Tesi sul tema "ATRP"

Photoinduced atom transfer radical polymerization (ATRP) was achieved using a simple household fluorescent lamp as the light source. In solution, methyl methacrylate could be polymerized to welldefined polymers; the photoinduced ATRP system did only convert monomers during irradiation and was inactive in the dark. In situ monitoring by UV-vis spectroscopy revealed the photoredox cycle between Cuᶦᶦ and Cuᶦ species. The linear development of the polymer number average molar mass with monomer conversion, the low dispersity as well as chain extension experiments showed the controlled nature of the polymerization. Photoinduced ATRP was also used to prepare homo- and block copolymer brushes and patterned brushes on surfaces by photoinduced surface-initiated ATRP (PSI-ATRP).

Sherrington and co-workers have shown that branched vinyl polymers can be synthesized by the addition of a chain transfer agent to a conventional free radical statistical copolymerisation of a vinyl and a divinyl monomer. In the presence of the chain transfer agent, the molecular weight of the primary chains is reduced, gelation can be suppressed and soluble, branched polymers are obtained as the sole product. Living polymerisation techniques offer a way to control the primary chain length without the need for a transfer agent simply by adjusting the monomer/initiator molar ratio. It is suggested that a significant degree of intramolecular cyclisation is the most likely explanation for the remarkable delay in the onset of gelation.

Unilever would like to explore the use of functional polysaccharides in then detergency formulations. The aim of this work was to grow various polymer chains of pre-determined lengths via Atom Transfer Radical Polymerisation (ATRP), from a water-soluble polysaccharide and to understand and improve the process. This work has given Unilever the option to fine tune polysaccharide-graft-copolymers for industrial use, whilst also satisfying a full investigation of these novel initiators, using new techniques developed within this work. In this respect, 'controlled or living' growth of chains from a post-modified, water soluble polysaccharide is reported for the first time using the following water soluble monomers: 4-styrene sulfonic acid sodium salt, 2-(dimethylamino)ethyl niethacrylate, poly(ethylene glycol) methacrylate and sodium methacrylate. Examples of psuedo first order control plots were seen, with linear increase in molecular weight (PDi values from 2 to 1.2) and with high monomer conversions. The addition of a non-ii ATRP appeared to increase monomer conversion.

La polimerizzazione radicalica a trasferimento di atomo (ATRP) è una tecnica versatile per la sintesi controllata di strutture macromolecolari. In questo lavoro, un sistema ad attivatore rigenerato mediante trasferimento elettronico (ARGET) ATRP viene presentato come un nuovo sistema green per la sintesi del polistirene (PS). Tale processo ARGET ATRP è catalizzato da rame e il sistema riducente è composto da acido ascorbico e carbonato di sodio. La miscela di solventi è composta da acetato di etile ed etanolo. Sorprendentemente, in specifiche condizioni ARGET ATRP, il PS è gelificato. La gelificazione è sorprendente poiché non sono stati aggiunti agenti ramificanti o reticolanti alla miscela di reazione e la loro formazione in situ è ​​stata esclusa. I risultati sperimentali portano all'ipotesi che si formi una rete olimpica con macrocicli compenetranti. Un brevetto è stato anche depositato con la sorprendente scoperta. In questa tesi viene studiato il meccanismo della gelificazione anomala, le evidenze a supporto dell'ipotesi della rete olimpica e la morfologia dei gel polistirenici ottenuti. Inoltre, è stata studiata anche l'addizione radicalica a trasferimento di atomo (ATRA) per sintetizzare acidi γ-alocarbossilici, partedo da da acidi α-alocarbossilici e alcheni. Gli acidi γ-alocarbossilici possono ciclizzare rapidamente per formare γ-lattoni, a seguito di una reazione di sostituzione della funzione alogenata da parte dell'acido carbossilico. Viene quindi proposta un nuovo acronimo per l'accoppiamento dell'ATRA con la successiva lattonizzazione (ATRA-L). Poiché la frazione alogenata viene persa rapidamente, l'ATRA-L consente l'uso di alcheni generalmente proibiti in ATRA. Infatti, a seguito di una reazione ATRA, l'alogeno del prodotto deve essere inattivo nei confronti di una seconda ATRA, altrimenti si otterrebbe un oligomero. In ATRA-L, l'alogeno viene perso e non ci sono restrizioni sulla scelta dell'alchene. È stato condotto uno studio approfondito della letteratura per trovare le reazioni correlate all'ATRA-L e per collegarle da un punto di vista comune. Viene quindi studiato un sistema ATRA-L catalizzato da rame in acqua, concentrandosi sull'effetto del pH sulla reazione, su come le variabili influenzano il sistema e sul meccanismo di reazione.
Atom transfer radical polymerization (ATRP) is a powerful technique for the synthesis of controlled macromolecular structures. In this work, an activator regenerated by electron transfer (ARGET) ATRP system is presented as a new green system for the synthesis of polystyrene (PS). This ARGET ATRP system is copper-catalyzed and the reducing system is composed of ascorbic acid and sodium carbonate. The solvent mixture is made up of ethyl acetate and ethanol. Surprisingly, in specific ARGET ATRP conditions, the PS gelled. The gelation is surprising since no branching nor crosslinking agents were added to the reaction mixture and their formation in situ was excluded. The experimental results lead to the hypothesis that an olympic network with interpenetrating macrocycles is formed. Furthermore, a patent was filed with the surprising discovery. In this thesis, it is studied the mechanism of the anomalous gelation, the supporting evidence to the olympic network hypothesis, and the morphology of the obtained PS gels. Besides, atom transfer radical addition (ATRA) was also studied to synthesize γ-halocarboxylic acids, starting from α-halocarboxylic acids and alkenes. The γ-halocarboxylic acids can rapidly cyclize to form γ-lactones, following a substitution reaction of the halogenated moiety by the carboxylic acid. A new acronym is then proposed for the combination of ATRA with the subsequent lactonization (ATRA-L). Since the halogenated moiety is rapidly lost, the ATRA-L allows the use of alkenes that are generally prohibited in ATRA. In fact, following an ATRA reaction, the halogen of the product is required to be inactive toward a second ATRA, otherwise an oligomer is obtained. In ATRA-L, the halogen is lost and there are no restrictions on the choice of the alkene. An in-depth study of the literature was done to find the reactions related to ATRA-L and to connect them from a common point of view. A copper-catalyzed ATRA-L system in water is then studied, focusing on the effect of the pH on the reaction, on how the variables affect the system, and on the reaction mechanism.

Preparation of functional bio-responsive polymer-based materials is the subject of increasing research efforts. Such type of materials could find broad applications in biology and medicine due to their promising performance in the areas of drug and biomolecule delivery, tissue engineering and diagnostic systems. The preparation of such materials has significantly advanced over last 20 years due to the development of reversible deactivation radical polymerization (RDRP) methods. Atom transfer radical polymerization (ATRP), the most often used RDRP procedure, is a versatile and powerful technique for preparation of various functional polymers. Even though ATRP showed great potential for design and synthesis of materials for biomedical applications, there are still many improvements and innovations that should be made in order to effectively utilize this method for production of useful biomaterials. This dissertation seeks to obtain the information required for improving the understanding of several aspects of ATRP, primarily focusing on controlling the polymerization in aqueous media, and how this contributes to the preparation of materials relevant to the biomedical field. Accordingly, this dissertation is divided into VIII chapters, where Chapter I is an introduction to the ATRP in aqueous media and reviews state of the art of aqueous ATRP and materials prepared by this method. Protein-polymer hybrids (PPH) are commercially available therapeutics for treatment of various diseases. Over the last decade the traditional procedure employed for preparation of PPHs had been “grafting-to”, i.e. attaching a preformed polymer to a biomolecule. This technique was challenged by a new approach “grafting-from”, where a well-defined polymer can be grown directly from a specific site on a biomolecule. This method significantly improves purification procedures and yield, which can potentially bring the cost down. Grafting-from requires performing the polymerization under aqueous conditions, optimally under biocompatible conditions. However, conducting ATRP in homogeneous aqueous media is inherently difficult due to multiple side reactions and high reaction rates.

The importance of finding new applications for cellulose‐based products has increased, especially to meet the demand for new environmentally friendly materials, but also since the digitalization of our society will eventually decrease the need for paper. To expand the application area of cellulose, modification to improve and/or introduce new properties can be a requisite. Thus, the focus of this study has been to achieve fundamental knowledge about polymer grafting of cellulose via well‐controlled radical polymerization. Cellulose, in the form of filter paper, has successfully been grafted via activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) of the monomers: methyl methacrylate, styrene, and glycidyl methacrylate. The advantages of ARGET ATRP are that only a small amount of a copper catalyst is required and the reaction can be performed in limited amount of air; yet, providing for relatively well‐controlled reactions. These benefits can render ARGET ATRP an attractive method for industrial utilization. The contact‐angle measurements of the grafted filter papers confirmed that the hydrophobicity of cellulose was significantly increased, even for shorter graft lengths. FT‐IR spectroscopy established that the amount of polymer successively increased with monomer conversion. High‐resolution FT‐IR microscopy (FT‐IRM) was proven to be a very useful technique for the analysis of cellulose substrates, displaying the spatial distribution of polymer content on cellulose fibers. The polymer was shown to be fairly homogenously distributed on the fiber. An initiator with a reducible disulfide bond rendered cleavage of the polymer grafts possible, employing mild reaction conditions. The cleaved grafts and the free polymers – formed from a sacrificial initiator in parallel to the grafting – were shown to have similar molar masses and dispersities, confirming that the grafts can be tailored by utilizing a sacrificial initiator. Moreover, the initiator content on filter paper and microcrystalline cellulose was assessed. A comparison between the two grafting techniques, grafting‐from cellulose via ARGET ATRP and grafting‐to cellulose via copper(I)‐catalyzed alkyne‐azide cycloaddition, was performed. To achieve a trustworthy comparison, the free polymer formed in parallel to the grafting‐from reaction was employed as the prepolymer in the grafting‐to approach, resulting in nearly identical graft length on the substrates for the two grafting methods. FT‐IRM analyses verified that under the selected conditions, the grafting‐from technique is superior to the grafting‐to approach with respect to controlling the distribution of the polymer content on the surface. The results were corroborated with X‐ray photoelectron spectroscopy.

