<p>This thesis describes the synthesis and characterization ofbranched semi-crystalline polymers. Included in this work isthe SEC characterization of a series of dendrimers. Thebranched semi-crystalline polymers were synthesized in order toinvestigate the concept of their use as powder coatings resins.This concept being that the use of branched semi-crystallinepolymers in a UV-cured powder coating system may offer a lowertemperature alternative thus allowing the use of heat sensitivesubstrates and the added benefit of a reduced viscositycompared to linear polymers.</p><p>A series of branched poly(ε-caprolactone)’s (PCL)(degree of polymerization: 5-200) initiated from hydroxylfunctional initiators were synthesized. The final architectureswere controlled by the choice of initiator structure;specifically the dendritic initiators yielded starbranchedPCL’s while the linear initiator yielded comb-branchedPCL’s. The dendritic initiators utilized were: (1) a3rd-generation Boltorn H-30, commercially availablehyperbranched polyester with approximately 32 hydroxyl groups,(2) a 3rd-generation dendrimer with 24 hydroxyl groups, and (3)a 3rd-generation dendron with 8 hydroxyl groups. Linear PCL wassynthesized for comparison. All dendritic initiators are basedon 2,2- bis(methylol) propionic acid. The comb-branchedpolymers were initiated from a modified peroxide functionalpolyacrylate. The resins were end-capped withmethylmethacrylate in order to produce a cross-linkable system.The polymers and films were characterized using 1H NMR, 13CNMR, SEC, DMTA, DSC, FT-IR, FT-Raman, rheometry and a rheometercoupled to a UV-lamp to measure cure behavior.</p><p>The star-branched PCL’s exhibited considerably lowerviscosities than their linear counterparts with the samemolecular weight for the molecular region investigated (2-550kg mol-1). It was also found that the zero shear viscosityincreased roughly exponentially with M.</p><p>The PCL star-branched resins are semi-crystalline and theirmelting points (Tm) range from 34-50°C; films can beformed and cured below 80°C. The viscoelastic behaviourduring the cure showed that the time to reach the gel point, afew seconds, increased linearly with molecular weight. Thecrossover of G’and G’’was used as the gelpoint. Measurement of mechanical properties of films showedthat the low molecular weight polymers were amorphous whilethose with high molecular weight were crystalline after cure.The polymerization of 5,5-dimethyl-1,3-dioxane-2-one (NPC) fromoligo- and multifunctional initiators was evaluated utilizingcoordination and cationic polymerization. Two tin basedcatalysts, stannous(II) 2-ethylhexanoate and stannous(II)trifluoromethane sulfonate, were compared with fumaric acid.Fumaric acid under bulk conditions resulted in lowerpolydispersity and less chance of gelling. The synthesis ofstar-branched polymers was confirmed by SEC data. The starpolymers exhibited a Tg at 20-30°C and a Tm at about100°C.</p><p>All semi-crystalline resins exhibited a fast decrease inviscosity at Tm. Blends of combbranched semi-crystalline resinsand amorphous resins exhibited a transition behavior inbetweenthat of pure semi-crystalline resins and that of amorphousresins.</p><p>The SEC characterization of a series of dendrimers withdifferent cores and terminal groups showed that the core had animpact on the viscosimetric radius of the core while theterminal groups appeared to have no effect.</p><p><b>Keywords:</b>star-branched, semi-crystalline,comb-branched, ring-opening polymerization,poly(ε-caprolactone), dendritic, thermoset, lowtemperature curing, powder coating, UVcuring,poly(5,5-dimethyl-1,3-dioxane-2-one), size exclusionchromatography, rheology, dendritic aliphatic polyester</p>

No description available.

