Thermo-responsive homopolymer poly(N-isopropylacrylamide), is a widely studied and used polymer. Our recent observations on thermal behavior of aqueous solutions of this polymer requires a short overview of existing results in order to understand the formation of different phases, both stable and unstable with the addition of hydrophilic Ionic liquids (ILs) 1-Butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]), 1-Butyl-3-methylimidazolium acetate ([BMIM][OAc]) and 1-Butyl-3-methylimidazolium thiocyanate ([BMIM][SCN]) to the system. PNIPAM is soluble in cold water due to its inter- and intramolecular hydrogen bonding but phase separates upon heating at T > 32 , which is its lower critical solution temperature (LCST). PNIPAM exists in an expanded coil like conformation in water below its LCST which gives a transparent homogenous solution but at T > LCST it undergoes hydrophobic collapse marked by cloudiness of solution and conformational change from coil to globule state. All aqueous PNIPAM solutions undergo phase separation or cloud point transition at T > 32 , regardless of the molar mass of the polymer. Room temperature Ionic liquids (ILs) are unique designer fluids because of the novel physico-chemical properties arising from their structure, which have tremendous implications in the field of IL as solvents or co-solvents for polymeric solutes. During recent years a number of different imidazolium based ILs have also been tested for solubilization and stabilization of proteins as well as polymers due to hydrogen bond formation of the IL ions. Recent studies have shown that certain imidazolium based ILs can decrease the LCST of PNIPAM aqueous solution by hydrophobic collapse/aggregation of the PNIPAM chains, as well as some can induce an upper critical solution temperature (UCST) behavior of PNIPAM in neat IL solution. Even so, experimental studies of such phase transition/ instability of thermoresponsive polymer-IL systems has been a challenging task. In this research we have explored the critical solution temperature (CST) type phase behavior of multicomponent systems i.e. PNIPAM in solution media of water, neat IL and aqueous solutions of IL. The overall fundamental challenge is to understand how the interactions among the components control both structure and dynamics of PNIPAM network in solution. For example the disruption of hydrogen bonding or desolvation interactions between blocks of a PNIPAM molecule and solvent molecules in aqueous mixtures that lead to a LCST type transition at higher temperatures. Interestingly, it was found in our case that PNIPAM shows both LCST and UCST-type phase transition in some aqueous solutions of hydrophilic IL [BMIM][BF4]. It was found for the first time that this IL can influence the LCST type behavior of PNIPAM in aqueous solutions based on our visual and experimental cloud point (CP) observations. In our experiments the effect of the ILs [BMIM][BF4] and [BMIM][OAc] is qualitatively similar to influence of Kosmotropic salts on the LCST of aqueous PNIPAM solutions as predicted by the Hofmeister series.

Polymer magnetic composite (PMC) nanoparticles have gained a large attention due to their potential use in several biomedical applications from biomedical to engineering field. Among the different heterogeneous polymerization techniques that are generally used to prepare hybrid polymer particles, miniemulsion polymerization is proved to be an efficient one. The occurrence of preferential droplet nucleation in case of miniemulsion polymerization results in a 1:1 copy of monomer droplets to the polymer particles and such a mechanistic pathway offers a suitable environment for the preparation of hybrid polymer nanoparticles in the range between 50 to 500 nm. The surfactant in miniemulsoin plays a significant role to stabilize the droplets/particles and also in the encapsulation of nanoparticles. In the present study, a new class of surfactant, called amphiphilic ionic liquid, has been employed in the field of miniemulsion. The amphiphilic ionic liquid has amazing ability to impart surface tunable characteristics to the polymer particles when present on the surface of the particles. Thus the aim of the present work is to synthesize polymer magnetic composite nanoparticles with good colloidal stability, high content of magnetic nanoparticles as well as the chance for further surface functionality. Such magnetic nanoparticles may find applications in various fields. At first, the aim of the work was to establish a suitable recipe with ionic liquid as surfactant for the execution of miniemulsion polymerization. Monodisperse polystyrene nanoparticles were possible to be synthesized reproducibly. The established recipe was utilized to carry out the synthesis of PMC nanoparticles. Iron oxide (Fe3O4) was taken as magnetic nanoparticles (MNP) and it was hydrophobized with oleic acid to disperse in styrene. The concentration of feed MNP was varied to observe its influence on the characteristics of PMC nanoparticles. Stable dispersion of magnetic polystyrene particles was possible to be synthesized up to 8 wt% feed MNP. But feeding 12 wt% MNP resulted in the development of large amount of coagulum associated with instability in the dispersion. TGA investigation confirmed a significantly lower MNP content (8.2 wt%) of the composite compared to the feed amount. TEM investigation showed inhomogeneous