QC 20121126

L'objectif de ce travail fut d'intensifier des procédés de polymérisation radicalaire par transfert d'atomes (ATRP) du méthacrylate de 2-(dimétylamino)éthyle (DMAEAMA) au moyen de technologies de microréaction (microréacteurs, micromélangeurs) et de paramètres de procédé (géométrie du réacteur, température, pression ... ).L'impact du prémélange sur les caractéristiques d'un copolymère statistique du DMAEMA et du méthacrylate de benzyle synthétisé dans des microréacteurs hélicoïdaux (CT) fut étudié en utilisant des principes différents de micromélange: bilamination, multilamination interdigitale (!MM) et jet d'impact. Des caractéristiques bien mieux contrôlées ont été obtenues avec !'IMM et l'intensification du procédé (Pl) a été clairement démontrée encomparaison d'un réacteur fermé ; en effet des masses molaires et conversions plus élevées ainsi que de plus faibles indices de polymolécularité (PDI) ont été obtenus pour des temps de passage inférieurs. Pour la production de PMADAME linéaire, le PI a également été réalisé par augmentation de la température et de la pression (jusqu'à 1 OO bars). Toutefois de trop hautes températures se sont avérées préjudiciables notamment pour de longs temps de passage. L'effet de l'augmentation du taux de cisaillement (via la longueur du réacteur) ne fut bénéfique qu'en régime dilué à un stade précoce de la réaction lorsque les masses molaires sont encore faibles. Comparés aux CT, un mélange interne favorisé par une technique d'inversion de flux s'est révélé être une stratégie très efficace pour réduire davantage le PDI et obtenir des masses molaires et conversions plus élevées. Des polymères branchés synthétisés en microréacteurs à inversion de flux (CFI) par ATRP en présence d'inimère présentèrent une structure plus ramifiée soulignant ainsi la supériorité des CFI sur les CT et réacteurs fermés en termes de PDI et d'efficacité de branchement. Considérant les caractéristiques des CFI, l'augmentation d'échelle des microréacteurs fut considérée par accroissement de leur diamètre. La productivité du procédé a été augmentée d'un facteur 4 tout en gardant un bon contrôle sur les caractéristiques macromoléculaires. Ainsi fut-il démontré que l'inversion de flux est un moyen très efficace pour contrebalancer l'effet négatif d'une augmentation du diamètre du microréacteur
The aim of this work was to intensify Atom Transfer Radical polymerization (ATRP) processes for the production of DMAEMA-based (co)polymers by relying on microreaction technology tools (microreactor, micromixers) and process parameters (reactor geometry, temperature, pressure ... ). Impact of premixing on macromolecular characteristics of P(DMAEMA-co-BzMA) synthesized in coiled tube (CT) microreactors was studied using different micromixing principles: bilamination, interdigital multilamination (IMM) and impact jet.Better controlled characteristics were obtained with !MM and process intensification (PI) was clearly demonstrated in comparison with batch mode as higher molecular weights, increased monomer conversions and lower polydispersity indices (PDI) were obtained for lower residence times. For the production of linear PDAEMA, PI was also achieved by application of elevated temperature and pressure (up to 100 bars). However, high temperature was found to be detrimental for long residence times. Effect of increased shear rate (i.e. reactor length) was found only beneficial in dilute regime at the early stage of the polymerization reaction when molecular weights are low. ln comparison with CT reactors, internal mixing promoted by flow inversion technique was found to be quite an effective strategy to reduce further PDI and obtain higher molecular weights and monomer conversions. Branched polymers synthesized by self condensing vinyl copolymerization (SCVCP) adapted to ATRP in tubular coil flow inverter (CFI) microreactors exhibited higher branched structure highlighting the superiority of CFI microreactor over CT and batch reactors in terms of PD! and branching efficiency. Finally, considering such features of CFI, attempt was made to scale-up microreactors by increasing their diameter. lt was found that process throughput can be increased by more than a factor of 4 while keeping a good control over macromolecular characteristics. Thus itwas demonstrated that flow inversion is quite effective to counter balance the detrimental effect of an increase in microreactor diameter

An investigation on the synthesis and properties of ferrocene-containing methacrylate monomer and polymer was carried out. Block copolymers of Ferrocenylmethyl Methacrylate with methyl, butil and esil methacrylate, were also prepared. The side-chain ferrocene-containing polymers and copolymers were prepared via atom transfer radical polymerization (ATRP). The glass transition temperature (Tg) values of the polymers and copolymers were measured by differential scan calorimetry (DSC).The thermal degradation behavior of copolymers was also studied and compared with the respective homopolymers. Cyclic voltammetry was employed to study the electrochemical properties. Preliminar electrochemical studies with a glassy carbon and Indium Tin Oxide electrodes modified with ferrocene-polymer conducted in aqueous and organic media are reported.

Orientador: Maria Isabel Felisberti
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química
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Resumo: Neste trabalho foram sintetizados copolímeros anfifílicos e em bloco baseados em metacrilato de sacarose (SMA) e nos metacrilatos de alquila (MAlq): metacrilato de etila (EMA), metacrilato de n-butila (BMA) e metacrilato de n-hexila (HMA), via polimerização radicalar por transferência de átomo (ATRP). Para tal, utilizou-se o sistema catalítico catalisador/desativador/iniciador/ligante constituído de CuBr/CuBr2/2,2,2-tribromoetanol/1,1,4,7,10,10-hexametiltrietilenotetramina. Este sistema catalítico é inédito para a polimerização do EMA, BMA e HMA e dos copolímeros. A polimerização dos MAlq pode ser considerada viva, pois seguiu cinética de polimerização de pseudo-primeira ordem, gerando-se polímeros com polidispersidade estreita (PDI<1,3), massa molar pré-determinada e funcionalizados. A constante de velocidade de polimerização segue a ordem kEMA>kBMA>kHMA, ordem inversa do relatado para a polimerização radicalar livre. Os copolímeros inéditos [P(MAlq-b-SMA)] foram sintetizados, apresentando distribuição bimodal de massa molar, devido à copolimerização parcial dos macroiniciadores. Supõe-se que as cadeias dos macroiniciadores fiquem encapsuladas em agregados dos copolímeros durante a síntese, impossibilitando sua reação. As análises de GPC utilizando os solventes DMF e THF para um mesmo copolímero resultaram em massas molares diferindo entre si de cerca de 10 vezes, sugerindo que os copolímeros se agregam ou se auto-organizam em solução de DMF/THF a 5DMF:95THF (v/v). O caráter anfifílico foi comprovado pela estabilização de uma emulsão de água e benzeno. Demais propriedades físico-químicas dos copolímeros, tais como solubilidade, intumescimento, temperatura de transição vítrea, variação da capacidade calorífica e estabilidade térmica, são distintas a dos respectivos macroiniciadores, evidenciando as mudanças de propriedades dos polímeros devido à inserção de SMA
Abstract: In the present work, amphiphilic block copolymers based on sucrose methacrylate (SMA) and the alkyl methacrylates (MAlq): ethyl methacrylate (EMA), n-butyl methacrylate (BMA) and n-hexyl methacrylate (HMA), were synthesized by atom transfer radical polymerization (ATRP), employing the CuBr/CuBr2/2,2,2-tribromoethanol/1,1,4,7,10,10-hexamethyltriethylenetetramine as a catalyst/ deactivator/initiator/ligant system. This is a novel system for polymerizing EMA, BMA, HMA and their copolymers. This MAlq polymerization may be considered "living", because it followed a pseudo-first order kinetics, which resulted in polymer with narrow polidispersity (PDI<1,3), controlled molar mass and preserved chain end functionality. The apparent rate constants of the polymerization were found to follow the kEMA>kBMA>kHMA order, which is the opposite order reported in free radical polymerization. The novel copolymers [P(MAlq-b-SMA)] were synthesized, showing bimodal molar mass distribution, due to partial PMAlq copolymerization. Possibly, PMAlq chains are encapsulated into copolymer aggregates during polymerization, stopping its reaction. GPC analysis with DMF and THF as solvents differed in molar mass about 10 times, suggesting that copolymers can organize in a 5DMF:95THF (v/v) DMF/THF solution. The stabilization of a water and benzene emulsion proved the copolymers amphiphilicity. Other copolymer physical-chemistry properties, such as solubility, swelling, glass transition temperature, heat capacity change and thermal stability are different when compared to the macroinitiators, which is an evidence of change in polymer properties due to SMA monomer insertion.
Mestrado
Físico-Química
Mestra em Química

A series of novel hetero-bifunctional linkers functionalised as ATRP initiators and protein and peptide-reactive agents has been prepared using standard synthetic techniques. A protein-based initiator has been applied to the initiation of living polymerisation in the synthesis of a novel bioconjugate. The linkers were designed based on the properties of polyethylene glycol and short alkyl chains coupled to either amine selective or thiol selective moieties for chemoselectivity, and bromoisobutyryl esters to facilitate atom transfer living polymerisation. The bi-functional linkers have also been coupled to short peptides based on the RGD bio-recognition sequence synthesised by standard solid phase peptide synthesis and the protein. Human Serum Albumin (HSA) using standard conditions to prepare peptide/protein-based ATRP initiators. Attempts at functionalising peptides with the N succinimidyl 4-(2-bromo-2- methylpropionyloxy) butanoate linker were unsuccessful. Model test of the protein based ATRP initiators in living polymerisation towards a novel strategy for bioconjugate synthesis was inconclusive as premature termination of the polymer chain was observed by MALDI analysis.

The aim of this work was to synthesise phosphorous-containing polymers with controlled molecular weights and low PDIs. Phosphorus functionality was introduced both by polymerising a phosphorus-containing monomer and by the reaction of functional polymers with phosphorous compounds in a postpolymerisation approach. Cu(0)-mediated SET-LRP was studied to ascertain if it could be used for the polymerisation of ethylene glycol containing monomers. When using copper wire as the source of metal, significant periods of inactivity or ‘induction’ time were observed at the beginning of the polymerisation. By altering the polymerisation temperature and the surface area of the copper, their affect on the ‘induction’ time was studied. SET-LRP was used to polymerise DEGMEMA, PEGA454, PEGMA475 and PEGMA1100, serving as model compounds for subsequent polymerisations of phosphorus-containing monomers. ATRP and SET-LRP were used to synthesise homopolymers of DEMOEP and copolymers of DEMOEP with both DEGMEMA and PEGMA475. ATRP resulted in well defined polymers with low PDIs, but SET-LRP of DEMOEP and DEMOEP/DEGMEMA exhibited high termination and high PDIs. By replacing DEGMEMA with PEGMA475, polymer synthesis by SET-LRP was much improved; termination was low, molecular weight growth was linear with respect to conversion and the final polymers had narrow molecular weight distributions. The control of these polymers by SET-LRP equalled those of ATRP. Deprotection chemistry was used to attempt the removal of the ethyl groups of the pendant phosphate groups in DEMOEP-containing polymers. Three different systems were used and their affect on the polymers was studied. Using a post-polymerisation modification strategy, reactive succinimidyl-ester containing polymers were modified with the amino-functional phosphate, AMPA. In a similar fashion, the reaction of P-H bonds residues with amines and aldehydes was also studied for the modification of reactive polymers. These ‘Kabachnik-Fields’ reactions were performed on small molecule model amines, commercially available amino-functional polymers and finally, a water-soluble succinimidyl-ester containing copolymer synthesised by ATRP.

Mestrado em Ciência de Materiais
Vertically aligned carbon nanotubes (VACNT) were synthesized using thermal chemical vapour deposition (CVD) technique and modified with oxygen-containing functional groups (hydroxyl, carbonyl and carboxyl) using an Ar:O2 (97:3) plasma. X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and scanning electron microscopy (SEM) have confirmed that those functional groups have been successfully grafted from the surface of the nanotubes. The plasma treatment was also found to remove significant amounts of amorphous carbon produced and deposited on the forests during the CVD process. The aligned carbon nanotube forests were further modified with an atom transfer radical polymerization (ATRP) initiator to grow poly(methyl methacrylate) (PMMA) chains via an in situ controlled/living radical polymerization. The resulting VACNT/PMMA composite was analyzed using Raman, Fourier transform infrared (FT-IR) and proton nuclear magnetic resonance (1H-NMR) spectroscopies, and scanning transmission electron microscopy (STEM). The TEM image mode and the 1H-NMR results clearly showed the presence of a polymer matrix surrounding the vertically aligned CNT forests. In addition, compressive tests carried out for both pristine VACNT and VACNT/PMMA composite have showed a higher compressive strength of the composite material than the pristine. This resulted from the denser structural arrangement of the vertically aligned CNTs due to the zipping effect observed for CNTs in solution processing methods and due to the presence of the polymer matrix, which gives extra support for the VACNTs.
Nanotubos de carbono alinhados verticalmente (VACNT) foram preparadas por deposição química em fase vapor (CVD) em parede quente e posteriormente submetidos a um tratamento com plasma de uma mistura Ar:O2 (97:3) de modo a obter grupos hidroxilo, carbonilo, carboxílo à superfície. Esta modificação superficial dos nanotubos foi confirmada através das espectroscopias de XPS e de Raman, bem como por microscopia electrónica de varrimento. Os resultados obtidos mostraram ainda que através do tratamento de plasma se remove uma quantidade significativa de material grafítico que fora depositado durante o processo CVD. Após o tratamento com plasma dos VACNT, procedeu-se ao ancoramentp do iniciador de polimerização radicalar por transferência e átomo (ATRP) à sua superfície. Seguidamente procedeu-se à preparação de cadeias de poli(metacrilato de metido) (PMMA) a partir da superfície. O compósito obtido VACNT/PMMA foi caracterizado pelas espectroscopias de Raman, de FT-IR e 1H-RMN e ainda por microscopia de transmissão electrónica em varrimento (STEM). Os resultados obtidos a partir de imagens em modo TEM e do RMN-1H confirmaram a presença da matriz polimérica em torno dos VACNT. Além disso, os testes de compressão realizados tanto para as florestas originais, como para o compósito, revelaram que este último apresentou uma resistência à compressão superior que resulta da compactação (zipping) sofrida pelos tubos durante o processamento em solução, bem como da presença da matriz polimérica a qual confere uma maior estabilidade dimensional e mecânica à floresta de CNTs.

