Living radical polymerization has proved to be a powerful tool for the synthesis of polymers as it allows for a high degree of control over the polymer microstructure and the synthesis of tailored molecular architectures. Although it has great potential, its use on an industrial scale is limited due to environmental and economical aspects. Nitroxide mediated polymerization is explored to bring this technology closer to adoption in commercial applications. One of the obstacles encountered using nitroxide mediated polymerization in microemulsion systems is the difficulty in controlling both the particle size and target molecular weight. Due to the nature of the formulation, a decrease in the target molecular weight is coupled to an increase in the particle size. For many applications, it is important to be able to design polymer particles with both specifications independently. Strategies to decouple these two properties and processing conditions required for targeting a range of particle sizes and molecular weights for n butyl acrylate latexes are presented. Furthermore, in an attempt to reduce the large amounts of surfactant typically used in microemulsions, these methods were explored at low surfactant to monomer ratios (0.2 to 0.5 by wt.) in order to reduce the costs associated with excess surfactant and post processing steps for surfactant removal (high surfactant levels also give poor water-resistance in coatings). Stable nanolatexes with particle sizes <40 nm have been obtained by other groups using NMP in microemulsions with SG1 but have done so by using much higher surfactant to monomer ratios (~2.5 by wt.) and at much lower solids content (6 10 wt. %). In this work, molecular weights of 20,000 to 80,000 g∙mol-1 were targeted and stable, n-butyl acrylate microemulsions with particle sizes ranging from 20 120 nm were prepared at a solids content of 20 wt. % using much lower surfactant concentrations. Although numerous studies have shown the effects of process parameters on particle sizes and methods to control the molecular weight, the decoupling of the molecular weight and particle size effect in NMP microemulsions under these conditions has not been done to this extent. In copolymer systems, nitroxide mediated polymerization also provides an efficient method to synthesize well defined block copolymers. Random copolymers are widely used as protective colloids, but the use of block copolymers for these applications has not been well studied. It is unclear what effects do the importance of a narrow molecular weight distribution and purity of block copolymers have on their performance as protective colloids. In order to investigate this, a range of block copolymers with different properties would need to be synthesized for systematic analysis. The direct synthesis of polystyrene b poly(acrylic acid) copolymers of varying lengths and compositions was successful by use of nitroxide mediated polymerization in bulk and solution polymerization. The characterization of these amphiphilic block copolymers was explored by titration and nuclear magnetic resonance spectroscopy. / Thesis (Master, Chemical Engineering) -- Queen's University, 2012-09-28 15:43:00.513

Novel imidazole-containing polyelectrolytes based on poly(1-vinylimidazole) (poly(1VIM)) were functionalized with various hydroxyalkyl-substituents to investigate the influence of charge density and hydrogen bonding on nonviral DNA delivery.  Copolymers with higher charge densities exhibited increased cytotoxicity, whereas increased hydroxyl concentrations remained nontoxic.  DNA binding affinity increased with increased charge densities and increased hydroxyl content.  Dynamic light scattering determined the copolymers which delivered DNA most effectively maintained an intermediate binding affinity between copolymer and DNA.  Copolymers containing higher charge densities or hydroxyl concentrations bound DNA too tightly, preventing its release inside the cell.  Copolymers with lower charge densities failed to protect the DNA from enzymatic degradation.  Tuning hydrogen bonding concentration allowed for a less toxic and more effective alternative to conventional, highly charged polymers for the development of nonviral DNA delivery vehicles.  The synthesis of amine-containing imidazolium copolymers functionalized with low concentrations of folic acid enabled the investigation of additional polymer modifications on nonviral gene delivery.   Functionalization of 1VIM with various hydroxyalkyl and alkyl groups and subsequent conventional free radical polymerization afforded a series of imidazolium-containing polyelectrolytes.  Hydroxyl-containing homopolymers exhibited higher thermal stabilities and lower T_g's compared to the respective alkyl-analog.  X-ray scattering demonstrated the polarity of the hydroxyl group facilitated solvation of the electrostatic interactions disrupting the nanophase-separated morphology observed in the alkylated systems.  Impedance spectroscopy determined hydroxyl-containing imidazolium homopolymers displayed higher ionic conductivities compared to the alkyl-containing analogs which was attributed to increased solvation of electrostatic interactions in the hydroxyl analogs. Beyond functionalizing 1VIM monomers and homopolymers to tailor various properties, the synthesis of novel architectures in a controlled fashion remains difficult due to the radically unstable N-vinyl propagating radical.  