distribution of MNP among polystyrene particles and agglomeration of MNP was observed on the surface of polystyrene particles. Considering the inability of the single step miniemulsion polymerization for the preparation of high MNP content polymer particles, it was aimed to find a new strategy which can produce such material. Inspired from the affinity of carboxylic acid group towards the surface of MNP, it was aimed to synthesize carboxyl functionalized polystyrene which was expected to improve the interaction between polymer and magnetic nanoparticles. For this purpose, RAFT mediated miniemulsion polymerization was performed in presence of a carboxyl functionalized chain transfer agent (CTA). The colloidal stability was much better compared to the previous case of non-RAFT experiments. From a feed MNP of 8 wt%, a high final MNP content up to ~27 wt% could be achieved and all the dispersions were highly stable. The higher MNP content in the final composites compared to the feed ratio was a result of the low monomer conversion and could be adjusted by a proper tuning of AIBN to CTA mole ratio. Another significant influence of the carboxyl functionalized CTA was observed on the morphology of the composite nanoparticles. The MNP were distributed homogeneously among the PS particles. Regarding the dispersion of MNP in the individual polystyrene particles, it was observed that higher amount of CTA resulted in a homogeneous dispersion of MNP whereas higher amount of initiator ended up producing asymmetric Janus like morphology. Apart from that, due to the involvement of CTA in the polymerization, much lower molecular weight of the polystyrene chains was developed compared to the free radical process and the molecular weight distribution of PS in the composite nanoparticles became much narrower through the RAFT polymerization. Thus a relatively good control over the polymerization process was achieved through RAFT polymerization which was confirmed by a nearly linear increase of molecular weight (Mn) with time of polymerization and thus, monomer conversion. In the recipe of miniemulsion, costabilizer plays an important role to retard monomer diffusion from smaller to larger droplets. Hexadecane, being the most frequently used costabilizer for miniemulsion, has been employed in this study so far. But its volatile nature restricts its utilization in several applications. For the replacement of hexadecane, a carboxyl functionalized polystyrene is employed as a costabilizer as well as a macro CTA in miniemulsoin polymerization of styrene. For this purpose, low molecular weight carboxyl bi-functionalized polystyrene (9000 g/mole) was synthesized by thermal bulk RAFT polymerization. The carboxylated polystyrene worked successfully as a costabilizer in miniemulsion and molecular weight investigation confirmed the integration of the carboxyl functionalized macro CTA into the developing polystyrene chain via RAFT polymerization. This strategy was employed successfully to synthesize stable dispersion of PMC nanoparticles with a reasonable content of MNP in the system. A homogeneous morphology was observed regarding the distribution of MNP among the polystyrene particles. The strategy of using macro CTA as costabilizer can be utilized to synthesize various functional copolymers with control architecture without any added monomer and CTA in the system. Moreover, presence of functionality within the monomer droplets can be effective to encapsulate several nanomaterials using miniemulsion polymerization.

Today’s consumption of textiles generates a large volume of textile waste. Therefore, it is needed to find solutions to re-use the textile waste rather recycling fibers into new fibers. Research using pre- and post-consumer textiles in composites is ongoing and an interesting direction. This thesis reports the recycling of discharged cellulose containing textiles by production of all-cellulose composites (ACCs). ACCs are composites consisting entirely of cellulose. ACCs from discarded denim and polycotton hospital sheets (PCO) were successfully produced with partial dissolution and two-step method. Discarded denim fabrics with 100% cotton (CO) and blend material (BCO) was sorted and shredded into fibers, then made into nonwovens by needle punching. The produced nonwoven laminates and intact hospital sheets were used as the reinforcement in the composites while dissolved cellulose in an ionic liquid (IL), 1-butyl-3-methyl imidazolium acetate ([BMIM][Ac]), was used as the matrix phase. The matrix is then regenerated by removal of the [BMIM][Ac] by washing to form the composite. The washed-out [BMIM][Ac] was collected and recycled in order to study the effect of its reusing as recycled cellulose solvent on mechanical properties of ACCs. Combinations of the different methods, materials and solvents were studied. The mechanical properties – tensile, flexural and impact properties and the void content of the produced composites were deter-mined. Microscopic analysis was done to study the cross-section of the composites. It could be concluded that the achieved values for the mechanical properties can be compared with ACCs found in literature. The results from the research implies that it is possible to find a new purpose for recycled textiles in the form of composites. With this approach, it is possible to avoid unnecessary disposal of textiles containing cellulose.