Sono stati sintetizzati diversi copolimeri con struttura a blocchi o di tipo statistico aventi struttura e pesi medi molecolari controllati utilizzando polimerizzazioni radicaliche viventi (ATRP). Questi polimeri solitamente esibiscono proprietà superiori rispetto a polimeri con struttura non controllata e alta polidispersità. Alcuni dei polimeri sono stati ottenuti polimerizzando un monomero metacrilico sintetizzato tramite esterificazione di una miscela commerciale costituita da alcoli alifatici a diversa lunghezza di catena. Per fare ciò è stata studiata la polimerizzazione controllata di monomeri metacrilici a diverso peso molecolare, dimostrando che la reattività dipende dalla lunghezza della catena laterale. I nuovi copolimeri ottenuti sono stati caratterizzati tramite 1H-NMR, DSC, TGA, GPC ed IR.

The investigation into the encapsulation of gold nanoparticles (AuNPs) by poly(methyl methacrylate) (PMMA) was undertaken. This was performed by three polymerisation techniques including: grafting PMMA synthesised by reversible addition-fragmentation chain transfer (RAFT) polymerisation to AuNPs, grafting PMMA synthesised by atom transfer radical polymerisation (ATRP) from the surface of functionalised AuNPs and by encapsulation of AuNPs within PMMA latexes produced through photo-initiated oil-in-water (o/w) miniemulsion polymerisation. The grafting of RAFT PMMA to AuNPs was performed by the addition of the RAFT functionalised PMMA to citrate stabilised AuNPs. This was conducted with a range of PMMA of varying molecular weight distribution (MWD) as either the dithioester or thiol end-group functionalities. The RAFT PMMA polymers were characterised by gel permeation chromatography (GPC), ultraviolet-visible (UV-vis), Fourier transform infrared-attenuated total reflectance (FTIR-ATR), Fourier transform Raman (FT-Raman) and proton nuclear magnetic resonance (1H NMR) spectroscopies. The attachment of PMMA to AuNPs showed a tendency for AuNPs to associate with the PMMA structures formed, though significant aggregation occurred. Interestingly, thiol functionalised end-group PMMA showed very little aggregation of AuNPs. The spherical polymer-AuNP structures did not vary in size with variations in PMMA MWD. The PMMA-AuNP structures were characterised using scanning electron microscopy (SEM), transition electron microscopy (TEM), energy dispersive X-ray analysis (EDAX) and UV-vis spectroscopy. The surface confined ATRP grafting of PMMA from initiator functionalised AuNPs was polymerised in both homogeneous and heterogeneous media. 11,11’- dithiobis[1-(2-bromo-2-methylpropionyloxy)undecane] (DSBr) was used as the surface-confined initiator and was synthesised in a three step procedure from mercaptoundecanol (MUD). All compounds were characterised by 1H NMR, FTIR-ATR and Raman spectroscopies. The grafting in homogeneous media resulted in amorphous PMMA with significant AuNP aggregation. Individually grafted AuNPs were difficult to separate and characterise, though SEM, TEM, EDAX and UV-vis spectroscopy was used. The heterogeneous polymerisation did not produce grafted AuNPs as characterised by SEM and EDAX. The encapsulation of AuNPs within PMMA latexes through the process of photoinitiated miniemulsion polymerisation was successfully achieved. Initially, photoinitiated miniemulsion polymerisation was conducted as a viable low temperature method of miniemulsion initiation. This proved successful producing a stable PMMA with good conversion efficiency and narrow particle size distribution (PSD). This is the first report of such a system. The photo-initiated technique was further optimised and AuNPs were included into the miniemulsion. AuNP encapsulation was very effective, producing reproducible AuNP encapsulated PMMA latexes. Again, this is the first reported case of this. The latexes were characterised by TEM, SEM, GPC, gravimetric analysis and dynamic light scattering (DLS).

Este estudo descreve a obtenção e caracterização de bioblendas de PLLA/HIPS de diferentes composições, compatibilizadas por copolímero em bloco PS-b-PLA. Além de mistura via fundido a 180 e 210°C, uma nova estratégia de preparação de bioblendas PS/HIPS e PLLA foi desenvolvida via método in situ, através da polimerização de estireno na presença do PLA. O copolímero em bloco PS-b-PLA foi eficiente como compatibilizante interfacial e permitiu controle da morfologia em bioblendas de PLLA e HIPS em determinadas condições de mistura, fato comprovado por análises de microscopia eletrônica de transmissão e varredura. Copolímeros PS-b-PLA de diferentes composições foram obtidos a partir de PS com terminação hidroxila (OH-PS-Br) como macroiniciador da polimerização por abertura de anel de lactídeo. A rota inversa, empregando o PLA funcionalizado com 2,2,2 tribromoetanol (PLA-Br) como macroiniciador da ATRP do estireno, também se mostrou uma rota sintética eficiente para obtenção do copolímero. O OH-PS-Br foi sintetizado via polimerização radicalar por transferência de átomo (ATRP) convencional e via regeneração de ativadores por transferência de elétrons (ATRP-ARGET). A simplificação e aumento da taxa de reação da ATRP-ARGET do estireno foram explorados através da alteração das variáveis de reação. O aumento da temperatura de reação de 90°C para 100°C praticamente dobrou a taxa de polimerização do estireno. De forma controlada, a reação foi conduzida sob atmosfera oxidativa, sem purificação adicional para retirada do inibidor do estireno, e usando etilbenzeno como solvente.
This study describes the preparation and characterization of PLLA/HIPS bioblends of various compositions which were compatibilized by PS-b-PLA block copolymer. Bioblends were obtained by melt mixing at 180 and 210 °C, and also by a new way to prepare PLLA/HIPS compositions via in situ polymerization of styrene in the presence of PLA. The PS-b-PLA block copolymer was effective as a compatibilizer and allowed some control over PLLA/HIPS bioblends morphology in some mixing conditions, which was confirmed by transmission and scanning electron microscopy. PLA-b-PS copolymers of different compositions were obtained from hydroxyl-terminated PS (OH-PS-Br) as a macroinitiator for the ring opening polymerization of lactide. The reverse route using 2,2,2-tribromoethanol functionalized PLA (PLA-Br) as macroinitiator for ATRP of styrene also was an efficient synthetic strategy to obtain the copolymer. The OH-PS-Br was synthesized via conventional atom transfer radical polymerization (ATRP) and by activators regenerated by electron transfer (ATRP-ARGET). The influence of the main reaction parameters of the ATRPARGET of styrene was studied aiming for reaction rate increase and simplification. Increasing the reaction temperature from 90°C to 100°C almost doubled the rate of styrene polymerization. The reaction was also succesfully conducted under oxidative atmosphere, without additional purification for styrene inhibitor removal, and by using ethylbenzene as solvent.

This thesis describes the design and use of nanofillers (NFs) synthesized by surface-initiated atom transfer radical polymerization (SI-ATRP). The history of polymer/inorganic (hybrid) nanocomposites (NCs), the development and fundamentals of SI-ATRP are discussed in the introductory chapter. Chapters II and III present the major challenges in SI-ATRP, including the surface confinement effect that influences the polymerization kinetics and unavoidable termination reactions that limit the molecular weight of polymers tethered on surfaces. Chapter II discusses the experiments that demonstrate the surface confinement effects which were found to be a minor contributor to controlled chain growth in normal SI-ATRP, with one exception, when one attempts to polymerize sterically bulky and hydrophilic monomers. Chapter III discusses ways to suppress termination reactions that contribute to molecular weight limitations by carrying out the reactions under high-pressure, high-dilution, or/and at high-temperature. In addition to extend the fundamental understanding and improvements of SI-ATRP, Chapters IV and V discuss the use of NFs to create novel nanostructured functional materials. Chapter IV focuses on the preparation of traditional filler-matrix composites. Mechanically and thermally stable films with silica nanoparticle (SiO2) filler loadings up to 70 wt% were achieved by introducing enthalpy interactions to improve the dispersibility of SiO2 in a selected matrix. Chapter V presents approaches that allow preparation of a procesesable self-assembled film of hybrid NCs that do not require blending with a host matrix. This class of material was created by NF self-assembly and interparticle brush entanglement which provided uniform NF dispersion in a monolayer film with zero aggregation, as observed by transmission electron microscopy. Chapter VI, VII, and VIII further expands the scope of materials designed in Chapter IV and V. Chapter VI specifically studies the structure-properties relationship of the particle-brush composites and the confirmation that controls the polymer conformation and interface strength which are the keys for various enhanced properties. Chapter VII discusses the effects of thermal self-initiation of styrene (S) on the properties of particle-brush materials. Chapter VIII discusses the use of particle-brush hybrid particles to synthesize porous nanocarbons.

Whilst atom transfer radical polymerisation (ATRP) has been shown to be a robust and versatile technique for the creation of a wide range of polymers from many different initiators, there is relatively little previous research into the usage of initiators containing amide functionality. Low initiator efficiencies, often resulting in higher than predicted molecular weight parameters, and slow polymerisations with variable rates of reaction are generally reported when amide initiators have previously been used. Various reasons have been proposed in the literature for poor performance of amide initiators including; interactions of the catalytic system of ATRP and the amide bond in the initiator, the irreversible loss of catalyst activity, a rapid initiation causing an overabundance of radicals and poor initiator efficiencies. No suitable solution for these problems had been put forward and the poor performance observed was a major hindrance for any work with amide initiators. This work describes the development of a system that enabled the usage of novel amide initiators for the ATRP of oligo (ethylene glycol) methyl ether methacrylate (OEGMA) with high levels of success. The development of an ideal set of reactions conditions was shown to produce materials with low dispersities and molecular weight parameters in close agreement to theoretical values. Through the usage of UV-visible spectroscopy and quantum chemical calculations the reason for poor amide initiator performance was determined to be as a result of the high bond dissociation energy of the initiator's halide as a result of its proximity to the amide bond. This effect could be mitigated, but not eliminated, by performing reactions in polar solvent systems. Optimised reaction conditions were utilised in the synthesis of a block copolymer of POEGMA and polyethyleneimine, which shows potential as a stabiliser for superparamagnetic nanoparticles and as a controlled drug delivery system due to the materials high solubility and thermoresponsive properties.