This thesis describes the synthesis and characterization ofbranched semi-crystalline polymers. Included in this work isthe SEC characterization of a series of dendrimers. Thebranched semi-crystalline polymers were synthesized in order toinvestigate the concept of their use as powder coatings resins.This concept being that the use of branched semi-crystallinepolymers in a UV-cured powder coating system may offer a lowertemperature alternative thus allowing the use of heat sensitivesubstrates and the added benefit of a reduced viscositycompared to linear polymers. A series of branched poly(ε-caprolactone)’s (PCL)(degree of polymerization: 5-200) initiated from hydroxylfunctional initiators were synthesized. The final architectureswere controlled by the choice of initiator structure;specifically the dendritic initiators yielded starbranchedPCL’s while the linear initiator yielded comb-branchedPCL’s. The dendritic initiators utilized were: (1) a3rd-generation Boltorn H-30, commercially availablehyperbranched polyester with approximately 32 hydroxyl groups,(2) a 3rd-generation dendrimer with 24 hydroxyl groups, and (3)a 3rd-generation dendron with 8 hydroxyl groups. Linear PCL wassynthesized for comparison. All dendritic initiators are basedon 2,2- bis(methylol) propionic acid. The comb-branchedpolymers were initiated from a modified peroxide functionalpolyacrylate. The resins were end-capped withmethylmethacrylate in order to produce a cross-linkable system.The polymers and films were characterized using 1H NMR, 13CNMR, SEC, DMTA, DSC, FT-IR, FT-Raman, rheometry and a rheometercoupled to a UV-lamp to measure cure behavior. The star-branched PCL’s exhibited considerably lowerviscosities than their linear counterparts with the samemolecular weight for the molecular region investigated (2-550kg mol-1). It was also found that the zero shear viscosityincreased roughly exponentially with M. The PCL star-branched resins are semi-crystalline and theirmelting points (Tm) range from 34-50°C; films can beformed and cured below 80°C. The viscoelastic behaviourduring the cure showed that the time to reach the gel point, afew seconds, increased linearly with molecular weight. Thecrossover of G’and G’’was used as the gelpoint. Measurement of mechanical properties of films showedthat the low molecular weight polymers were amorphous whilethose with high molecular weight were crystalline after cure.The polymerization of 5,5-dimethyl-1,3-dioxane-2-one (NPC) fromoligo- and multifunctional initiators was evaluated utilizingcoordination and cationic polymerization. Two tin basedcatalysts, stannous(II) 2-ethylhexanoate and stannous(II)trifluoromethane sulfonate, were compared with fumaric acid.Fumaric acid under bulk conditions resulted in lowerpolydispersity and less chance of gelling. The synthesis ofstar-branched polymers was confirmed by SEC data. The starpolymers exhibited a Tg at 20-30°C and a Tm at about100°C. All semi-crystalline resins exhibited a fast decrease inviscosity at Tm. Blends of combbranched semi-crystalline resinsand amorphous resins exhibited a transition behavior inbetweenthat of pure semi-crystalline resins and that of amorphousresins. The SEC characterization of a series of dendrimers withdifferent cores and terminal groups showed that the core had animpact on the viscosimetric radius of the core while theterminal groups appeared to have no effect. Keywords:star-branched, semi-crystalline,comb-branched, ring-opening polymerization,poly(ε-caprolactone), dendritic, thermoset, lowtemperature curing, powder coating, UVcuring,poly(5,5-dimethyl-1,3-dioxane-2-one), size exclusionchromatography, rheology, dendritic aliphatic polyester / <p>NR 20140805</p>

Casein is the major protein fraction in milk, and its cross-linking has been a topic of scientific interest for many years. Enzymatic cross-linking has huge potential to modify relevant techno-functional properties of casein, whereas non-enzymatic cross-linking occurs naturally during the storage and processing of milk and dairy products. Two size separation techniques were applied for characterisation of these reactions: gel electrophoresis and size exclusion chromatography. This review summarises their separation principles and discusses the outcome of studies on cross-linked casein from the last ~20 years. Both methods, however, show limitations concerning separation range and are applied mainly under denaturing and reducing conditions. In contrast, field flow fractionation has a broad separation range and can be easily applied under native conditions. Although this method has become a powerful tool in polymer and nanoparticle analysis and was used in few studies on casein micelles, it has not yet been applied to investigate cross-linked casein. Finally, the principles and requirements for absolute molar mass determination are reviewed, which will be of increased interest in the future since suitable calibration substances for casein polymers are scarce.