The regioisomer 4-vinylimidazole (4VIM) contains two resonance structures affording increased radical stability of the propagating radical.  Nitroxide-mediated polymerization (NMP) and atom transfer radical polymerization (ATRP) failed to control 4VIM homopolymerizations; however, reversible addition-fragmentation chain transfer (RAFT) demonstrated unprecedented control.  Linear pseudo-first order kinetics were observed and successful chain extension with additional 4VIM suggested preservation of the trithiocarbonate functionality. Effectively controlling the polymerization of 4VIM enabled the design of amphoteric block copolymers for emerging applications.  The design of ABA triblock copolymers with 4VIM as a high T_g supporting outer block and di(ethylene glycol) methyl ether methacrylate (DEGMEMA) as a low T_g, inner block, required the development of a new difunctional RAFT chain transfer agent (CTA).  The difunctional CTA successfully mediated the synthesis of the ABA triblock copolymer, poly(4VIM-b-DEGMEMA-b-4VIM), which exhibited microphase separated morphologies.  The amphoteric nature of the imidazole ring required substantially lower concentrations of outer block incorporation compared to traditional triblock copolymers to achieve similar mechanical properties and microphase separated morphologies. / Ph. D.

Cellulose is the most abundant renewable polymer on the planet and there is great interest in expanding its use beyond its traditional applications. However, its hydrophilicity and insolubility in most common solvent systems are obstacles to its widespread use in advanced materials. One way to counteract this is to attach hydrophobic polymer chains to cellulose: this allows the properties of the copolymer to be tailored by the molecular weight, density, and physical properties of the grafts. Two methods were used here to synthesize the graft copolymers: a ‘grafting-from’ approach, where synthetic chains were grown outward from bromoester moieties on cellulose (Cell-BiB) via Cu(0)-mediated polymerization; and a ‘grafting-to’ approach, where fully formed synthetic chains with terminal sulfide functionality were added to cellulose acetate with methacrylate functionality (CA-MAA) via thiol-ene Michael addition. The Cell-BiB was synthesized in the ionic liquid 1-butyl-3-methylimidazolium chloride and had a degree of substitution of 1.13. Polymerization from Cell-BiB proceeded at similar but slightly slower rate than an analogous non-polymeric initiator (EBiB). The average graft density of poly(methyl acrylate) chains was 0.71 chains/ring, with a maximum of 1.0 obtained. The graft density when grafting poly(methyl methacrylate) was only 0.15, and this appeared to be due to the slow initiation of BiB groups. Using EBiB to model the reaction and improve the design should allow this to be overcome. Chain extension experiments demonstrated the living behaviour of the polymer. The CA-MAA was synthesized by esterification with methacrylic acid. Reactions of CA-MAA with thiophenol and dodecanethiol resulted in quantitative addition of the thiol to the alkene. The grafts were synthesized by Cu(0)-mediated polymerization from a bifunctional initiator containing a disulfide bond, followed by reduction to sulfides. The synthetic polymers were successfully grafted to CA-MAA but the grafting yield was limited by the low sulfide functionality. Better retention of sulfide functionality is necessary for more efficient grafting. / Thesis (Master, Chemical Engineering) -- Queen's University, 2013-05-27 16:21:03.874

Reversible addition-fragmentation transfer (RAFT) was used as a controlling technique for studying the aqueous heterophase polymerization. The polymerization rates obtained by calorimetric investigation of ab initio emulsion polymerization of styrene revealed the strong influence of the type and combination of the RAFT agent and initiator on the polymerization rate and its profile. The studies in all-glass reactors on the evolution of the characteristic data such as average molecular weight, molecular weight distribution, and average particle size during the polymerization revealed the importance of the peculiarities of the heterophase system such as compartmentalization, swelling, and phase transfer. These results illustrated the important role of the water solubility of the initiator in determining the main loci of polymerization and the crucial role of the hydrophobicity of the RAFT agent for efficient transportation to the polymer particles. For an optimum control during ab-initio batch heterophase polymerization of styrene with RAFT, the RAFT agent must have certain hydrophilicity and the initiator must be water soluble in order to minimize reactions in the monomer phase. An analytical method was developed for the quantitative measurements of the sorption of the RAFT agents to the polymer particles based on the absorption of the visible light by the RAFT agent. Polymer nanoparticles, temperature, and stirring were employed to simulate the conditions of a typical aqueous heterophase polymerization system. The results confirmed the role of the hydrophilicity of the RAFT agent on the effectiveness of the control due to its fast transportation to the polymer particles during the initial period of polymerization after particle nucleation. As the presence of the polymer particles were essential for the transportation of the RAFT agents into the polymer dispersion, it was concluded that in an ab initio emulsion polymerization the transport of the hydrophobic RAFT agent only takes place after the nucleation and formation of the polymer particles. While the polymerization proceeds and the particles grow the rate of the transportation of the RAFT agent increases with conversion until the free monomer phase disappears.