A study of the atom transfer radical polymerisation (ATRP) of water-soluble, acidic, monomers was carried out in aqueous media. The ATRP of sodium methacrylate (MAANa) produced polymers with controlled molecular weights and narrow polydispersities (Me/M, - 1.3) at 90°C. This is the first reported example of direct polymerisation of an acidic monomer via ATRP. Previously, such acidic polymers were produced by polymerisation of protected monomers. In this thesis, copper(l) bromide and iron(II) bromide were investigated as ATRP catalysts. Both were found to be effective when solubilised by 2,2'-bipyridine (bipy). Monomer conversions between 75 and 85 % were obtained in the presence of Cu(l)Brlbipy, and conversions as high as 94 % were obtained in the presence of Fe(II)Br2Ibipy. Kinetic studies carried out on the ATRP of MAANa using the CuBrlbipy catalyst and an oligo(ethylene glycol)-based initiator indicated that polymerisation proceeded via first order kinetics with respect to monomer consumption, and that molecular weight increased linearly with conversion. This is as expected for a living polymerisation. At approximately 75 - 85 % conversion, however, premature termination occurred. Both bromine microanalyses and 'n and 13CNMR studies indicated that the halide-capped polymer chain-ends undergo HBr elimination. Low molecular weight « 10,000 g mol") MAANa homopolymers and oligo(ethylene glycol)-sodium methacrylate block copolymers (PEG-b-PMAANa) were examined as possible macro initiators for the ATRP of sodium 4-styrenesulfonate (SSNa), potassium 3- sulfopropyl methacrylate (SPMAK) and sodium allyl sulfonate (SAS). PEG-b-PMAANa was found to initiate the ATRP of SSNa, yielding a polymer with controlled molecular weight and a polydispersity of 1.23. Initiation of the ATRP of SPMAK and SAS was less successful. This was likely due to the loss of functionality of the MAANa-based polymers. Block copolymers were obtained, however, by macroinitiating the aqueous ATRP of MAANa using a monomethoxy-capped oligo(ethylene glycol) methacrylate homopolymer. Successful ATRP of MAANa was also achievable at ambient temperatures in the presence of a co-solvent, 2-(dimethylamino)ethanol, DMAE. DMAE appears to dramatically increase the rate of polymerisation whilst still maintaining control when used in equimolar quantities (relative to the monomer). Polymers with predetermined molecular weights and narrow polydispersities were produced in good yield (up to 86 % conversion) within five minutes at 20°C. The ATRP of other hydrophilic monomers was also investigated, albeit in less detail. These monomers included sodium acrylate, mono-2-(methacryloyloxy)ethyl succinate, 2- hydroxyethyl acrylate, itaconic acid, and 2-acrylamido-2-methyl-propanesulfonic acid. Generally less control was achieved for such syntheses than for the ATRP of MAANa.

Orientador: Valdemiro Pereira de Carvalho Júnior
Banca: André Luiz Bogado
Banca: Ana Maria Pires
Resumo: A investigação de sistemas catalíticos duais capazes de mediar as reações de polimerização por abertura de anel via metátese (ROMP) e de polimerização radicalar por transferência de átomo (ATRP) simultaneamente é de grande interesse e importância na obtenção de novos materiais com potencial de aplicação. Neste estudo, novos complexos de Rutênio(II) coordenados a diferentes carbenos N-heterocíclicos derivados de cicloalquilaminas (ciclopentil (IPent) (1a), ciclohexil (IHex) (1b), cicloheptil (IHept) (1c) e ciclooctil (IOct) (1d)) foram sintetizados: [RuCl2(S-dmso)2(IPent)] (2a), [RuCl2(S-dmso)2(IHex)] (2b), [RuCl2(S-dmso)2(IHept)] (2c) e [RuCl2(S-dmso)2(IOct)] (2d). Os sais imidazólicos e seus respectivos complexos de rutênio foram caracterizados por FTIR, UV-Vis, RMN e voltametria cíclica, comprovando-se o sucesso na síntese dos mesmos. Os complexos planejados foram avaliados como precursores catalíticos em reações de ROMP de norborneno (NBE) e em reações de ATRP de metacrilato de metila (MMA). As sínteses de polinorborneno (poliNBE) via ROMP com os complexos 2a-d como pré-catalisadores foram avaliadas sob condições de reação ([EDA]/[Ru] = 28 (5 µL), [NBE]/[Ru] = 5000, temperatura de 50 ºC, utilizando clorofórmio como solvente, variando o tempo até 60 minutos. A polimerização de MMA via ATRP foi conduzida usando os complexos 2a-d na presença de etil-α-bromoisobutirato (EBiB) como iniciador. Os testes catalíticos foram avaliados em função do tempo de reação usando a razão...
Abstract: The investigation of dual catalytic systems able to mediate simultaneously ring-opening metathesis polymerization (ROMP) and atom-transfer radical polymerization (ATRP) reactions is of great interest and importance in obtaining new materials with potential for application. In the study, new complexes of Ruthenium (II) coordinated to different N-heterocyclic carbenes derived from cycloalkylamines (cyclopentyl (IPent) (1a), cyclohexyl (IHex) (1b), cycloheptyl (IHept) (1c) and cyclooctyl (IOct) (1d), [RuCl2(S-dmso)2(IHept)] (2a), [RuCl2(S-dmso)2(IHex)] (2b) [RuCl2(S-dmso)2(IHept)] (2c) and [RuCl2(S-dmso)2(IOct)] (2d). The imidazole salts and their respective ruthenium complexes were characterized by FTIR, UV-Vis, NMR and cyclic voltammetry, proving the success in their synthesis. The planned complexes were evaluated as catalytic precursors in norbornene ROMP (NBE) reactions and in methyl methacrylate (MMA) ATRP reactions. The polynorbornene (polyNBE) syntheses via ROMP with complexes 2a-d as pre-catalysts were evaluated under reaction conditions ([EDA] / [Ru] = 28 (5 μL), [NBE] / [Ru] = 5000, The polymerization of MMA via ATRP was conducted using the complexes 2a-d in the presence of ethyl α-bromoisobutyrate (EBiB) as the initiator.The catalytic tests were evaluated As a function of the reaction time using the molar ratio [MMA] / [EBiB] / [Ru] = 1000/2/1. All ATRP experiments were conducted at 85 °C. The linear correlation of ln ([MMA]0 / [MMA]) as a function of time in MMA ATRP...
Mestre

Negli ultimi anni i copolimeri a blocchi hanno acquistato sempre maggiore interesse sia da un punto di vista accademico che industriale grazie alle loro potenziali applicazioni come membrane per la separazione di gas, come compatibilizzanti di miscele polimeriche e nel campo del nanopatterning. Il Bisfenolo A policarbonato (PC) ed il polimetilmetacrilato (PMMA) rappresentano importanti tecnopolimeri e trovano impiego in svariati campi di applicazione quali: ottico, automobilistico, elettronico, arredamento e costruzioni per questo motivo risulta auspicabile l'ottenimento di copolimeri a blocchi PC/PMMA. E' stato sintetizzato il prepolimero (PC-2OH) terminato con gruppi bis-fenolici ad entrambi i lati della catena, il quale e' stato funzionalizzato mediante 2-bromoisobutiril bromuro e a-clorofenilacetil cloruro al fine di ottenere i macroiniziatori PCBr e PCCl. I macroinizatori sono stati poi utilizzati per la sintesi di copolimeri a blocchi PMMA-b-PC-b-PMMA mediante Polimerizzazione Radicalica Vivente. Sono stati sintetizzati tre copolimeri a rapporti molari PC/MMA diversi: (1:1000), (1:500), (1:100). Il prepolimero, i macroiniziatori, ed i copolimeri ottenuti sono stati caratterizzati mediante NMR,SEC, DSC, TGA e MALDI-TOF, AFM e SEM. I risultati prodotti da questo lavoro di ricerca hanno permesso di ottimizzare i parametri di reazione sia per la sintesi del PC-2OH che dei macroiniziatori e di sintetizzare e caratterizzare copolimeri di e triblocco mediante ATRP in merito ai quali ad oggi non sono presenti molti riferimenti bibliografici.
During the last decades block copolymers have gained more interest from both academic and industrial point of view because of their potential applications as membranes for gas separation, as compatibilizers in polymer blends and for nano-patterning. Bisphenol A polycarbonate (PC) and polymethylmethacrylate (PMMA) are important engineering plastics used in several applications such as optical, automotive, electronics, furniture and construction. Considering their properties it is advantageous to obtain block copolymers of PC/PMMA. It was synthesized prepolymer (PC-2OH) terminated with bis-phenol groups at both ends of the chain, which has been functionalized by 2-bromoisobutiril bromide and a-clorofenilacetil chloride in order to obtain the macroiniziators PCBr and PCCl. These macroinizators were then used for the synthesis of block copolymers PMMA-b-PC-b-PMMA by Living Radical Polymerization (ATRP). Three copolymers were synthesized in different (1:1000) (1:500) (1:100) molar ratios of PC/MMA. The prepolymer, the macroiniziators, and the copolymers obtained were characterized by NMR, SEC, DSC, TGA,MALDI-TOF, AFM and SEM. The results of this research have allowed us to optimize the reaction parameters for both the synthesis of PC-2OH and the macroiniziators and to synthesize and characterize di- and tri-block copolymers.

L’objectif était de développer et d’utiliser des nanoparticules hybrides de type«coeur-écorce» composées d’un coeur de silice dense entouré par des chaînes polymères fonctionnalisées par des ligands d’ATRP comme support catalytique pour la polymérisation du MMA par ATRP. Deux stratégies de synthèse de nanoparticules hybrides ont été élaborées. La première a consisté à immobiliser sur un support de silice, d’une manière covalente, des chaînes fonctionnelles synthétisées par NMP comportant des ligands capables de complexer le bromure de cuivre. Des nanoparticules de SiO2@polymère fonctionnel ayant de faibles densités de greffage en polymère ont été ciblées afin d’éviter leur recouvrement sur la surface. Cependant, les polymérisations n’étaient pas contrôlées probablement à cause d’un manque d’accessibilité de l’amorceur et des radicaux propageants aux complexes decuivre. Afin de rendre les catalyseurs supportés plus accessibles en solution, nous avons élaboré une seconde stratégie basée sur un système catalytique hybride réversible. Il consiste à immobiliser des chaînes α-fonctionnalisées par un motif donneur-accepteur de proton(DAD) via des liaisons hydrogène sur des particules de silice modifiées par un motif complémentaire (ADA). Des PMMA de masses molaires contrôlées ont été synthétisés avec des dispersités plus faibles que celles obtenues en ATRP homogène (en présence des chaînes libres). Après séparation du catalyseur du milieu réactionnel par centrifugation, nous avons montré qu’avec un excès du motif ADA, 96% du cuivre initialement introduit ont été récupérés
The aim of this project is to develop hybrid nanoparticles bearing well definedpolymer arms as supported catalyst for the atom transfer radical polymerization of methylmethacrylate. This new generation of “semi heterogeneous" catalysts was prepared by twostrategies. The first consisted of immobilizing the polymer arms bearing the ligands enablingcoordination of copper bromide onto silica particles by covalent bonds. Hybrid nanoparticleswith low polymer grafting density were targeted to prevent the overlapping of chains on thesurface. Unfortunately, the polymerizations were not controlled probably due to a lack ofaccessibility of the initiator and propagating radicals to the copper complexes. To improve theaccessibility, a reversibly supported catalyst was developed via self-assembly using hydrogenbonding between chains α-functionalized by a proton donor-acceptor unit (DAD) and acomplementary unit (ADA) anchored on silica particles. These new hybrid materials wereefficient in the controlled radical polymerization of MMA, yielding polymers with controlledmolecular weights and dispersities narrower than those obtained for homogeneous ATRP.Moreover, after catalyst separation from the reaction medium by centrifugation, more than96% of the originally used copper was recovered