La cristallisation par effet anti-solvant, comme technique de production de micro/nanoparticules, présente certains inconvénients. En effet, pour des molécules nouvellement synthétisées ou découvertes, comme le LASSBio-294, les solubilités dans l'eau et dans les solvants organiques sont faibles ce qui limite l'application de cette opération. L'utilisation de solvants alternatifs ouvre de nouvelles perspectives de recristallisation de ce type de molécules. Dans ce travail, nous nous sommes intéressés à la cristallisation du LASSBio-294 en utilisant un liquide ionique comme solvant. Ce sont des sels organiques fondus à température ambiante, qui ont la particularité d’avoir une tension de vapeur nulle. Ils constituent une nouvelle classe de solvants non volatiles et ininflammables qui présentent des propriétés originales. Dans un premier temps, des liquides ioniques (LIs) dérivés du cation imidazolium ont été utilisés comme solvant alternatif. La solubilité a été mesurée dans 5 LIs,dans l’eau et dans des mélanges eau/LI. Dans l’eau pure la solubilité est très faible (5 ppm). En revanche, dans certains LIs, elle est supérieure à 200 mg/g solution. Les résultats de solubilité dans des mélanges eau/LI ont permis de choisir le rapport eau/LI pour l’obtention d’un bon rendement en solide. En complément, une étude de la stabilité du solide en suspension a été menée dans différents systèmes aqueux. Cette étude a montré sa possible hydrolyse. Dans un deuxième temps, la recristallisation a été réalisée avec le 1-éthyl-3-méthylimidazolium méthyl phosphonate [emim][CH3O(H)PO2] comme solvant et l’eau comme anti-solvant. Deux approches sont présentées en vue de favoriser le mélange : l'utilisation de dispositifs de mélange et l'introduction des ultrasons pendant le processus de cristallisation. L’influence de paramètres tels que le rapport anti-solvant/solvant, la concentration initiale et la présence d'additifs a été étudiée. Les solides formés puis séchés en étuve ont été caractérisés par granulométrie laser, microscopie électronique à balayage, diffractométrie de rayons X, calorimétrie différentielle à balayage et test de dissolution. Malgré une diminution de la taille des particules élémentaires, l'état d'agglomération des cristaux obtenus n'a pas permis une augmentation de la vitesse de dissolution. En modifiant le mode de séchage (séchage par atomisation), cette agglomération est réduite et la dissolution améliorée. De plus, la présence d'un polymère entérique en solution lors du séchage par atomisation des cristaux synthétisés a eu un effet notable sur la structure des agglomérats formés. Ces derniers peuvent se désagréger, se disperser et se dissoudre rapidement. / The anti-solvent crystallization allows obtaining micro/nanoparticles, but it presents some disadvantages. In the case of new pharmaceutical molecules, as the LASSBio-294, the solubility in water or organic solvents is very low limiting the application of this operation. The use of Ionic Liquids (ILs) as alternative solvents opens new perspectives in pharmaceutical processing through anti-solvent crystallization process. Unlike conventional solvents, ILs are entirely composed of ions. ILs are organic salts, usually liquid at room temperature, and which are composed of a relatively large asymmetric organic cation and of an inorganic or organic anion. ILs derived from imidazolium cation are used as alternative solvents for this drug, water being used as anti-solvent. First, the solubility is measured in 5 ILs, in water and in water/IL mixtures. In pure water, the solubility is very low (5 ppm). However, for some ILs, it is greater than 200 mg/g solution. The results of solubility in water/IL mixtures permit to choose a water/IL ratio leading to a good solid theoretical yield. Then recrystallization is performed with 1-ethyl-3-methylimidazolium methyl phosphonate [emim][CH3O(H)PO2] as the preferred solvent. Antisolvent crystallization represents a class of process characterized by the mixing between a solution and an antisolvent to produce solid particles. The influence of solvent/anti-solvent ratio, initial concentration, and additives is studied. The solids formed and dried in an oven are characterized by laser granulometry, scanning electron microscopy, X-ray diffraction, differential scanning calorimetry, and dissolution test. Despite the decrease of elementary particles size, the agglomeration state of particles does not permit to improve the dissolution rate. The agglomeration is reduced and the dissolution improved by modifying the drying process (spray drying). Moreover, the presence of an enteric polymer during the spray drying process has a significant impact on the structure of the formed agglomerates. These are disaggregated, dispersed and dissolved very quickly.