<br><br> The degradation of the RAFT agent by addition of KPS initiator revealed unambigueous evidence on the mechanism of entry in heterophase polymerization. These results showed that even extremely hydrophilic primary radicals, such as sulfate ion radical stemming from the KPS initiator, can enter the polymer particles without necessarily having propagated and reached a certain chain length. Moreover, these results recommend the employment of azo-initiators instead of persulfates for the application in seeded heterophase polymerization with RAFT agents.<br><br> The significant slower rate of transportation of the RAFT agent to the polymer particles when its solvent (styrene) was replaced with a more hydrophilic monomer (methyl methacrylate) lead to the conclusion that a complicated cooperative and competitive interplay of solubility parameters and interaction parameter with the particles exist, determining an effective transportation of the organic molecules to the polymer particles through the aqueous phase. The choice of proper solutions of even the most hydrophobic organic molecules can provide the opportunity of their sorption into the polymer particles. Examples to support this idea were given by loading the extremely stiff fluorescent molecule, pentacene, and very hydrophobic dye, Sudan IV, into the polymer particles.<br><br> Finally, the first application of RAFT at room temperature heterophase polymerization is reported. The results show that the RAFT process is effective at ambient temperature; however, the rate of fragmentation is significantly slower. The elevation of the reaction temperature in the presence of the RAFT agent resulted in faster polymerization and higher molar mass, suggesting that the fragmentation rate coefficient and its dependence on the temperature is responsible for the observed retardation. / Um neue Materialien mit außergewöhnlichen Eigenschaften zu erstellen, muss man in der Lage sein, die Struktur der Moleküle zu kontrollieren, aus denen die Materialien bestehen. Für das Maßschneidern solcher neuer Eigenschaften besitzen Polymere ein großes Potenzial: Dies sind sehr lange Moleküle, die aus einer großen Zahl von kleineren Einheiten aufgebaut sind. Proteine und DNS sind Beispiele für natürliche Polymere; Plastik und Gummi sind Beispiele für künstliche Polymere. Letztere werden üblicherweise durch das Zusammenfügen einer Reihe von kleineren Molekülen, den Monomeren, hergestellt. Schon lange versuchen Wissenschaftler, die Anordnung, Anzahl und Art dieser Monomere zu kontrollieren, die sich in der Struktur der Polymermoleküle widerspiegeln. Die gebräuchlichste Methode zur kommerziellen Produktion von Polymeren ist die so genannte freie radikalische Polymerisation. Die Strukturkontrolle durch diese Methode ist jedoch relativ schwierig und wurde maßgeblich erst im letzten Jahrzehnt entwickelt. Trotz der Existenz einiger effektiver Kontrollmethoden ist ihre industrielle Anwendung bislang sehr beschränkt, weil sie nicht für die Emulsionspolymerisation verwendbar sind. Die Emulsionspolymerisation ist die gängigste Technik in der industriellen Produktion von Polymeren. Es handelt sich dabei um ein vergleichsweise umweltfreundliches Verfahren, denn es werden keine organischen Lösungsmittel verwendet. Stattdessen dient Wasser als Lösungsmittel, in dem die Polymere in Form von kleinen, fein verteilten Partikeln vorliegen. In der Natur kommt dieses Prinzip beispielsweise in Pflanzen bei der Bildung von Kautschuk - allgemein als Latex bezeichnet - vor. Schließlich ist die Emulsionspolymerisation einfach durchzuführen: Das Produkt ist in vielen Fällen gebrauchsfertig, und es gibt viele technische Vorteile im Vergleich zu anderen Herstellungsprozessen.<br><br> Doch bevor die Probleme beim Einsatz von Kontrollmethoden in der Emulsionspolymerisation gelöst werden können, müssen erst ihre Ursachen geklärt werden. Dies ist eine unverzichtbare Vorraussetzung zum Übertragen von Forschungsergebnissen auf das tägliche Leben.<br><br> Ziel dieser Arbeit ist die Untersuchung der Probleme, die für die kontrollierte radikalische Polymerisation in Emulsion von Bedeutung sind. Die wichtigste Fragestellung in der Emulsionspolymerisation zielt auf die Löslichkeit der Reaktionskomponenten in den verschiedenen Phasen, wie z.B. in Wasser oder in den Polymerpartikeln. Die Kontrollmethode der Wahl für diese Arbeit ist "Reversibler Additions-Fragmentierungs Transfer" (RAFT). Die RAFT-Methode ist die modernste Kontrollmethode, und sie ist für viele Reaktionsbedingungen und viele Arten von Monomeren anwendbar.