Kommerziell erhältliche Ionenaustauscher basieren häufig auf funktionalisierten Cellulosemembranen, die mit CerIV und Glycidylmethacrylat (GMA) gepfropft und anschließend sulfoniert werden.  Die Untersuchung dieser Polymerisation zeigte, dass während der Pfropfung eine Vernetzung des Polymers über die Epoxidfunktion des Monomers auftritt. Daher konnte keine direkte Analyse des entstandenen Hydrogels durchgeführt werden und es wurde stattdessen Methylmethacrylat (MMA) auf der Oberfläche polymerisiert. Nach Entwicklung eines geeigneten Verfahrens zur Zersetzung der Membranen und Isolierung des Pfropfpolymers konnte dieses mit Gel-Permeations-Chromatographie (GPC) analysiert werden. Zusätzlich wurden Polymerisationen auf nicht-porösem Cellophan durchgeführt und die erhaltenen Proben mittels Rasterkraftmikroskopie (Atomic Force Microscopy, AFM) untersucht.  Die Ergebnisse zeigen, dass das gepfropfte PMMA einen Polymerisationsgrad von 2100 und eine Dichte von 0,45 Ketten pro nm2 auf der Oberfläche hat. Wird die gleiche Anzahl an Polymeren auch für Pfropfung mit PGMA angenommen und mit dem Pfropfgrad verglichen, ergibt sich damit unter Vernachlässigung der Vernetzung ein Polymerisationsgrad von etwa 800. Es konnte gezeigt werden, dass die für die Pfropfung verwendete Emulsion unter anderem aus Tröpfchen besteht, deren Größe mit der der Poren der Membran übereinstimmt. Dennoch treten bei der Polymerisation keine Ausschlusseffekte auf und die Größenverteilung der Emulsionspartikel stellt sich auch nach Filtration zügig wieder ein. Zusätzlich wurde eine Methode der Atom-Transfer radikalischen Polymerisation (ATRP) auf mikroporösen Membranen entwickelt und eingesetzt, um gezielt bestimmte Eigenschaften des Hydrogels zu variieren. Bei Versuchen mit MMA wurde der reversibel deaktivierte Charakter unter den verwendeten Bedingungen untersucht und nachgewiesen.  Die verwendete Methode erlaubt, die Kettenanzahl und –länge separat voneinander einzustellen, sodass der Einfluss dieser Größen auf die Eigenschaften des resultierenden Membranadsorbers gezielt untersucht werden konnte. Es zeigte sich, dass die Dichte der Ketten einen komplexen Einfluss sowohl auf die Permeabilität als auch auf die Bindungskapazität des Ionentauschers hat. Der Einfluss der Kettenlänge ist dagegen weniger subtil und entspricht den Erwartungen.  Aus den gewonnenen Daten wurde ein Modell für die Bindung von Proteinen an der gepfropften Oberfläche des Austauschers entwickelt und daraus die Kettenlänge und –dichte des Hydrogels abgeschätzt und mit alternativen Methoden verglichen.

Functional nanoparticles have garnered considerable attention due to their intriguing physical properties at the nanoscale for a broad range of applications, such as photocatalysis, capacitive energy storage, thermoelectric power generation, solar energy harvesting, flexible and transparent electronics, drug delivery, biomolecular electronics, and analytic chemistry, etc. Successful synthesis of nanoparticles and precise control over their shapes are critical to achieving desired functions. In the first part of my thesis, an effective synthetic route to plain nanoparticles is briefly introduced. Based on this general route, the synthesis of solid iron oxide nanoparticles and a slightly modified synthetic method of solid silica nanoparticles are presented in detail. In the second part of my thesis, simulation of optical absorption spectra and plasmonic near-field maps of gold nanoparticle and gold/titanium oxide nanoparticle are explored, and the effectiveness of simulation in predicting, optimizing, and guiding experimental design is emphasized.

The research project aimed to synthesise semiconducting polymer brushes (polymer chains densely grafted to a surface) utilising simple and efficient organic chemistry methods, with a view to use in molecular-level electronic applications. Conjugated polymers were initially chosen for their ability to conduct electrical charge along a polymer chain by facilitating electron transfer between π-bonds. Polymers also aimed to be living , which could allow for further chain growth at a later point in time. This could lead to the production of various useful brush block co-polymers, with different blocks (or layers) of polymers having different chemical, structural and electronic properties. Initially, several syntheses towards monomers for poly(phenyl isocyanide) and poly(quinoxaline-2,3-diyl) were undertaken with limited success. Attention was turned to the synthesis of poly(thiophene)s by Kumada catalyst-transfer polymerisation (KCTP), again with varying success. After this, ring-opening metathesis polymerisation (ROMP) was explored as a possible avenue. The successful synthesis of several cyclopropenes for use as monomers was carried out. However, the ROMP of these monomers failed. ROMP of unsubstituted norbornene was successful. XPS studies suggested that vapour deposition of SAMs (Self Assembled Monolayers) gave homogenous monolayers. Solution-phase depositions appeared prone to inhomogeneous multilayer deposition. Vapour deposited SAMs gave better grafting densities at lower deposition pressures, leading to thicker polymer brushes. Finally, atom transfer radical polymerisation (ATRP) methods have been investigated. ARGET-ATRP was determined as the favoured method as it uses lower quantities of copper. Functionalised monomers for ATRP were synthesised, but homopolymers of these polyaromatic monomers have been difficult to synthesise by both copper-mediated ATRP and AIBN initiation. Polymer brushes and polymer brush diblocks of post-polymerisation modified PHEMA and PDMAEMA have been successfully grown on silicon wafers and glass slides, with a view to using the diblocks of these polymers as effective bulk heterojunction photovoltaic devices. The kinetics of the growth of both polymers by the ARGET and ATRP methods were studied to determine the degree to which each polymerisation is living; to determine if diblock growth would be possible. PHEMA brushes were successfully modified with a range of polyaromatic acid chlorides. Focussing on anthracene (which has excellent fluorescence properties, displaying a clear ability to move electrons between energy levels), this attachment was further confirmed by a range of techniques, before successfully growing a brush diblock of the unfunctionalised and functionalised polymers.

Azopolímeros apresentam propriedades de fotoisomerização, úteis para confecção de memórias ópticas, que dependem da arquitetura molecular do azopolímero e do filme formado a partir dele. Neste trabalho foram sintetizados polímeros com arquitetura molecular controlada, usando os azomonômeros [4-(N-etil-N-2-(metacriloxietil)) amino-2\'-cloro-4\'-nitroazobenzeno] (DR13MA) e [4-(N-etil-N-2-(metacriloxietil)) aminoazobenzeno] (MAEAMA). Para a síntese de homopolímeros e copolímeros em bloco foram utilizados dois métodos: NMRP - polimerização radicalar mediada por nitróxidos e ATRP - polimerização radicalar por transferência de átomo. Foram produzidos copolímeros dibloco, com um dos blocos contendo azocorantes, pela reação do monômero DR13MA com macroiniciadores poliestireno (PS) no método NMRP, e poli(metacrilato de metila) (PMMA) via ATRP. Homopolímeros de ambos os azomonômeros foram sintetizados por ATRP, e assim como os copolímeros em bloco mostraram cadeias com baixa polidispersividade. Complementando o trabalho de síntese, foram estudadas as propriedades dos materiais na interface ar-água, utilizando filmes de Langmuir, e procedeu-se a transferência dos mesmos para substratos sólidos formando filmes Langmuir-Blodgett (LB). Nos filmes de Langmuir foi observada a conformação e as interações (agregação) das moléculas dos materiais, destacadamente, no caso do homopolímero HPMAEA, foi observado um patamar próximo a 8 mN/m na isoterma de pressão de superfície, indicando haver reorganização do material no filme. Os filmes LB serviram como objeto de estudo das propriedades ópticas dos compostos, e no caso do homopolímero HPDR13 sintetizado via ATRP, pela primeira vez foi possível a realização de medidas em filmes puros do material. Medidas de armazenamento óptico foram realizadas para comprovar a aplicabilidade dos materiais em memórias ópticas. No caso do terpolímero PS-b-[MMA-co-DR13] sintetizado por NMRP, os resultados de armazenamento foram semelhantes aos obtidos com blendas. Para o homopolímero HPMAEA, uma grande influência do tipo de filme empregado (cast ou LB) foi observada no tempo de escrita das memórias, com o tempo para o filme LB sendo 26 vezes menor. Copolímeros em bloco PMMA-b-DR13 podem ser vantajosos por aliarem as propriedades ópticas do homopolímero HPDR13 à maior estabilidade térmica e mecânica do PMMA.
Azopolymers display photoisomerization properties, which can be exploited in optical memories, and depend strongly on the molecular architecture of the polymer chain and kind of film employed. In this work, azopolymers with controlled molecular architecture were synthesized using the azomonomers [4-(N-ethyl-N-2(methacryloxyethyl))amino-2\'-chloro-4\'-nitroazobenzene](DR13MA)and[4-(N-ethyl-N-2-(methacryloxyethyl))aminoazobenzene] (MAEAMA). Two methods were used to synthesize homopolymers and block-copolymers: NMRP - Nitroxide-mediated radical polymerization and ATRP - Atom transfer radical polymerization. Diblock-copolymers were produced, with one block composed by azodyes units, by reacting the monomer DR13MA with a polystyrene (PS) macroinitiator via NMRP, or with poly(methyl methacrylate) (PMMA) macroinitiator via ATRP. Homopolymers of both azomonomers were synthesized by ATRP, and - analogously to the blockcopolymers - exhibited controlled structure with a small polydispersity. The synthesized polymers were then used in the formation of Langmuir films at the air-water interface, which could be transferred onto solid substrates forming Langmuir-Blodgett (LB) films. In Langmuir films, an investigation was made of the conformation and interactions (aggregation) of the film-forming molecules. Interestingly, a plateau was observed at 8 mN/m in the surface pressure isotherm for the HPMAEA homopolymer, pointing to a reorganization of the polymer during compression. For HPDR13 produced by ATRP, it was possible to deposit LB films with no need to use surfactants, unlike the case of HPDR13 synthesized by conventional methods. Optical storage measurements were performed to demonstrate the applicability of the azo-containing materials in optical memories. For the terpolymer PS-b-[MMA-co-DR13] made by NMRP, the storage results were similar to those obtained with blends. In the case of the homopolymer HPMAEA, a large influence of the kind of film used (cast or LB) was observed in the writing time of the memories, with the writing time for the LB film being 26 times faster. PMMA-b-DR13 block-copolymers may be advantageous in combining the optical properties of the homopolymer HPDR13 with the thermal and mechanical stability of PMMA.