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京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21124号 / 工博第4488号 / 新制||工||1697(附属図書館) / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 辻井 敬亘, 教授 山子 茂, 教授 竹中 幹人 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Superkondensatorer är energilagringsenheter som har uppmärksammats mer under det senaste decenniet. Några av de fördelar som dessa enheter har varit är lagring av hög effekttäthet, förlängda livscykler och snabba laddnings- och urladdningstider. Dock är superkondensatorer fortfarande begränsade i energitäthet i jämförelse med batterier. För att få högre effekt och energitäthet är en asymmetrisk hybrid superkondensator ett bra alternativ. Denna enhet består av en kolbaserad elektrod för icke-faradaiska reaktioner och en kolelektrod kombinerad med metalloxider för redoxreaktioner. Materialvalet spelar en avgörande roll för förmågan en hybrid asymmetrisk superkondensator ska ha. I denna studie undersöks fyra olika kommersiella kol. Den specifika ytan, porstorlekarna och morfologin jämförs. Dessutom syntetiseras metalloxidernanopartiklar MnO2 och kristallstrukturen undersöks. Därtill beläggs MnO2-partiklarna på de fyra kolen och tillväxten av dessa undersöks. Slutligen analyseras interaktionen mellan jonvätskan 1-butyl-3-metylimidazoliumtetrafluorborat (BMIM[BF4]) som en elektrolyt och de olika kolen. / Supercapacitors are energy storage devices that have drawn attention for the past decade. Some of the advantages of these devices are higher power density storage, extended life cycles, and fast charge and discharge times. However, supercapacitors are still limited in energy density compared to batteries. To obtain higher power and energy densities, a hybrid asymmetric supercapacitor is a good alternative. This device consists of one carbon-based electrode for non-faradaic reactions, and one carbon electrode combined with metal oxides for redox reactions. The material choice is important for the capability of a hybrid asymmetric supercapacitor. In this study, four different commercial carbons are investigated. The specific surface area, pore sizes, and morphology are compared. In addition, metal oxide nanoparticles MnO2 are synthesised, and crystal structure is investigated. Furthermore, the MnO2 particles are deposited on the four carbons and the growth of those is studied. Finally, the interaction between ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM[BF4]) as an electrolyte and the different carbons is studied.

Lignin is one of the most abundant natural polymers on Earth, and a valuable resource. Despite being widely available, only a small amount of the produced lignin is currently utilized to make high-value goods, with the majority being used for pulp mills to recover energy. However, the possibility to convert lignin into commercially viable products is presented by the rising need for sustainable and renewable resources. In the past, research has mostly concentrated on converting lignin into chemicals, materials, and biofuels; nevertheless, there has not been much advancement in practical applications. Lignin is difficult to depolymerize due to its intricate structure and resistance to degradation. To separate lignin from lignocellulosic biomass, a number of techniques have been developed, such as kraft and sulfite pulping. These techniques, though, result in lignin with various characteristics. As a result, improved lignin isolation methods are required in order to produce high-quality, pure lignin. Due to its capacity to solubilize lignocellulosic biomass and extract lignin, ionic liquid-based lignin isolation has attracted interest. Ionic liquids are environmentally friendly since they may be recycled and used again. There are still issues with toxicity, physicochemical data, and industrial-scale recovery, though. Lixea is a startup company that specializes in sustainable technology, especially lignin. They have created a novel method of fractionating lignocellulose known as Dendronic® that uses inexpensive ionic liquids to separate lignin and cellulose from biomass. Potentially, this process could result in renewable products, such as chemicals and biofuels on a large scale. Filtration of the lignin is one of the main bottlenecks operations at Lixea`s pilot plan. In this paper two different strategies; Maturing of the lignin suspension through temperature cycling and using previously isolated lignin filter cake as precipitation and filtration aid, have been tested out at the lab scale to improve the lignin filtration speed. Based on the observations in this work the heat treatment strategy is the most promising one, therefore it is recommended to test it the pilot plant to confirm the lab-scale experiments and improve the plant operation. Overall, further research and development are needed to unlock the full potential of lignin as a flexible and sustainable resource.

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No description available.