistic model was verified against data obtained under a range of polymerization conditions, and provides an exclusive insight into the kinetic complexity of methacrylate/styrene/acrylate terpolymerization at high temperatures. / Thesis (Ph.D, Chemical Engineering) -- Queen's University, 2010-04-28 19:56:36.906

Significant advances have been made in the understanding of living/controlled radical polymerization processes since their discovery in the early 1990’s. These processes enable an unprecedented degree of control over polymer architecture that was previously not possible using conventional radical polymerization processes, and this has made possible the synthesis of many new and interesting materials. However, there has been only limited success in commercializing these new methods. Recently there has been increased focus on the development of more industrially viable processes. Dispersed aqueous phase reactions have received much attention because these water-based processes have several technical, economic, and environmental benefits over the more common solution and bulk reactions that were originally developed. Likewise, there has been some investigation of using continuous reactors that have potential technical and economic benefits over the more commonly employed batch reactors. This thesis presents an in-depth study that combines the three aforementioned technologies: living/controlled radical polymerization, dispersed phase aqueous reactions, and continuous reactors. Specifically, the system of interest is a nitroxide-mediated miniemulsion polymerization reaction in a continuous tubular reactor to produce polymer latex. Design of the continuous tubular reactor is discussed in some detail with a focus on specific technical challenges that were faced in building a functional apparatus for this system. Scoping experiments are described which identified a significant effect of temperature ramping rate that is critical to understand when moving to larger scale reactors for this system. The unexpected phenomenon of room temperature polymerization initiated by ascorbic acid is also described. There is demonstration for the first time that bulk and miniemulsion polymers can be produced in a tubular reactor under controlled nitroxide-mediated polymerization conditions, and copolymers can be produced. A detailed residence time distribution study for the tubular reactor is also shown, and several interesting phenomena are discussed that have implications on the practical operating conditions of the tubular reactor. This particular study makes it clear that one should experimentally verify the residence time distribution within a continuous system with the reactants of interest, and that model systems may not give an accurate picture of the real system. / Thesis (Ph.D, Chemical Engineering) -- Queen's University, 2010-12-20 12:00:37.974

Functional water-soluble polymers find applications in a variety of fields including waste-water treatment, pharmaceuticals, cosmetics, drug delivery, and hygiene. Despite the increased demand for these products, understanding of their synthesis by free-radical aqueous-phase polymerization has lagged behind that of polymers produced in organic solvents. In this doctoral work, the free-radical batch and semibatch aqueous-phase polymerization of N-vinylpyrrolidone (NVP), N-vinylformamide (NVF), N-vinylimidazole (NVI) and quaternized vinylimidazole (QVI), as well as NVP polymerized in n-butanol, has been studied. Kinetic models are developed to describe monomer conversion and polymer molecular weight (MW) behaviour of these systems. The expressions developed from independent pulsed-laser studies for propagation (kp) and termination (kt) rate coefficients, including their variation with monomer concentration and conversion, are shown to provide an excellent description of aqueous-phase NVP polymerization. Polymerization of NVP in butanol and of NVF in water are well-represented by the base NVP model, with differences in polymerization rate and polymer MWs simply accounted for by the differences in kp for the systems, indicating that the kt behaviour must be quite similar. The NVI/QVI study demonstrates the importance of a pH-dependent degradative addition reaction to monomer for NVI, with polymerization behaviour identical to that of QVI for pH 1, an effect captured in the model developed to describe the system. The aqueous-phase copolymerization of NVP and NVF was also studied, and reactivity ratios were determined to be very close to unity. This information was combined with the kp and kt expressions used to describe NVP and NVF homopolymerizations, with no other additional parameters required to model the copolymerization rate, copolymer composition and copolymer MW. This result demonstrates that the improved homopolymerization knowledge of these water-soluble monomers can be easily extended to understand their behaviour in copolymerization. / Thesis (Ph.D, Chemical Engineering) -- Queen's University, 2011-12-21 16:05:14.904

Verdazyl radicals are a family of multicoloured stable free radicals. Aside from the defining backbone of four nitrogen atoms, these radicals contain multiple highly modifiable sites that grant them a high degree of derivatization. Despite having been discovered more than half a century ago, limited applications have been found for the verdazyl radicals and little is known about their chemistry. This thesis begins with an investigation to determine whether verdazyl radicals have a future as mediating agents in living radical polymerizations and progresses to their application as substrates for organic synthesis, an application that to date has not been pursued either with verdazyl or nitroxide stable radicals. The first part of this thesis describes the successful use of the 1,5-dimethyl-3-phenyl-6-oxoverdazyl radical as a mediating agent for styrene and n-butyl acrylate stable free radical polymerizations. The study of other verdazyl derivatives demonstrated the impact of steric and electronic properties of the verdazyl radicals on their ability to mediate polymerizations. The second part of this thesis outlines the initial discovery and the mechanistic elucidation of the transformation of the 1,5-dimethyl-3-phenyl-6-oxoverdazyl radical into an azomethine imine, which in the presence of dipolarophiles, undergoes a [3+2] 1,3-dipolar cycloaddition reaction to yield unique pyrazolotetrazinone structures. The reactivity of the azomethine imine and the scope of the reaction were also examined. The third part of this thesis describes the discovery and mechanistic determination of a base-induced rearrangement reaction that transforms the verdazyl-derived pyrazolotetrazinone cycloadducts into corresponding pyrazolotriazinones or triazole structures. The nucleophilicity, or the lack thereof, of the base employed leading to various rearrangement products was examined in detail. The final part of this thesis demonstrates the compatibility of the verdazyl-initiated cycloaddition and rearrangement reactions with the philosophy of diversity-oriented synthesis in generating libraries of heterocycles. A library of verdazyl-derived heterocycles was generated in a short amount of time and was tested non-specifically for biological activity against acute myeloid leukemia and multiple myeloma cell lines. One particular compound showed cell-killing activity at the 250 mM range, indicating future potential for this chemistry in the field of drug discovery.