Des nouvelles particules hybrides de type silice@polymère fonctionnel ont été synthétisées pour la catalyse semi-hétérogène en polymérisation radicalaire contrôlée par transfert d’atome (ATRP). La copolymérisation du styrène et du chlorométhylstyrène par polymérisation radicalaire contrôlée par les nitroxydes a permis d’obtenir des chaînes pouvant être facilement post-modifiées par la 2-dipicolylamine, un ligand azoté capable de complexer certains métaux utilisés en ATRP. Ce copolymère s’est avéré efficace comme support de catalyseur lors de la polymérisation du styrène ou du méthacrylate de méthyle par ATRP. A l’inverse, les mêmes chaînes immobilisées par grafting onto sur des particules Stöber ne conduisent pas à une polymérisation contrôlée. Ces résultats sont très probablement dus à un manque d’accessibilité au catalyseur. L’introduction d’un noyau d’oxyde de fer au cœur des particules hybrides a également été effectuée et devrait permettre d’isoler plus facilement les objets du milieu par séparation magnétique en fin de réaction

Dans cette thèse, la fonctionnalisation de surface de nanocristaux de cellulose (NCC) par estérification et polymérisation ATRP a été envisagée, dans le but de développer de nouveaux matériaux avancés. Une méthode pratique permettant de caractériser les polymères greffés en surface des NCC a d’abords été développée, à partir des analyses DLS, DSC et TGA. L’efficacité des méthodes SI-ATRP et SI-ARGET ATRP pour initier le greffage de polystyrène (PS) ou poly(4-vinylpyridine) (P4VP) à la surface des NCC a ensuite été comparée. Les nano-hybrides P4VP-g-NCC pH-responsifs, ont alors été utilisés pour stabiliser des nanoparticules d’or (AuNPs), dans le but de produire des catalyseurs recyclables. L’activité catalytique des matériaux Au@P4VP-g-CNC obtenus – testée avec la réduction du 4-nitrophenol – a été améliorée de manière significative par rapport aux AuNPs seuls. Des polymères UV-responsifs de poly(cinnamoyloxy ethyl methacrylate) (PCEM) ont également été greffés à la surface des NCC, pour produire des particules UV-absorbantes. Les nano-hybrides PCEM-g-CNC obtenus se sont avérés efficaces comme stabilisants UV/thermiques et agents de renforts dans les films PVC. Finalement, une méthode facile pour préparer des colloidosomes à partir d’émulsions de Pickering inverses stabilisées par des NCC modifiés par des groupes cinnamates a été proposée. Des colloidosomes aux parois robustes et permettant un relargage lent de molécules encapsulées comme la rhodamine B ou l’acide désoxyribonucléique fluorescent ont alors été obtenus
In this thesis, the surface functionalization of cellulose nanocrystals (CNC) by esterification and ATRP reactions was envisaged, with the objective to develop novel advanced materials. A convenient method to characterize the polymers grafted on CNC by Si-ATRP has been first developed, based on DLS, DSC and TGA analyses. The efficiency of the SI-ATRP and SI-ARGET ATRP methods to initiate the grating of polystyrene (PS) or poly(4-vinylpyridine) (P4VP) at the CNC surface were then compared. The pH-responsive P4VP-g-CNC nano-hybrids were subsequently utilized to stabilize gold nanoparticles (AuNPs), in view of producing recyclable catalysts. The catalytic activity of the Au@P4VP-g-CNC material – tested with the reduction of 4-nitrophenol – was significantly improved compared with single AuNPs. UV-responsive poly(cinnamoyloxy ethyl methacrylate) (PCEM) polymers were also grafted on CNC, to produce particles with UV absorbing properties. The PCEM-g-CNC nano-hybrids obtained turned out to be efficient UV/thermal stabilizers and reinforcing agents in PVC films. Finally, a facile method to prepare colloidosomes from w/o inverse Pickering emulsions stabilized by cinnamate-modified CNC was proposed. Colloidosomes with robust shells and allowing the slow release of encapsulated molecules such as rhodamine B or fluorescent deoxyribonucleic acid were then obtained

Les travaux présentés dans ce manuscrit ont porté sur l'élaboration de nouveaux copolymères dibloc amphiphiles (poly(ε-caprolactone)-b-poly(méthacrylate d'oligo(éthylène glycol) méthyl éther) biodégradables, thermostimulables et susceptibles d'être employés dans des applications respectueuses de l'environnement comme le traitement des eaux contaminées. La particularité de ces copolymères provient d'une part de la différence de solubilité des deux blocs et d'autre part de l'association d'un bloc hydrophobe biodégradable à un bloc thermostimulable hydrophile. Les propriétés de ces copolymères en milieu aqueux ont ainsi été évaluées en fonction de la température. Ces composés ont été obtenus par la combinaison de deux techniques de polymérisation contrôlée en utilisant un amorceur difonctionnel. Pour cela, deux stratégies ont été testées : i) la polymérisation par ouverture de cycle (POC) de l'ε-caprolactone à partir d'un macro-amorceur de poly(méthacrylate d'oligo(éthylène glycol) méthyl éther) à terminaison OH après avoir mis au point les conditions expérimentales de la POC en comparant plusieurs catalyseurs. ii) par polymérisation radicalaire par transfert d'atome (ATRP) du méthacrylate d'oligo(éthylène glycol) amorcée à partir d'une poly(ε-caprolactone) à extrémité bromée. Les températures critiques inférieures de solubilité (LCST) de ces copolymères ont été déterminées par UV visible. Leurs comportements micellaires ont été étudiés par mesures HPPS
The development of new biodegradable diblock copolymers poly(ε-caprolactone)-b-poly[oligo(ethylene glycol)methyl ether methacrylate], which could be used in environmental friendly applications such as treatment of contaminated water has been the main goal of this work. For the preparation these copolymers, the ring-opening polymerization (ROP) and the Atom Transfer Radical Polymerization (ATRP) were combined by using a bifunctional initiator. The two-step route for the synthesis of these copolymers was using either ATRP or ROP as first step and the other polymerization secondly. Each polymerization was studied carefully in order to control the macromolecular parameters of the copolymers. On the one hand, the ATRP of methacrylates bearing oligo(ethylene glycol) was carried out by using poly(ε-caprolactone) with bromide end-group as macroinitiator. On the other hand, the ring opening polymerization of ε-caprolactone was initiated by the hydroxyl end-group of the poly[oligo(ethylene glycol)methyl ether methacrylate], using tin octoate, tin tetrakis(phenylethynyl) or bismuth triflate as catalysts. The Low Critical Solution Temperature (LCST) of these amphiphilic diblock copolymers in aqueous medium have been determined by UV-visible spectroscopy. Their micellar behaviors were also studied by measuring size by HPPS

Von der Natur geschaffene Polymere faszinieren Polymerforscher durch ihre spezielle auf eine bestimmte Aufgabe ausgerichtete Funktionalität. Diese ergibt sich aus ihrer Bausteinabfolge uber die Ausbildung von Uberstrukturen. Dazu zählen zum Beispiel Proteine (Eiweiße), aus deren Gestalt sich wichtige Eigenschaften ergeben. Diese Struktureigenschaftsbeziehung gilt ebenso für funktionelle synthetische Makromoleküle. Demzufolge kann die Kontrolle der Monomersequenz in Polymeren bedeutend für die resultierende Form des Polymermoleküls sein. Obwohl die Synthese von synthetischen Polymeren mit der Komplexität und der Größe von Proteinen in absehbarer Zeit wahrscheinlich nicht gelingen wird, können wir von der Natur lernen, um neuartige Polymermaterialien mit definierten Strukturen (Sequenzen) zu synthetisieren. Deshalb ist die Entwicklung neuer und besserer Techniken zur Strukturkontrolle von großem Interesse für die Synthese von Makromolekülen, die perfekt auf ihre Funktion zugeschnitten sind. Im Gegensatz zu der Anzahl fortgeschrittener Synthesestrategien zum Design aus- gefallener Polymerarchitekturen – wie zum Beispiel Sterne oder baumartige Polymere (Dendrimere) – gibt es vergleichsweise wenig Ansätze zur echten Sequenzkontrolle in synthetischen Polymeren. Diese Arbeit stellt zwei unterschiedliche Techniken vor, mit denen die Monomersequenz innerhalb eines Polymers kontrolliert werden kann. Gerade bei den großtechnisch bedeutsamen radikalischen Polymerisationen ist die Sequenzkontrolle schwierig, weil die chemischen Bausteine (Monomere) sehr reaktiv sind. Im ersten Teil dieser Arbeit werden die Eigenschaften zweier Monomere (Styrol und N-substituiertes Maleinimid) geschickt ausgenutzt, um in eine Styrolkette definierte und lokal scharf abgegrenzte Funktionssequenzen einzubauen. Uber eine kontrollierte radikalische Polymerisationsmethode (ATRP) wurden in einer Ein-Topf-Synthese über das N-substituierte Maleinimid chemische Funktionen an einer beliebigen Stelle der Polystyrolkette eingebaut. Es gelang ebenfalls, vier unterschiedliche Funktionen in einer vorgegebenen Sequenz in die Polymerkette einzubauen. Diese Technik wurde an zwanzig verschiedenen N-substituierten Maleinimiden getestet, die meisten konnten erfolgreich in die Polymerkette integriert werden. In dem zweiten in dieser Arbeit vorgestellten Ansatz zur Sequenzkontrolle, wurde der schrittweise Aufbau eines Oligomers aus hydrophoben und hydrophilen Segmenten (ω-Alkin-Carbonsäure bzw. α-Amin-ω-Azid-Oligoethylenglycol) an einem löslichen Polymerträger durchgeführt. Das Oligomer konnte durch die geschickte Auswahl der Verknüpfungsreaktionen ohne Schutzgruppenstrategie synthetisiert werden. Der lösliche Polymerträger aus Polystyrol wurde mittels ATRP selbst synthetisiert. Dazu wurde ein Startreagenz (Initiator) entwickelt, das in der Mitte einen säurelabilen Linker, auf der einen Seite die initiierende Einheit und auf der anderen die Ankergruppe für die Anbindung des ersten Segments trägt. Der lösliche Polymerträger ermöglichte einerseits die schrittweise Synthese in Lösung. Andererseits konnten überschüssige Reagenzien und Nebenprodukte zwischen den Reaktionsschritten durch Fällung in einem Nicht-Lösungsmittel einfach abgetrennt werden. Der Linker ermöglichte die Abtrennung des Oligomers aus jeweils drei hydrophoben und hydrophilen Einheiten nach der Synthese.
Polymer scientists are impressed by polymers created by nature. This is caused by their structure which is aimed to fulfill very special functions. The structure is primary built by sequential covalent linking of building units. Secondly, supramolecular aggregation leads to three-dimensional alignment. The sequence of the building blocks has a high influence on the higher molecular arrangement. Proteins are only one example for supramolecular structures which have special functions because of their supramolecular arrangement. This structure-property relationship is also possible for synthetic polymers. For this reason the control of monomer sequences in synthtic polymers is just as important for the resulting structure of a synthetic polymer molecule. Even though the synthesis of polymers with complex strucures and sizes as in nature is impossible in near future. But the development of new and better techniques for sequence control in synthetic polymers is of high importance to create well defined macromolecular structures which are tailor-made for their function. In contrast to a lot of advanced synthethis strategies for the design of complex polymer architechtures (e.g. brushes, stars, or dendrimers) their are less approaches for a monomer sequence control in synthetic polymers. This work presents two different techniques for controlling the monomer sequence inside a polymer. Especially in technologically significant radical polymerization it is difficult to control the monomer sequence because radical species are very reactive and the addition of a monomer to the radical function is not selective. The first approach makes use of the properties of two monomers (styrene and N-substituted maleimides) to add chemical funtions locally inside a polystyrene chain. By addition of N-functionalized maleimides during the polymerization of styrene chemical functions could be added at any desired position inside the polystyrene chain. This technique was tested on 20 different N-substituted maleimides. Most of them were incorporated successfully into the polymer chain. The second monomer sequence control approach is a stepwise synthesis of an oligomer made of short alternating hydrophobic and hydrophilic segments on a soluble polymer support. Two building blocks were used: ω-alkyne carboxylic acid (A-B) and α-amine-ω-azide oligoethylene glycol (C-D). The linking of the segments was done by applying two very efficient chemical reactions, namely 1,3-dipolar cycloaddition of terminal alkynes (A) and azides (D) and amidification of carboxylic acids (B) with primary amines (C). These two reactions proceed chemoselectively in an ABCD multifunctional mixture without a protection chemistry strategy. The polystyrene support was synthesized by atom transfer radical polymerization (ATRP) in the presence of an azido-functionalized ATRP initiator containing a labile p-alkoxybenzyl ester linker. Depending on the choise of solvent, the soluble polymer support was used in solution during the coupling reactions or was precipitated for an easy removal of excessive reagents and by-products. The acid-labile linker could be cleaved by trifluoroacetic acid treatment to obtain a hydrophilic/hydrophobic block copolymer.

