This thesis presents a study of the preparation and characterisation of microgels (MGs) and microgel-based systems which contain a high proportion of primaryamine groups. This is carried out with the aim of being used as the precursor materials for the development of an enzyme responsive system. The particle preparations discussed in this thesis begin with a particle dispersion prepared by a polymer-polymer interaction between partially oxidised dextran (Dexox) and poly(allylamine)(PA) or poly(vinylamine) (PVAM). The particle dispersions did show good tunability of properties by altering certain variables, such as extent of oxidation which resulted in the largest  -potential change with pH. However, these particles were not viable for further work as the largest swelling ratio by volume, Q value measured was only around 1.25, not sufficient for a pH responsive property swelling change (e.g. fluid-to-gel transition or drug delivery). MG particles were prepared using a non-aqueous dispersion polymerisation of Nvinylformamide (NVF), glycidylmethacrylate (GMA) and a crosslinker, 2-(Nvinylformamido)ethyl ether (NVEE). The PNVFx-GMAy-NVEEz particles were then hydrolysed to expose the primary amine groups in the resulting PVAMx-GMAy-BEVAMEz core-shell MGs. The shell, made up of GMA and NVF prevented hydrolysis taking place on the inside of the MGs, resulting in a PVAM rich shell. These hydrolysed MGs were cationic at low pH and were shown to have polyampholyte behaviour, caused by hydrolysis of some of the GMA groups. The inclusion of the NVEE crosslinker led to increased integration of the GMA and NVF into one homogenous phase in the shell and prevented hydrolytic fragmentation. The final system studied here concerns the macroscopic gel formation between the amine-rich MGs, poly(vinylamine-co-bis(ethyl vinylamine)ether) (PVAMBEVAME)and Dexox. These mixed dispersion gels were prepared and characterised. The MGs were externally crosslinked with the Dexox in order to form an elastically effective network. This was done by forming imine bonds by reaction between the primary amine groups present on the MGs and the aldehyde groups of the Dexox. These networks displayed high storage modulus (G’) and yield strains(*) of up to 140% and the G’ values for the MG-Dexox gels increased with mass ratio (MR) of Dexox to MG. The yield strains determined from rheology remained high (~125%) with increased MR. As the imine bonds formed were not reduced, they became unstable at low pH. This was exploited in order to investigate pH-triggered gel disruption of the network. This work demonstrates that new MG/aldehyde mixtures form ductile and versatile colloidal gels and our new method provides a route to increasing ductility of hydrogels containing MG particles. This research has led to the formation of amine rich MGs, as well as an injectable gel system. These materials are well placed to be developed for enzyme responsive materials in the future.

Amine transaminases are enzymes that catalyze the mild and selective formation of primary amines, which are useful building blocks for biologically active compounds and natural products. In order to make the production of these kinds of compounds more efficient from both a practical and an environmental point of view, amine transaminases were incorporated into multi-step one-pot reactions. With this kind of methodology there is no need for isolation of intermediates, and thus unnecessary work-up steps can be omitted and formation of waste is prevented. Amine transaminases were successfully combined with other enzymes for multi-step synthesis of valuable products: With ketoreductases all four diastereomers of a 1,3-amino alcohol could be obtained, and the use of a lipase allowed for the synthesis of natural products in the form of capsaicinoids. Amine transaminases were also successfully combined with metal catalysts based on palladium or copper. This methodology allowed for the amination of alcohols and the synthesis of chiral amines such as the pharmaceutical compound Rivastigmine. These examples show that the use of amine transaminases in multi-step one-pot reactions is possible, and hopefully this concept can be further developed and applied to make industrial processes more sustainable and efficient in the future. / <p>QC 20170113</p>