The present thesis investigates some long standing problems in radical polymerization (RP). The major aim is to consider the feasibility of using simple techniques to provide more insight into the kinetics of RP. This can contribute to fundamental knowledge of radical polymerizations, particularly with respect to the mode of termination (λ), average termination rate coefficient (<kt>), chain-length dependence of termination (CLDT) and chain transfer through in-depth investigations of the rate of polymerization (Rp) and molar mass distribution (MMD), the latter especially via mass spectrometric (MS) analysis. The termination process was first investigated. Observation of changes of <kt> (or equivalently Rp) and MMD by a variety of factors such as solvent, monomer and initiator concentrations, temperature, pressure and growing radical size were explored. Non-classical kinetics and chain-length dependency of termination were confirmed. Accessibility of CLDT information was clearly evident. Although observed results meet fully with composite-model expectations, issues such as chain transfer were found to have an effect on the CLDT parameters determined from rate measurements. Specifically, dilute-solution polymerization of methyl methacrylate (MMA) in methyl isobutyrate (MIB) showed evidence of such an effect. Scaling of quantities that are experimentally accessible such as <kt> with DPn yield CLDT parameters in good agreement with what has been reported from recent PLP experiments. This was confirmed for several monomers. The temperature dependence of termination was also investigated and found to show evidence for CLDT. In contrast, the variation of <kt> with pressure did not demonstrate similarly strong CLDT effects. Evidence for and determination of chain transfer to MIB was also obtained. This was followed up by investigations into the important parameter λ using the MS technique. Surprisingly little is known about λ despite its long history and its apparent importance to polymer properties. Firstly, the robustness of using MS was explored, with the method passing numerous consistency checks. Although no large dependence of MS instrument was found, electrospray-ionization mass spectrometry (ESI-MS) provided best resolution. Second, the type of initiator, the initiator concentration and the solvent were found to have no measurable effect on λ, even when chain transfer occurred. In further work, increasing temperature seemed to have an influence on λ, leading to an increase in the proportion of disproportionation. However, pressure was found to have only a small influence on λ. The effect of monomer on λ was also studied. In the final part of this work, a preliminarily investigation into the viability of using Raman spectroscopic techniques to study auto-acceleration, also called the gel effect, for bulk MMA radical polymerization was presented. The results showed the possibility of using such a technique to follow the reaction to high conversion. The effect of temperature and initiator concentration on auto-acceleration were also presented. The outstanding results of this thesis are: (1) The application of CLDT theory to better understand rate results from low-conversion polymerizations. (2) In particular, the use of CLDT principles to explain termination activation energies across a range of monomers. (3) The validation of the MS method for quantitative determination of mode of termination by carrying out an array of consistency checks. (4) Showing that MS results are consistent with CLDT theory. (5) Utilization of the MS method for the first ever reliable measurement of the variation of mode of termination with temperature, pressure and monomer.

The advent of numerous tools, ease of techniques, and concepts related to nanotechnology, in combination with functionalization via simple chemistry has made gold important for various biomedical applications. In this dissertation, the development and characterization of planar gold surfaces with responsive hydrogel patterns for rapid point of care sensing and the functionalization of gold nanoparticles for drug delivery are highlighted. Biomedical micro- and nanoscale devices that are spatially functionalized with intelligent hydrogels are typically fabricated using conventional UV-lithography. Herein, precise 3-D hydrogel patterns made up of temperature responsive crosslinked poly(N-isopropylacrylamide) over gold were synthesized. The XY control of the hydrogel was achieved using microcontact printing, while thickness control was achieved using atom transfer radical polymerization (ATRP). Atomic force microscopy analysis showed that to the ATRP reaction time governed the pattern growth. The temperature dependent swelling ratio was tailored by tuning the mesh size of the hydrogel. While nanopatterns exhibited a broad lower critical solution temperature (LCST) transition, surface roughness showed a sharp LCST transition. Quartz crystal microbalance with dissipation showed rapid response behavior of the thin films, which makes them applicable as functional components in biomedical devices. The easy synthesis, relative biocompatibility, inertness, and easy functionalization of gold nanoparticles (GNPs) have made them useful for various biomedical applications. Although ATRP can be successfully carried out over GNPs, the yield of stable solution based GNPs for biomedical applications prove to be low. As an alternative approach, a novel method of ISOlating, FUnctionalizing, and REleasing nanoparticles (ISOFURE) was proposed. Biodegradable poly(β-amino ester) hydrogels were used to synthesize ISOFURE-GNP composites. ATRP was performed inside the composite, and the final hydrogel coated GNPs were released via matrix degradation. Response analysis confirmed that the ISOFURE method led to the increased stability and yield of the hydrogel coated ISOFURE-GNPs. The ISOFURE protocol was also utilized in functionalizing GNPs with enzyme catalase in the absence of a stabilizing reagent. Biotin-streptavidin affinity was used as the bioconjugation method. Activity analysis of the conjugated enzyme showed that the ISOFURE-GNPs showed enhanced biomolecular loading relative to solution based stabilizing reagent passivated GNPs.