L’objectif était de développer et d’utiliser des nanoparticules hybrides de type«coeur-écorce» composées d’un coeur de silice dense entouré par des chaînes polymères fonctionnalisées par des ligands d’ATRP comme support catalytique pour la polymérisation du MMA par ATRP. Deux stratégies de synthèse de nanoparticules hybrides ont été élaborées. La première a consisté à immobiliser sur un support de silice, d’une manière covalente, des chaînes fonctionnelles synthétisées par NMP comportant des ligands capables de complexer le bromure de cuivre. Des nanoparticules de SiO2@polymère fonctionnel ayant de faibles densités de greffage en polymère ont été ciblées afin d’éviter leur recouvrement sur la surface. Cependant, les polymérisations n’étaient pas contrôlées probablement à cause d’un manque d’accessibilité de l’amorceur et des radicaux propageants aux complexes decuivre. Afin de rendre les catalyseurs supportés plus accessibles en solution, nous avons élaboré une seconde stratégie basée sur un système catalytique hybride réversible. Il consiste à immobiliser des chaînes α-fonctionnalisées par un motif donneur-accepteur de proton(DAD) via des liaisons hydrogène sur des particules de silice modifiées par un motif complémentaire (ADA). Des PMMA de masses molaires contrôlées ont été synthétisés avec des dispersités plus faibles que celles obtenues en ATRP homogène (en présence des chaînes libres). Après séparation du catalyseur du milieu réactionnel par centrifugation, nous avons montré qu’avec un excès du motif ADA, 96% du cuivre initialement introduit ont été récupérés
The aim of this project is to develop hybrid nanoparticles bearing well definedpolymer arms as supported catalyst for the atom transfer radical polymerization of methylmethacrylate. This new generation of “semi heterogeneous" catalysts was prepared by twostrategies. The first consisted of immobilizing the polymer arms bearing the ligands enablingcoordination of copper bromide onto silica particles by covalent bonds. Hybrid nanoparticleswith low polymer grafting density were targeted to prevent the overlapping of chains on thesurface. Unfortunately, the polymerizations were not controlled probably due to a lack ofaccessibility of the initiator and propagating radicals to the copper complexes. To improve theaccessibility, a reversibly supported catalyst was developed via self-assembly using hydrogenbonding between chains α-functionalized by a proton donor-acceptor unit (DAD) and acomplementary unit (ADA) anchored on silica particles. These new hybrid materials wereefficient in the controlled radical polymerization of MMA, yielding polymers with controlledmolecular weights and dispersities narrower than those obtained for homogeneous ATRP.Moreover, after catalyst separation from the reaction medium by centrifugation, more than96% of the originally used copper was recovered

The use of living radical polymerization methods has shown significant potential to control grafting of polymers from inert polymeric substrates. The objective of this thesis is to create advanced substrates for use in combinatorial chemistry applications through the use of g-radiation as a radical source, and the use of RAFT, ATRP and RATRP living radical techniques to control grafting polymerization. The substrates grafted were polypropylene SynPhase lanterns from Mimotopes and are intended to be used as supports for combinatorial chemistry. ATRP was used to graft polymers to SynPhase lanterns using a technique where the lantern was functionalized by exposing the lanterns to gamma-radiation from a 60Co radiation source in the presence of carbon tetra-bromide, producing short chain polystyrene tethered bromine atoms, and also with CBr4 directly functionalizing the surface. Styrene was then grafted off these lanterns using ATRP. MMA was graft to the surface of SynPhase lanterns, using g-radiation initiated RATRP at room temperature. It was found that the addition of the thermal initiator, AIBN, successfully increased the concentration of radicals to a level where we could achieve proper control of the polymerization. RAFT was used to successfully control the grafting of styrene, acrylic acid and N,N???-dimethylacrylamide to polypropylene SynPhase Lanterns via a -initiated RAFT agent mediated free radical polymerization process using cumyl phenyldithioacetate and cumyl dithiobenzoate RAFT agents. Amphiphilic brush copolymers were produced with a novel combined RAFT and ATRP system. Polystyrene-co-poly(vinylbenzyl chloride) created using gamma-radiation and controlled with the RAFT agent PEPDA was used as a backbone. The VBC moieties were then used as initiator sites for the ATRP grafting of t-BA to give a P(t-BA) brush that was then hydrolyzed to produce a PAA brush polymer. FMOC loading tests were conducted on all these lanterns to assess their effectiveness as combinatorial chemistry supports. It was found that the loading could be controlled by adjusting the graft ratio of the lanterns and had a comparable loading to those commercially produced by Mimotopes.

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A investigação de sistemas catalíticos duais capazes de mediar as reações de polimerização por abertura de anel via metátese (ROMP) e de polimerização radicalar por transferência de átomo (ATRP) simultaneamente é de grande interesse e importância na obtenção de novos materiais com potencial de aplicação. Neste estudo, novos complexos de Rutênio(II) coordenados a diferentes carbenos N-heterocíclicos derivados de cicloalquilaminas (ciclopentil (IPent) (1a), ciclohexil (IHex) (1b), cicloheptil (IHept) (1c) e ciclooctil (IOct) (1d)) foram sintetizados: [RuCl2(S-dmso)2(IPent)] (2a), [RuCl2(S-dmso)2(IHex)] (2b), [RuCl2(S-dmso)2(IHept)] (2c) e [RuCl2(S-dmso)2(IOct)] (2d). Os sais imidazólicos e seus respectivos complexos de rutênio foram caracterizados por FTIR, UV-Vis, RMN e voltametria cíclica, comprovando-se o sucesso na síntese dos mesmos. Os complexos planejados foram avaliados como precursores catalíticos em reações de ROMP de norborneno (NBE) e em reações de ATRP de metacrilato de metila (MMA). As sínteses de polinorborneno (poliNBE) via ROMP com os complexos 2a-d como pré-catalisadores foram avaliadas sob condições de reação ([EDA]/[Ru] = 28 (5 µL), [NBE]/[Ru] = 5000, temperatura de 50 ºC, utilizando clorofórmio como solvente, variando o tempo até 60 minutos. A polimerização de MMA via ATRP foi conduzida usando os complexos 2a-d na presença de etil-α-bromoisobutirato (EBiB) como iniciador. Os testes catalíticos foram avaliados em função do tempo de reação usando a razão molar [MMA]/[EBiB]/[Ru] = 1000/2/1. Todos os experimentos via ATRP foram conduzidos à 85 °C. A correlação linear do ln([MMA]0/[MMA]) em função do tempo na ATRP de MMA mediada pelos complexos 2a-d indica que a concentração de radicais permanece constante durante a polimerização. As massas moleculares aumentaram com a conversão com a diminuição dos valores de IPD, no entanto, as massas moleculares experimentais foram maiores do que as massas moleculares teóricas. Percebeu-se então que o melhor complexo, para mecanismo via ATRP, na condição descrita, foi o complexo 2d, mostrando uma boa conversão (próximo de 80%) com baixo IPD, enquanto que, para o mecanismo via ROMP, o complexo de melhor atividade foi o 2a.
The investigation of dual catalytic systems able to mediate simultaneously ring-opening metathesis polymerization (ROMP) and atom-transfer radical polymerization (ATRP) reactions is of great interest and importance in obtaining new materials with potential for application. In the study, new complexes of Ruthenium (II) coordinated to different N-heterocyclic carbenes derived from cycloalkylamines (cyclopentyl (IPent) (1a), cyclohexyl (IHex) (1b), cycloheptyl (IHept) (1c) and cyclooctyl (IOct) (1d), [RuCl2(S-dmso)2(IHept)] (2a), [RuCl2(S-dmso)2(IHex)] (2b) [RuCl2(S-dmso)2(IHept)] (2c) and [RuCl2(S-dmso)2(IOct)] (2d). The imidazole salts and their respective ruthenium complexes were characterized by FTIR, UV-Vis, NMR and cyclic voltammetry, proving the success in their synthesis. The planned complexes were evaluated as catalytic precursors in norbornene ROMP (NBE) reactions and in methyl methacrylate (MMA) ATRP reactions. The polynorbornene (polyNBE) syntheses via ROMP with complexes 2a-d as pre-catalysts were evaluated under reaction conditions ([EDA] / [Ru] = 28 (5 μL), [NBE] / [Ru] = 5000, The polymerization of MMA via ATRP was conducted using the complexes 2a-d in the presence of ethyl α-bromoisobutyrate (EBiB) as the initiator.The catalytic tests were evaluated As a function of the reaction time using the molar ratio [MMA] / [EBiB] / [Ru] = 1000/2/1. All ATRP experiments were conducted at 85 °C. The linear correlation of ln ([MMA]0 / [MMA]) as a function of time in MMA ATRP mediated by complexes 2a-d indicates that the concentration of radicals remains constant for a polymerization. As molecular weights increased with a conversion with a decrease in IPD values, however, as experimental molecular masses were higher than as theoretical molecular masses. It was then realized that the best complex, for mechanism via ATRP and in condition, was the 2d complex, showing a good conversion (close to 80%) with low IPD, whereas, for the mechanism via ROMP, the complex of Best activity was the 2a.