Natural organic matter (NOM) is a diverse blend of decomposed animal and plant material found in different natural water sources. Due to its large and complex structure, NOM is difficult to both remove and characterize in water. Therefore, there is a need to separate NOM into its components before it can be characterized. The aim of this project was to fractionate NOM through a novel size exclusion chromatography (SEC) composite (poly (styrene-divinyl benzene) (PS-DVB) and Polysilsesquioxane (PSQ)) packed column. Raw and final water samples from Mid-Vaal (MV), Olifantspoort (LO), Mtwalume (MT) and Preekstoel (P) were investigated. Poly (styrene-divinyl benzene) (PS-DVB) and polysilsesquioxane were both synthesized and optimized at various temperatures, compositions and time periods. An end-capping material such as hexamethyldisilizane (HMDS) was added on the PSQ to prevent active silanol groups on the polysilsesquioxane (PSQ) from reacting with active sites of NOM (our analyte). The E-PSQ (end-capped PSQ) and PS-DVB materials were packed in eight different SPE cartridges first, before the materials could be packed in the SEC column. This packing was done to check for the best mass composition of the E-PSQ and PS-DVB. From the obtained SPE results, both the EPSQ and PS-DVB were packed in one SEC/GPC column at a ratio of 1:1 in order to form the composite hybrid material. The packed SEC column was connected to an HPLC instrument and various column efficiency tests were evaluated. The results for the test of interactions with acidic compounds implied that the column can be used for the acidic analytes such as those forming NOM composition (humic acids, fulvic acids) and the column had minimum silanol groups. For hydrophobic interactions the stationary phase strength was different to that of the commercial columns and it could selectively elute molecules based on their different masses. The steric selectivity test showed that the stationary phase could separate and distinguish between molecules with similar hydrophobicity and structure but different shapes (o-terphenyl and triphenylene). The Hydrogen bonding capacity (HBC) test showed that the column had minimum silanol groups and the end-capping was successful on the E-PSQ. After fractionation of all the water samples, the MT raw showed NOM peaks around 1.8 mins, 3.4 mins and 5.3, and the final showed NOM peaks around 1.8 mins and 5.5 mins. The Mid-Vaal (MV) raw and final samples shows NOM peaks at around 1.8 mins and 6 mins. The Preekstoel (P) final water had one NOM peak at around 1.8 mins and raw samples had two NOM peaks around 1.8 mins and 6 mins. / Chemistry / M. Sc. (Chemistry)

Made available in DSpace on 2014-12-17T14:08:54Z (GMT). No. of bitstreams: 1 AliDGK_DISSERT.pdf: 1533034 bytes, checksum: 5570fc0acd3b2b8bab1dc04b3e8c619f (MD5) Previous issue date: 2014-01-29 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Modeling transport of particulate suspensions in porous media is essential for understanding various processes of industrial and scientific interest. During these processes, particles are retained due to mechanisms like size exclusion (straining), adsorption, sedimentation and diffusion. In this thesis, a mathematical model is proposed and analytical solutions are obtained. The obtained analytic solutions for the proposed model, which takes pore and particle size distributions into account, were applied to predict the particle retention, pore blocking and permeability reduction during dead-end microfiltration in membranes. Various scenarios, considering different particle and pore size distributions were studied. The obtained results showed that pore blocking and permeability reduction are highly influenced by the initial pore and particle size distributions. This feature was observed even when different initial pore and particle size distributions with the same average pore size and injected particle size were considered. Finally, a mathematical model for predicting equivalent permeability in porous media during particle retention (and pore blocking) is proposed and the obtained solutions were applied to study permeability decline in different scenarios / A modelagem do transporte de suspens?es em meios porosos ? essencial para o entendimento de diversos processos de interesse industrial e cient?fico. Durante esses processos as part?culas podem ser retidas devido a