Atom transfer radical polymerization (ATRP) is one of the most commonly employed techniques for controlled radical polymerization. ATRP has great potential for the development of new materials due to the ability to control molecular weight and polymer architecture. To fully utilize the potential of ATRP as polymerization technique, the mechanism and the dynamics of the ATRP equilibrium must be well understood. In this thesis, various aspects of the ATRP process are explored through both laboratory experiments and computer modeling. Solvent effects, the limit of control and the use of iron as the mediator have been investigated. It was shown for copper mediated ATRP that the redox properties of the mediator and the polymerization properties were significantly affected by the solvent. As expected, the apparent rate constant (kpapp) increased with increasing activity of the mediator, but an upper limit was reached, where after kpapp was practically independent of the mediator potential. The degree of control deteriorated as the limit was approached. In the simulations, which were based on the thermodynamic properties of the ATRP equilibrium, the same trend of increasing kpapp with increasing mediator activity was seen and a maximum was also reached. The simulation results could be used to describe the limit of control. The maximum equilibrium constant for controlled ATRP was correlated to the propagation rate constant, which enables the design of controlled ATRP systems. Using iron compounds instead of copper compounds as mediators in ATRP is attractive from environmental aspects. Two systems with iron were investigated. Firstly, iron/EDTA was investigated as mediator as its redox properties are within a suitable range for controlled ATRP. The polymerization of styrene was heterogeneous, where the rate limiting step is the adsorption of the dormant species to the mediator surface. The polymerizations were not controlled and it is possible that they had some cationic character. In the second iron system, the intention was to investigate how different ligands affect the properties of an ATRP system with iron. Due to competitive coordination of the solvent, DMF, the redox and polymeri­zation properties were not significantly affected by the ligands. The differences between normal and reverse ATRP of MMA, such as the degree of control, were the result of different FeIII speciation in the two systems. / QC 20110406

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

Le transfert de gènes consiste en l’introduction d’acides nucléiques au sein de cellules afin de modifier leur activité dans un but essentiellement thérapeutique. Pour préserver le matériel génétique de toute dégradation, il faut recourir à des vecteurs. Parmi ceux-ci, les polymères cationiques sont très prometteurs, en particulier, la polyéthylènimine, considérée comme le vecteur non-viral de référence. Néanmoins, il présente une cytotoxicité élevée. Ainsi, de nombreuses recherches ont pour but d’identifier et de développer de nouveaux polymères combinant efficacité de transfection et haute viabilité cellulaire. Cette thèse vise le développement de méthodes d’ingénierie macromoléculaire donnant accès à une large gamme de dérivés à base de polyvinylamine et l’évaluation de leurs performances en tant que vecteurs de transfection. Différentes techniques de polymérisation radicalaire conventionnelle et contrôlée ont été mises au point afin de synthétiser des (co)polymères à base de polyvinylamine constitués d’amines primaires et secondaires. L’efficacité du transfert d’ADN plasmidique et la viabilité cellulaire ont été évaluées sur des cellules HeLa. L’influence de différents paramètres macromoléculaires sur les performances de transfection a été investiguée. Cette étude a permis de démontrer que certains dérivés de polyvinylamine possédaient une efficacité de transfection aussi élevée que la PEI tout en étant moins toxique. De manière générale, ce travail rend compte du haut potentiel des (co)polyvinylamines en tant que vecteurs pour le transfert de gènes. / Gene transfection consists in the introduction of genetic materials (DNA or RNA) in cells in order to modulate the cell activity, with therapeutic purposes in most cases. To deliver the genetic materials into cells without degradation, vectors are necessary. Among them, cationic polymers are promising candidates. For instance, polyethylenimine has emerged as a gold standard due to its high transfection ability. Nevertheless, this polymer exhibits high cytotoxicity, and current research aims at identifying and developing new polymers with improved cell viability and high gene transfer efficiency. In this context, the aim of this thesis was to develop efficient macromolecular engineering tools to prepare a library of