Controlled radical polymerizations (CRPs) are among the most powerful methods to obtain polymers with well-defined properties and high commercial value. Atom transfer radical polymerization (ATRP) is probably the most widely used CRP, in academia and industry, thanks to its versatility and simplicity. In ATRP, a metal complex in a low oxidation state, MtzLm (typically a copper-amine system, [CuIL]+) reacts with a dormant polymeric chain Pn–X (where X = Cl, Br) to produce radicals Pn• that can propagate, in the bulk of the solution, by addition to monomer units. In this reaction, the copper complex is oxidized and binds to X–, generating the deactivating species [X-CuIIL]+, which traps the propagating species. ATRP equilibrium is shifted towards the dormant species Pn-X, so that Pn• concentration is very low, and the probability of radical-radical termination events is minimized. Growth of all chains begins virtually at the same time, thanks to the use of alkyl halide (RX) initiators that are more reactive than the dormant species, Pn-X. In such conditions, chain growth is homogenous, and it is possible to obtain polymers with predetermined molecular weight, narrow molecular-weight distribution and high chain-end fidelity. ATRP allows to tailor macromolecules with specific compositions, architectures and position of functional groups. The aim of this thesis is to contribute to both the understanding and development of ATRP catalyzed by copper complexes, using electrochemical methods as equally analytical tools and efficient means of triggering and controlling the polymerization. The work focused on spreading the use of such systems to efficiently control the polymerization of a series of important monomers. Moreover, the investigated ATRP systems can be considered also “green” for several reasons: (i) most of the work regards the study and development of the reaction in green solvents in which copper complexes generally have high catalytic activity; (ii) electrochemical methods for catalyst regeneration (electrochemically mediated ATRP, eATRP) allowed triggering the polymerization with low loadings of copper complexes; (iii) ionic liquids, a class of non-flammable and easily recyclable solvents, were explored as potential media for eATRP; (iv) the mechanism of catalytic halogen exchange was investigated and defined, abridging the synthesis of block copolymers. ATRP catalysts were investigated in the ionic liquid 1-butyl-3-methylimidazolium triflate ([BMIm][OTf]). Both Cu/L speciation and reactivity were found to be suitable for a well-controlled polymerization process. Polymerizations were conducted with electrochemical (re)generation of the active [CuIL]+ complex (eATRP). eATRP of methyl acrylate was investigated in detail by varying a series of parameters such as applied potential, temperature, degree of polymerization and catalyst load ([CuIITPMA]2+, TPMA = tris(2-pyridylmethyl)amine). Application of an electrochemical switch and chain extension with acrylonitrile via catalytic halogen exchange (cHE) proved the livingness of the polymerizations. Experiments triggered in recycled ionic liquid proved that eATRP tolerates well the recycled solvent; polymerizations exhibited good control and high conversion. Block copolymers (BCP) have relevance in a vast range of applications in everyday life. BCP of acrylonitrile (AN) and butyl acrylate (BA) were investigated as precursors for mesoporous carbons. Thus, eATRP of acrylonitrile was studied considering several aspects, including the effect of applied potential, degree of polymerization, C-X nature and initiator structure. A macroinitiator of PAN was then extended with BA to form PAN-b-PBA copolymer as a precursor for mesoporous carbons. BCP can be obtained also by extension of a PBA chain with AN via cHE, thus avoiding purification procedures and reactivity mismatch when crossing from a less reactive monomer to a more reactive one. cHE was proved to be an efficient tool of polymerization by both SARA and eATRP, in a range of solvents, including water. Methyl methacrylate (MMA) was polymerized thanks to cHE in [BMIm][OTf] and ethanol, to solve the issue of penultimate effect. Fine tuning of the electrolysis conditions afforded PMMA with low dispersion. Further improvements were obtained by using [CuIIPMDETA]2+ as an inexpensive and efficient catalyst in alternative to [CuIITPMA]2+. Tacticity analysis of PMMA obtained in [BMIm][OTf] and ethanol confirmed the poor ability of the ionic solvent to induce stereocontrol to the polymerization. Pyridinic complexes such as [CuIITPMA]2+ are stable in very acid conditions (pH = 1). This allowed unprecedented control over conditions of macromolecular growth in water. In addition, it opened a new avenue for the polymerization of ionic liquid monomers (ILMs), a class of building blocks that can give a plethora of new materials. The main reason preventing ATRP of ILM is a cyclization reaction involving the chain-end with the terminal halogen as a leaving group, as in the case of methacrylic acid. Application of three strategies previously developed for ATRP of methacrylic acid allowed to dramatically improve conversion and control over ILMs polymerization. (i) Using C-Cl chain end functionality, which is much more stable than C-Br, (ii) lowering further the pH to completely convert free carboxylate ions to carboxylic acid, which is a much weaker nucleophile, and (iii) enhancing the polymerization rate to avoid the negative contribution of the cyclization side reaction, allowed synthesis of well-controlled high molecular weight poly(ionic liquids), PILs, with degree of polymerization > 500. A simple (poly)halogenated organic initiator such as 2,2-dichloropropionic acid was used to produce linear homotelechelic PILs. Electrochemically mediated ATRP allowed exceptional control over CuI (re)generation. For this reason, it was decided to study the eATRP of vinyl chloride, which was considered impossible until now. The polymerization, triggered in a pressure-resistant electrochemical reactor, was controlled, fast and afforded an acceptable conversion. In addition to linear PVC, a star PVC was also synthesized, highlighting the flexibility of eATRP. In the star architecture, the electrochemical polymerization was by far superior to the chemical one (SARA ATRP). The success of this polymerization has categorically denied the SET-LRP mechanism and its assumptions. One of the crucial properties of electrochemical eATRP is the inert role played by the cathode material used for the regeneration of [CuIL]+. Any electrode material with good stability in the reaction medium can be used as a cathode. It was therefore decided to study the polymerization of an acrylate using the surface of a stainless steel (SS304) reactor exposed to the polymerization mixture as a cathode. In this way, the reactor has the dual function of electrode and place where the reaction takes place. The results showed that polymerization is fast, controlled and reaches high conversions. Moreover, the absence of release of metal ions during the reaction (Fe, Ni, Cr) confirmed that the polymerization takes place via electrochemical reduction of CuII to CuI, while SS304 acts only as an electron reservoir, not chemically involved in ATRP activation. Such simple and cheap electrochemical setup can make the scale-up of the eATRP a reality in the short term and open new economic prospects.
Le polimerizzazioni radicaliche controllate (CRP) sono riconosciute come i metodi più potenti per ottenere polimeri con struttura macromolecolare ben definita e alto valore commerciale. La polimerizzazione radicalica a trasferimento atomico (ATRP) è probabilmente la CRP più utilizzata, in accademia e industria, grazie alla sua versatilità e semplicità. Nell’ATRP, un complesso metallico a basso stato di ossidazione, MtzLm (tipicamente un sistema rame-ammina, [CuIL]+) reagisce con una catena polimerica dormiente Pn-X (dove X = Cl, Br) per produrre radicali Pn•. Questi propagando nel bulk della soluzione, crescono aggiungendo unità monomeriche. In questo processo, il complesso di rame viene ossidato e si lega a X-, generando la specie disattivante [X-CuIIL]+, che intrappola la specie propagante. L'equilibrio di ATRP è fortemente spostato verso la specie dormiente Pn-X, cosicché la concentrazione di radicali sia molto bassa e la probabilità di eventi di terminazione bimolecolare sia ridotta al minimo. La crescita inizia praticamente allo stesso tempo per tutte le catene grazie a iniziatori (alogenuro alchilico) molto efficienti (RX). In tali condizioni, la crescita delle catene è omogenea ed è possibile ottenere polimeri con peso molecolare predeterminato, distribuzione stretta dei pesi molecolari e alta ritenzione della funzionalità di fine catena. L’ATRP consente di costruire dunque macromolecole con specifiche composizioni, architetture e posizionamento dei gruppi funzionali. Lo scopo di questa tesi è di contribuire alla comprensione e allo sviluppo dell’ATRP catalizzata da complessi di rame, utilizzando metodi elettrochimici sia come strumenti analitici che come strumenti per eseguire e controllare la polimerizzazione. Il lavoro si è concentrato sulla diffusione dell'uso di tali sistemi per controllare in modo efficiente la polimerizzazione di una serie di monomeri rilevanti. I sistemi investigati per ATRP possono essere considerati anche "green" per diversi motivi: (i) la maggior parte del lavoro riguarda lo studio e lo sviluppo della reazione in solventi green, generalmente caratterizzati da un'elevata attività catalitica; (ii) i metodi elettrochimici per la rigenerazione del catalizzatore (ATRP mediata elettrochimicamente, eATRP) permette la polimerizzazione con limitata quantità di complessi di rame; (iii) i liquidi ionici, una nuova classe di solventi non infiammabili e facilmente riciclabili, sono stati esplorati come potenziali solventi per eATRP; (iv) il meccanismo di halogen exchange catalitico (cHE) è stato studiato e sviluppato, facilitando la sintesi di copolimeri a blocchi. I catalizzatori ATRP sono stati studiati nel liquido ionico 1-butil-3-metilimidazolio triflato. Sia la speciazione che la reattività di Cu/L sono risultate in linea per un processo di polimerizzazione ben controllato. Le polimerizzazioni sono state condotte con la (ri)generazione elettrochimica del complesso attivo [CuIL]+ (eATRP). L'eATRP del metil acrilato è stata studiata in dettaglio variando una serie di parametri come: potenziale applicato, temperatura, grado di polimerizzazione e carico di catalizzatore di Cu/TPMA (TPMA = tris(2-piridilmetil)ammina). Un interruttore elettrochimico e l'estensione della catena con acrilonitrile (grazie al meccanismo di halogen exchange catalitico) hanno dimostrato la presenza della funzionalità di fine catena. Le polimerizzazioni ottenute tramite liquido ionico riciclato hanno dimostrato che eATRP tollera bene anche un solvente riciclato. I copolimeri a blocchi (BCP) hanno rilevanza in una vasta gamma di applicazioni nella vita di tutti i giorni. BCP di acrilonitrile (AN) e butil acrilato (BA) sono stati studiati come precursori di carbonio mesoporoso. Pertanto, eATRP di acrilonitrile è stata introdotta e studiata nei diversi aspetti, come: effetto del potenziale applicato, del grado di polimerizzazione, della natura di C-X e della struttura dell'iniziatore. Un macroiniziatore di PAN è stato quindi esteso con BA per formare il copolimero PAN-b-PBA come precursore del carbonio mesoporoso. I BCP possono essere ottenuti anche via cHE, evitando così le procedure di purificazione e la differenza di reattività quando si passa da un monomero meno reattivo a uno più reattivo. Il cHE si è dimostrato strumento efficace di polimerizzazione sia da SARA che da eATRP, in una gamma di solventi incluso DMSO e acqua. Il metil metacrilato (MMA) è stato polimerizzato grazie al cHE in liquido ionico ed etanolo, per risolvere il problema dell’effetto del penultimo. La messa a punto delle condizioni di elettrolisi ha permesso di ottenere PMMA a bassa dispersione. Ulteriori miglioramenti sono stati ottenuti utilizzando [CuIIPMDETA]2+ come catalizzatore come alternativa economica ed efficiente a Cu/TPMA. L'analisi della tatticità del PMMA ottenuta in [BMIm][OTf] e l'etanolo ha confermato la scarsa capacità del solvente ionico di indurre stereocontrollo durante la polimerizzazione. I complessi piridinici, come Cu/TPMA, stabili fino a condizioni molto acide (pH ⁓1) hanno permesso di ottenere poli(liquidi ionici). Hanno aperto infatti una nuova strada per la polimerizzazione di monomeri liquidi ionici, una classe di molecole che può dare una pletora di nuovi materiali polimerizzati mediante ATRP. La ragione principale che impedisce l'ATRP di ILM è una reazione di ciclizzazione che coinvolge l'estremità della catena, con l'alogeno terminale come gruppo uscente, come nel caso dell'acido metacrilico. Le stesse tre strategie usate per l’acido metacrilico hanno permesso di migliorare drasticamente la conversione e il controllo sulla polimerizzazione di ILM: (i) usando la funzionalità di fine catena C-Cl, che è molto più stabile di C-Br; (ii) abbassando il pH per convertire completamente gli ioni carbossilato liberi in acido carbossilico, che è un nucleofilo molto più debole; (iii) migliorare la velocità di polimerizzazione per evitare il contributo negativo della reazione di ciclizzazione. Tali condizioni hanno permesso la sintesi di poli(liquidi ionici) (PIL) ben controllati ad alto peso molecolare fino a grado di polimerizzazione 1000. Un semplice iniziatore organico (poli)alogenato come acido 2,2-dicloropropionico è stato utilizzato per produrre un PIL lineare telechelico. L’insieme di questi risultati può consentire una più facile implementazione e scalabilità industriale dell’eATRP. Per questo motivo, è stato deciso di studiare l’eATRP del cloruro di vinile, considerata finora impossibile. La polimerizzazione, effettuata in un reattore elettrochimico resistente alla pressione, è controllata, veloce e con una conversione buona in tempi ragionevoli. Oltre al classico PVC lineare, è stato anche sintetizzato un PVC a stella, evidenziando la flessibilità dell'eATRP. Nell'architettura a stella, la polimerizzazione elettrochimica si è dimostrata di gran lunga superiore a quella chimica (SARA ATRP). Il successo di questa polimerizzazione ha smentito il meccanismo SET-LRP e le sue assunzioni. Una delle proprietà dell’eATRP è la tolleranza al materiale catodico utilizzato per la rigenerazione di [CuIL]+. Si è deciso dunque di studiare la polimerizzazione di un acrilato usando la superficie del reattore esposto alla miscela di polimerizzazione come elettrodo. In questo modo il reattore ha la duplice funzione di elettrodo e luogo fisico in cui avviene la reazione. I risultati hanno mostrato che la polimerizzazione è veloce e controllata, raggiungendo conversioni elevate in breve tempo. Inoltre, l'assenza di rilascio di ioni metallici durante la reazione (Fe, Ni, Cr) da parte dell’acciaio conferma che la polimerizzazione avviene elettrochimicamente, l'acciaio agisce solo come un serbatoio di elettroni e non è chimicamente coinvolto. Una tale impostazione elettrochimica, semplice ed economica, può rendere l'eATRP una tecnica commerciale a breve termine e aprire nuove prospettive economiche.