diferentes mecanismos, dos quais citamos: exclus?o pelo tamanho, adsor??o, sedimenta??o e difus?o. Neste trabalho, um modelo matem?tico para o mecanismo de exclus?o pelo tamanho foi proposto e solu??es anal?ticas foram encontradas. As solu??es anal?ticas para o modelo proposto, que incorpora as distribui??es de tamanho de poros e de part?culas, foram utilizadas para prever a reten??o de part?culas, o bloqueio de poros e a redu??o de permeabilidade durante a microfiltra??o direta (dead-end microfiltration) em membranas. Foram analisados diversos cen?rios, considerando diferentes distribui??es de tamanho de poros e de part?culas. Os resultados obtidos mostraram que o processo de bloqueio de poros e redu??o de permeabilidade ? fortemente influenciado pelas distribui??es iniciais de tamanho de poros e de part?culas. Esta caracter?stica foi observada mesmo quando diferentes distribui??es iniciais de tamanho de poros e de part?culas com um mesmo tamanho m?dio de part?culas e de poros foi considerado. Finalmente, um modelo matem?tico para a previs?o da permeabilidade equivalente em meios porosos durante a reten??o de part?culas (e bloqueio de poros) foi proposto e as solu??es obtidas foram aplicadas para o estudo do decl?nio da permeabilidade em diferentes cen?rios / 2020-01-01

La conversion de la biomasse lignocellulosique en biocarburants et molécules biosourcées produit des matrices liquides complexes thermosensibles qui couvrent une large gamme de polarités et de masses moléculaires. Les outils analytiques développés dans la littérature donnent une description partielle de ces matrices oxygénées. Pour en comprendre la réactivité et mieux guider le développement des procédés de conversion, une meilleure caractérisation est nécessaire. L’objectif de cette thèse est de démontrer l’apport d’une dimension de fractionnement pertinente en amont de techniques séparatives pour accéder à la caractérisation à l’échelle moléculaire d’échantillons ex-biomasse. Une déformulation complète et structurée par familles chimiques est visée, sans perte ni modification des composés. Deux voies de fractionnement ont été investiguées : (1) fractionnement par solubilité à l’aide de l’extraction liquide-liquide (LLE) et de la chromatographie de partage centrifuge (CPC) et (2) fractionnement par taille avec la chromatographie d’exclusion stérique (SEC). Ces techniques se veulent complémentaires à une analyse par chromatographie liquide à polarité de phase inversée avec détection par spectroscopie ultraviolet-visible et spectrométrie de masse haute résolution (RPLC-UV/HRMS). Des méthodes de fractionnement LLE, CPC et SEC ont été développées sur molécules modèles afin d’identifier les mécanismes et la sélectivité chimique mis en jeu. Des cartographies 2D inédites ont ainsi été obtenues, assurant un gain important en pouvoir résolutif et une structuration nouvelle des chromatogrammes en comparaison à l’approche RPLC-UV/HRMS. Dans un second temps, le potentiel des couplages SECxRPLC-UV/HRMS et CPCxRPLC-UV/HRMS pour la description de matrices complexes a été illustré via l’étude de deux échantillons issus d’expérimentations en unités pilotes et de compositions chimiques très différentes, représentant deux voies possibles de transformation (biochimique et thermochimique) de biomasse lignocellulosique. La complémentarité entre les approches de séparation mises au point a ainsi permis de doubler le nombre de pics détectés tout en bénéficiant de l’organisation chimique des composés. Cette aide précieuse à l’identification a été renforcée par les informations structurales délivrées via les différents modes de détection, en particulier l’HRMS. La compréhension de la structuration des cartographies 2D a été présentée et discutée afin de proposer la stratégie la plus adaptée pour déformuler complètement un échantillon en s’appuyant sur la mesure de descripteurs pertinents. Enfin, l’une des approches développée dans cette thèse a été mise en œuvre pour l’isolement sélectif et l’élucidation structurale de molécules clefs au sein d’une matrice complexe à l’aide d’expériences en fragmentation MS et spectroscopie de résonance magnétique nucléaire (RMN) / The conversion of lignocellulosic biomass into biofuels and biosourced molecules produces complex thermosensitive liquid matrices which cover a wide range of polarity and molecular weight. Analytical tools developed in the literature