<p>N-chloramide containing and primary amine-containing microgels were prepared by post-modification of thermosensitive microgels in alkaline bleach. The objective of this project was to develop simple strategies for preparation of functionalized microgels.</p> <p>N-chlorination of linear poly(N-isopropylacrylamide) (PNIPAM) in bleach at high pH resulted in a novel N-chloramide containing copolymer: poly(NIPAM-co-NIPAMCl). The chlorinated PNIPAM showed controlled phase transition temperature and oxidative ability. The N-chlorination of linear PNIPAM inspired the preparation of N-chloramide containing PNIPAM microgels in a similar way. The phase transition temperature of the resulted chlorinated microgels, which corresponds to the extent of N-chlorination, was affected by the reaction temperature and salt concentration. The reaction between the chlorinated microgels and glutathione is proposed as diffusion controlled.</p> <p>The N-chlorination of poly(N-isopropylmethacrylamide) (PNIPMAM) microgels in bleach was restricted, in comparison with PNIPAM microgels. The active chlorine content of chlorinated PNIPMAM microgels was about one-tenth of that of chlorinated PNIPAM microgels under the same N-chlorination condition. It is proposed that the high stability of PNIPMAM in bleach is a result of the electron-donating effect of methyl groups on PNIPMAM backbone. Hence, core-shell microgels with PNIPAM cores and poly(NIPAM-co-NIPMAM) shells showed improved colloidal stability after N-chlorination because the shell was less chlorinated and served as a steric stabilizer.</p> <p>Finally, primary amine-containing microgels were prepared via Hofmann rearrangement of copolymers of methacrylamide, which decomposed to give amines, and NIPMAM, which did not react. The method was further extended to give amphoteric microgels by including acrylic acid in the starting microgels. Although other approaches to aminated and amphoteric microgels have been developed, this approach is particularly attractive because of the ease of the reaction and the ability to control the microgel isoelectric points.</p> / Doctor of Philosophy (PhD)

No description available.

Récemment, les exigences en chimie ont évolué rapidement, car le développement durable a retenu plus d'attention. Les principes de la chimie verte ont encouragé les chimistes à développer des produits chimiques et des procédés qui réduisent ou éliminent les substances dangereuses. Les travaux de recherche décrits dans cette thèse portent sur le développement de nouveaux systèmes réducteurs en utilisant des hypophosphites comme substituts aux agents réducteurs toxiques traditionnels.Pour atteindre cet objectif, les nitriles aromatiques ont été réduits en aldéhydes correspondants par la formation du gaz de l’hydrogène et de nanoparticules de nickel en combinant un précurseur de nickel avec de l'hypophosphite de calcium en présence d'une base dans un milieu biphasique. De plus, les nitriles aromatiques ont été réduits en amines primaires en utilisant de l'hypophosphite de calcium et le catalyseur hétérogène palladium sur le carbone. La nature du catalyseur métallique, les additifs, les solvants, la température et les concentrations ont été étudiés en détail.D'autre part, l'amination réductrice directe des cétones aliphatiques et aromatiques a été réalisée pour la première fois en utilisant du palladium hétérogène sur du carbone et de l'hypophosphite d'ammonium qui agit comme une source d'ammoniac et un agent réducteur en même temps. Au cours de l'optimisation, des différents paramètres ont été étudiés / Recently, requirements in chemistry are changing fast, since sustainable development has retained more attention. Green chemistry principles have promoted chemists to develop chemical products and processes that reduce or eliminate hazardous substances. The research work described in this thesis is focused on the development of new reducing systems using hypophosphites as substitutes for traditional toxic reducing agents.In order to achieve this goal, aromatic nitriles were reduced into the corresponding aldehydes by the formation of hydrogen gas and nickel nanoparticles upon combining a nickel precursor with calcium hypophosphite in the presence of base in a biphasic medium. Moreover, aromatic nitriles were reduced into primary amines using calcium hypophosphite and the heterogeneous catalyst palladium on carbon. The nature of the metal catalyst, additives, solvents, temperature, and concentrations were studied in details.On the other hand, the well-known direct reductive amination of aliphatic and aromatic ketones was done for the first time using heterogeneous palladium on carbon, and ammonium hypophosphite which acts as a source of ammonia and as a reducing agent at the same time. During optimization different parameters were studied