polyvinylamine-containing (co)polymers and to evaluate their performances as DNA carriers. Consequently, free radical polymerization (FRP) and controlled radical polymerization (CRP) have been explored and a series of (co)polyvinylamines, containing primary and secondary amines, as well as vinylimidazole and guanidine moieties, have been synthesized. The transfection efficiency of plasmid DNA (pDNA) and cell viability were evaluated on HeLa cells. The influence of different macromolecular parameters such as molar mass, molar mass distribution and composition, was also studied. The most promising polymers for pDNA transfection were also tested for siRNA delivery and on other cell lines. Overall, several polymers were competitive with PEI regarding the transfection efficiency but were much less toxic. (Co)polyvinylamines, which have often been disregarded for transfection purposes, should definitely be considered as valuable gene carriers.

Due in large part to the growth and development of reliable surface characterization techniques, as well as to advances in the physical and chemical techniques used to modify surfaces, the technology of surface modification has seen rapid expansion over the past two decades. A major thrust of this research is the growth of controlled/"living" polymeric brushes from the surface of various substrates, an advance that promises to be a facile and reproducible way of altering surface properties. A unique initiator bearing ATRP (atom transfer radical polymerization), cleavage, and condensation functionalities was prepared and attached to the hydrolyzed surface of silica gel. Preliminary results indicate that control of reversibly terminated grafts of varying degrees of polymerization with polydispersity indices approaching 1.5 can be readily achieved-significant findings in the quest to design desired surface characteristics. Important physical characteristics may also be altered by way of varying molecular topologies. In the second major research thrust, the use of self-assembly to construct such topologies in the form of pseudorotaxanes fashioned from diverse macrocycles with multifarious guest ions is discussed. While the underlying goal was to investigate and understand the mode of complexation based on such environmental factors as substituent affects and neighboring group influences, new insight was gained on the synthetic manipulation of cooperative events-events that freely occur in nature. The complexation behavior of several functionalized bis-(meta-phenylene)-32-crown-10 macrocycles with various paraquat guest moieties was. As expected, studies indicated that electron-donating substituents on the crown ether drive association, a likely result of increased p -p interactions among host and guest species. The association between a bicyclic macrocycle and dimethyl paraquat was also investigated. Not surprisingly, binding of paraquat by the bicyclic was much stronger than the binding found in analogous macrocycles. Lastly, the endgroup functionalization of poly(propyleneimine) dendrimers with two crown ether macrocycles was performed and the complexation with host-specific guests studied. Curiously, two extreme binding regimes were found: the larger 32-membered crown ether assembly displayed anti-cooperative behavior upon complexation with paraquat, while the smaller 24-membered macrocyclic system exhibited cooperative effects with 2o ammonium ions. These cooperative results are among the very first described for non-biological systems and hint at their potential use in developing highly efficient, synthetically designed supramolecular systems. / Master of Science

L'objectif de cette thèse est d'élaborer et de développer un type de membranes polymères qui peuvent se réparer de manière autonome en cas de fissures. Si elles ne sont pas détectées, ces fissures peuvent poser des problèmes notamment pour des applications médicales. Dans une première partie, une membrane polymère dynamique à base de micelles de copolymère tribloc ABA a été préparée. Le bloc "A" est représenté par le poly (styrene-co-acrylonitrile), copolymère bloc mécaniquement robuste, et un bloc "B" relativement mou et souple, le poly (ethylene oxide). Lorsqu'une pression est appliquée à la membrane, sa morphologie peut être ajustée grâce à la nature compressible des micelles, ainsi que les ponts dynamiques intermicellaires. Une gamme de porosités accessible peut être régulée par la pression et de manière à contrôler la performance de filtration. La même nature dynamique a également été utilisée pour montrer une réparation autonome entrainée par la pression. L'efficacité du processus de réparation dépend de la taille des fissures, de la valeur de pression et de la durée d'application de la pression. En utilisant la propriété