only give a partial description of these oxygenated matrices. To understand the reactivity of these samples and optimize the development of conversion processes, a better characterization is required. The objective of this thesis is to demonstrate the interest of a relevant fractionation step prior to separation techniques to help the molecular characterization of biomass samples. The reverse engineering proposed for the sample is desired complete and chemically controlled (without loss or sample modification). Two fractionation pathways were investigated: (1) solubility fractionation with liquid-liquid extraction (LLE) and centrifugal partition chromatography (CPC) and (2) size fractionation with size exclusion chromatography (SEC). These techniques intend to be complementary to reversed-phase liquid chromatography hyphenated to ultraviolet-visible spectroscopy detection and high resolution mass spectrometry (RPLC-UV/HRMS). LLE, CPC and SEC methods were developed on model molecules to understand mechanisms involved and control the chemical selectivity. 2D contour plots were obtained, improving the resolving power and structuring chromatograms in comparison with RPLC-UV/HRMS. Then, SECxRPLC-UV/MS and CPCxRPLC-UV/MS hyphenations were applied to describe two complex samples from different substrates produced on experimental pilot units from two possible conversion pathways of lignocellulosic biomass (biochemical and thermochemical). The complementarity of separation modes allows to double the number of peaks detected, benefiting from the chemical organization of compounds. This constitute a support to identification also enhanced by multi-detection which provide additional structural information on compound detected, especially HRMS. Chemical organization in 2D contour plots were presented and discussed to propose the most adapted strategy to fully fractionate a sample based on the measurement of relevant descriptors. Finally, one of the fractionation approach developed in this thesis was used to isolate and structurally elucidate key molecules of a complex sample through MS fragmentation experiments and nuclear magnetic resonance spectroscopy (NMR)

Enzymes are outstanding in their perfect 3D design through mastery of intrachain interaction of polypeptide chains. Seeking to mimic nature’s precision, a vibrant field in macromolecular science replicates natures pattern by the intrachain collapse of synthetic linear polymers to Single Chain Nano Particles (SCNPs) in the sub 30 nanometer realm. An in-depth understanding of the paradigms of intrachain collapse are largely missing, but urgently needed to exploit the potential of the versatile synthetic strategies for future applications. Therefore, present thesis focused on the in-depth investigation of SCNPs folding, performed via a powerful ligation strategy, e.g. the para-fluoro-thiol reaction (PFTR). The ligation reaction was subsequently transferred to light-triggered pathways with general utility in macromolecular science. The first part of the presented work focuses on the physicochemical transformations entailed in the intrachain-collapse of a pentafluorobenzyl (PFB) decorated SCNP precursor library. Statistically distributed PFB moieties enabled the implementation of powerful PFTR and thus, exploitation of sensitive 19F NMR spectroscopy. The precursor library was systematically modified in its reactive group density (5, 15, and 30 mol% PFB) and the absolute molar mass (20, 50, 100 kDa), enabling a screening of both impacts regarding the topology, the size and the conformation of the collapsed SCNPs. In function of these structural features, a comprehensive investigation was performed by a unique combination of small-angle neutron scattering (SANS), 19F NMR spectroscopy, and quadruple detection SEC (SEC-4D). Thus, parallel data evaluation from techniques with complementary physical principles was performed. In addition to detailed morphological insights, the primary factor dictating the compaction of SCNPs was determined by the reactive group density. The most effective and ineffective folding was found at ca. 30 mol% and below 5% reactive group density, respectively. Within these limits, the contraction can be fine-tuned by the molar mass, where very short precursor chains (20 kDa) indicated limits of conformational changes in in poor solvents. Unlocking the potential of flow-based separation techniques for the SCNP area, the current work demonstrated the successful fractionation of the SCNP library via asymmetrical flow field flow fractionation hyphenated to novel quintuple detection (AF4-D5) in organic solvents. Herein, SCNP formation was evidenced by a shift towards lower elution volumes for the SCNP respective the linear starting material, associated with the decrease of the hydrodynamic volume upon folding. The analysis using the complementary, conventional technique of column-based chromatography (SEC-D4) in the same solvent showed corresponding trends, which further validated the hydrodynamic collapse and enabled a comparative assessment of the separation performance of both separation techniques. The efficiency of SEC-D4 was compared to AF4-D5 in versatile foci, as the state-of the art detector coupling was applied to both advanced separation principles. The sophisticated detection provided an information rich data-library, refining the analysis of the structural changes affected by the internal folding process. An in-depth critical comparison of the derived sophisticated dataset was established and the advantages and limitations of both techniques, including instrumental considerations, were emphasized. The UV/Vis-based quantification of the PFB-ligated dithiol crosslinker as a function of the SCNPs hydrodynamic volume was highlighted. The comparison of the obtained molar mass moments, different types of radii and versatile descriptors of chain morphology validated the results obtained from neutron scattering experiments (SANS). Finally, the PFTR was transferred to light-triggered pathways with utility for the broad field of polymer chemistry. Using blue light irradiation, a photobase generator (PBG) effectively released the PFTR-activating superbase 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). After a model investigation with small molecules under high group tolerance, the light-induced PFTR enabled to graft versatile thiols on linear poly(styrene-co-pentafluorostyrene) copolymers in organic solvent (THF). Temporal control of the light-triggered PFTR was validated by time-resolved rheology experiments during network formation via light-induced PFTR. In summary, the current thesis provides a conceptual framework for SCNP design, based on the in-depth investigation of the paradigms dictating the intrachain collapse. Coherent parameters for a comparable platform of the description of the SCNP chain collapse were recommended. The scope of advanced methodologies for SCNP characterization was expanded to advanced flow-based separation techniques. Finally, light-triggered pathways of the PFTR were implemented and its utility for polymer design was presented. / Die beispiellose Perfektion in räumlicher Struktur und daher biochemischer Wirksamkeit von Proteinen beruht auf kontrollierter intramolekularer Wechselwirkung von Polypeptidketten. Die Nachahmung des intramolekularen Kollapses linearer Polymere zu verdichteten Single Chain Nanoparticles (SCNPs) im sub-30-Nanometer-Bereich entwickelte sich zu einem prosperierenden Feld in der Polymerchemie. Bis heute existiert noch kein tiefgreifendes Verständnis dieses Faltungsvorganges, welches jedoch dringend erforderlich ist, um das Potenzial der vielseitigen Synthesestrategien für zukünftige Anwendungen von SCNPs auszuschöpfen. Daher konzentrierte sich die vorliegende Arbeit auf die eingehende Untersuchung der SCNP-Faltung mittels effizienter intramolekularer Ligation via para-Fluor-Thiol-Reaktion (PFTR). Die PFTR wurde anschließend auf Licht-getriggerte Wege realisiert, welche in der makromolekularen Chemie von allgemeinem Nutzen sind. Der erste Teil der vorgestellten Arbeit konzentriert sich auf die umfassende Analyse der SCNP-Faltung und den damit verbundenen physikochemischen Veränderungen, die mit der intramolekularen PFTR-Ligation einer Vorläuferbibliothek einhergehen. Die Polymere der Bibliothek wurden systematisch in ihrer reaktiven Gruppendichte (5, 15 und 30 mol%) und der absoluten Molmasse (20, 50, 100 kDa) modifiziert, um Einflüsse beider Faktoren hinsichtlich der Topologie, der Größe und der Konformation der kollabierten SCNPs zu untersuchen. Der Umsatz der PFTR¬ an den statistisch verteilten Pentafluorbenzyl (PFB) Einheiten der SCNP-Vorläuferbibliothek wurde mittels sensitiver 19F-NMR-Spektroskopie quantifiziert. In Abhängigkeit der Strukturmerkmale