d'auto-réparation de la membrane ci-dessus, le processus « Direct Mode Translocation » de nanoparticules a également été étudié. Quatre classes différentes de nanoparticules ont été utilisées avec diverses propriétés intrinsèques et extrinsèques. Les conclusions de ces travaux prouvent que les caractéristiques de taille, de forme et de surface des nanoparticules ainsi que la force exercée régissent le processus de translocation. Dans une seconde partie, un revêtement 2D et 3D réversible basé sur l'auto-assemblage de micelles de copolymère dibloc constitué d'un poly (methyl methacrylate) (PMMA) et du poly (n-octadecyl methacrylate) (PODMA) blocs a été développé. L'assemblage de micelles est réalisé par l'effet "Zipper", grâce aux longues chaînes pendantes du bloc PODMA. Le même effet "Zipper" permet d'enlever facilement le revêtement par lavage dans un solvant sélectif, donnant ainsi la possibilité de modifier la surface d'un substrat plusieurs fois de manière réversible. La cristallisation à température ambiante du bloc PODMA offre la possibilité d'avoir un revêtement auto-réparable thermiquement sans affecter la morphologie globale des micelles. Enfin, une dernière partie a été conceptualisée, dans laquelle l'auto-réparation se fait par « nano-gel » encapsulés et dispersés dans une membrane. Le « nano-gel » est à base d'un copolymère hydrophile en forme d'une étoile partiellement réticulée et qui doit être synthétisée par la technique de "Reversible Addition-Fragmentation Transfer" (RAFT) polymérisation. La synthèse d'un agent RAFT avec 4 bras pour la polymérisation a été accomplie, cependant, des travaux sont encore nécessaires pour valider la voie de synthèse vers la synthèse de « nano-gel » ainsi que son application pour le processus d'auto-réparation. / The objective of this thesis is to develop such kind of polymeric membranes which can repair themselves autonomously in an event of damage. Such damage in a membrane, if left undetected can pose serious health issues in some of the intended applications. In the first approach, a dynamic polymeric membrane based on ABA type triblock copolymer micelles has been prepared. The block “A” is represented by mechanically robust poly(styrene-co-acrylonitrile) copolymer while block “B” by relatively soft and flexible poly(ethylene oxide). When pressure is applied to the membrane, its morphology can be fine-tuned thanks to the compressible nature of micelles as well as intermicellar dynamic bridges. A range of porosities are accessible which can be regulated by pressure and thereby controlling the filtration performance. The same dynamic nature has also been utilized to display an effective pressure driven autonomous healing. The efficiency of healing process has been found to be dependent on the extent of damage, pressure value and time duration of application of pressure. Using the self-healing property of above membrane, “Direct Mode Translocation” of nanoparticles has also been studied. Four different classes of nanoparticles were used with varied intrinsic and extrinsic properties. The findings of the work prove that the size, shape and surface characteristics of the nanoparticles as well as the applied force govern the translocation process. In a second approach, a 2D and 3D reversible coating based on the self-assembly of micelles of diblock copolymer consisting of poly(methyl methacrylate) (PMMA) and poly(n-octadecyl methacrylate) (PODMA) blocks have been developed. The assembly of micelles is accomplished via so called “Zipper” effect, thanks to the long pendant chains of PODMA block. The same “zipper” effect plays the role of removing the coating easily by washing in a selective solvent, thus giving the ability to alter the surface of substrate for many times in reversible manner. The room temperature crystallization of PODMA block provides huge implications for a thermally assisted self-healing coating without affecting the global micelle morphology. Finally, another approach has been conceptualized in which self-healing occurs via encapsulated nano-gel dispersed within a membrane. The nano-gel is based on a partially crosslinked hydrophilic star shaped block copolymer which has to be synthesized by “Reversible Addition-Fragmentation Transfer” (RAFT) polymerization technique. The synthesis of a 4- arm RAFT agent for polymerization has been accomplished however ; a substantial amount of work is still needed to validate the synthetic route towards the nano-gel synthesis as well as its further application for the self-healing process.

1,8-bis(phenylimino)-3,6-ditertbutyl-carbazole is synthesized and characterized, which can be complexed with copper(II) halide by deprotonation and transmetallation. The resulting copper complexes enable to polymerize MMA through RATRP process.