der Vorläuferbibliothek wurde eine umfassende Analyse der physikochemischen Veränderungen durch eine bisher einzigartige Kombination von Kleinwinkel-Neutronenstreuung (SANS), 19F-NMR-Spektroskopie und SEC mit Vierfachdetektion (SEC-4D) durchgeführt. Der Einsatz von komplementären Analysetechniken ermöglichte eine fundierte Untersuchung des Polymerknäuel-Kollapses jenseits der gegenwärtigen methodischen Grenzen konventionell angewendeter Lichtstreutechniken durch zusätzliche Anwendung von Viskometrie und Kleinwinkel-Neutronenstreuung. Letztere zeigte durch ihr hohes räumliches Auflösungsvermögen einen Einblick auf die Segmenteigenschaften der polymeren Nanopartikel. Die morphologische Transformation von linearen Vorläufer-Polymeren zu verdichteten SCNP wurde vergleichend über die reaktive Gruppendichte evaluiert. Die Größenreduktion zu SCNPs ist bei einer reaktiven Gruppendichte von 30 Mol-% maximal, aber unter 5% kaum effektiv. Innerhalb dieser Grenzen ist eine sub-Kontrolle der Kontraktion durch die Variation der Molmasse möglich, wobei sehr kurze Vorläuferketten (20 kDa) die Grenze des noch möglichen Konformationswandels in schlechtem Lösungsmittel anzeigen. Weiterhin wurde erstmalig die erfolgreiche Fraktionierung der SCNP-Bibliothek mittels asymmetrischer Flussfeld-Flussfraktionierung (AF4) demonstriert, die mit einer neuartigen Kopplung zu Fünffach-Detektion (AF4-D5) mit organischem Eluenten angewendet wurde. Die Ergebnisse der Fraktionierung bestätigten die SCNP-Bildung durch das charakteristisch veränderte Elutionsverhalten des SCNP im Vergleich zum linearen Ausgangsmaterial, welches mit einer Verringerung des hydrodynamischen Volumens durch den Faltungsprozess zu erklären ist. Die Analyse mittels komplementärer, konventioneller Technik der säulenbasierten Chromatographie (SEC-D4) im gleichen Lösungsmittel zeigte dementsprechende Trends, was den hydrodynamischen Kollaps weiter validiert und eine vergleichende Bewertung der Trennleistung beider Separationstechniken ermöglichte. Modernste Vielfach-Detektion ermöglichte an beiden Separationstechniken (SEC und AF4) eine simultane und damit hocheffiziente Analyse. Dabei zeigte die AF4-basierte Separation eine teilweise verbesserte Trennung im Vergleich zur SEC. Die Vor- und Nachteile beider Techniken sowie instrumentelle Überlegungen wurden eingehend diskutiert. Die durch die Multidetektorkopplung erhaltenen Molmassenmomente, Größenparameter und vielseitige Deskriptoren der Kettenmorphologie der Fraktionen von beiden Seperationsmechanismen ermöglichten die umfassende Beschreibung der strukturellen Veränderungen während des Faltungprozesses. Diese Datensätze wurden mit den Ergebnissen der Neutronenstreuungsexperimente (SANS) und der Struktur der Vorläuferpolymere zu einem detaillierten Bild der Einflüsse des Faltungsprozesses korreliert. Die UV/Vis-basierte Quantifizierung des PFB-ligierten Dithiol-Vernetzers als Funktion des hydrodynamischen Volumens der SCNPs untermauerten zusätzlich die gewonnenen Erkenntnisse über die Struktur-Eigenschaft Beziehungen. Schließlich wurde die PFTR Ligation auf Licht-getriggerte Prozesse übertragen, welche für das breite Gebiet der Polymerchemie von Nutzen sind. Die effektive PFTR-aktivierende Base 1,8-Diazabicyclo [5.4.0] undec-7-en (DBU) wurde unter Verwendung von mittels blauem Licht getriggertem Photobase-Generator (PBG) effektiv freigesetzt. In der Untersuchung eines Modellsystems mit kleinen Molekülen wurde hohe Gruppentoleranz festgestellt und die lichtinduzierte PFTR ermöglichte die Pfropfung verschiedener Thiole an lineares Poly (styrol-co-pentafluorstyrol) in organischem Lösungsmittel (THF). Die zeitliche Kontrolle wurde durch zeitaufgelöste Rheologie Experimente während Netzwerkerzeugung via Licht-induzierter PFTR validiert. Zusammenfassend stellt die aktuelle Arbeit einen konzeptionellen Rahmen für SCNP-Design anhand genereller Paradigmen des Kettenkollapses bereit. Empfehlungen für kohärente Parameter zur Beschreibung des SCNP-Kettenkollapses wurden herausgearbeitet, die den Aufbau einer vielversprechenden Plattform für weitere, fortschrittliche SCNP-Forschung sind. Der Umfang geeigneter Methoden zur SCNP-Charakterisierung wurde auf Feldfluss-basierte Trenntechniken erweitert. Schließlich wurden licht-getriggerte Reaktionskaskaden der PFTR implementiert und ihre Nützlichkeit für das Polymerdesign von perflourierten Materialen vorgestellt.

Several novel polymer monoliths for the analysis of peptides and proteins were synthesized using polyethylene glycol diacrylate (PEGDA) as crosslinker. Photo-initiated copolymerization of polyethylene glycol methyl ether acrylate and PEGDA yielded an inert monolith that could be used for size exclusion liquid chromatography of peptides and proteins. This macroscopically uniform monolith did not shrink or swell in either water or tetrahydrofuran. More importantly, it was found to resist adsorption of both acidic and basic proteins in aqueous buffer without any organic solvent additives. A strong cation-exchange polymer monolith was synthesized by copolymerization of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) and PEGDA. A ternary porogen (water, methanol and ethyl ether) was found suitable to prepare a flow-through monolith with moderate pressure drop in aqueous buffer. The resulting monolith showed excellent ion exchange capillary liquid chromatography of peptides using a simple salt gradient. Extremely narrow peaks were obtained for the analysis of synthetic peptides, natural peptides and a protein digest. A peak capacity of 179 was achieved. Although the poly(AMPS) monolith demonstrated extraordinary performance, one main drawback of this monolith was its relatively strong hydrophobicity. A decrease in hydrophobicity was achieved by using more hydrophilic monomers (e.g., sulfoethyl methacrylate or vinyl sulfonic acid). The most hydrophilic poly(vinyl sulfonic acid) monolith provided high resolution cation-exchange liquid chromatography of protein standards and lipoproteins. Use of the new PEGDA biocompatible crosslinker over the conventional ethylene glycol dimethacrylate crosslinker for the preparation of polymer monoliths was found to be advantageous for the analysis of biological compounds in several chromatography modes.

La miniaturisation toujours plus poussée des composants électroniques a atteint une limite en arrivant à l’échelle atomique. Afin de fabriquer des circuits à cette échelle, il est nécessaire de intéresser aux plus petits composants pouvant être intégrés : les molécules individuelles et les groupes d’atomes. Dans cette optique, les molécules de 1,4-bis(pyridin-4-ylethynyl) benzène (BPEB), Dibenzo[a,h]thianthrene (DBTH), de Bis{82,92,152,162,222,232- hexa-(2,4,6-trifluorophenoxy)[g,l,q]-5,10,15,20-tetraazaporphyrino)}[b,e]-benzene (H4Pc2) ont été conçues, synthétisées et caractérisées afin d’en étudier le transport de charges et les changements induits proche de la surface. Des techniques de SPM, tels que le STM, le nc-AFM et l’usage conjoint de l’AFM avec le STM ont été mises en pratique pour analyser les molécules reposant intégralement ou partiellement sur un substrat. L’interprétation des résultats expérimentaux a été faite au moyen de calculs de DFT. De plus, l’autoassemblage en solution de nouvelles mono-phthalocyanines métalliques fluorées, MPc (M= Mg2+, 2H+, Co2+) a été étudié.Tout d’abord, les mesures de conductance mirent en évidence, lors d’expériences de manipulation de fils moléculaires (BEPB), les changements de conformation associés aux transport des électrons à travers les molécules. De plus, le mouvement dit de “retournement papillon” (anglais: butterfly flapping) ayant lieu dans la classe des thianthrènes fut bloqué à basse température grâce à l’interaction avec le substrat. Ce blocage a permit de conduire la première étude stéréochimique de dérivés de thianthrènes chiraux (DBTH). Les analyses STM du DBTH ont montrées que le passage entre deux configurations de DBTH est reproductible et non-destructif. Par ailleurs, le nc-AFM utilisé à résolution sub-moléculaire a constitué un outils important pour réaliser une caractérisation complète et distinguer entre les différents isomères de configuration et de constitution déposés sur une surface. D’autre part, la structure moléculaire de la phthalocyanine binucléaire (H4Pc2) a été confirmée en utilisant un STM en mode “courant constant” et un AFM en mode “fréquence constante”. Ces résultats jettent les bases d’une prochaine étude de transport (travail en cours). En outre, l’étude de l’agrégation dans les molécules de MPc mit en évidence le rôle important de la capacité de coordination de l’atome central de la cavité Pc sur la formation d’agrégat. Finalement, des mesures électrochimiques ont démontrées que l’agrégation moléculaire peut bloquer le nature active de l’atome Co2+. Dans ce travail, il a été clairement montré que le SPM est une technique adéquate pour étudier les changements de conformations et de configurations associés aux courant tunnel d’électrons à travers des molécules, qu’elles soient planaire ou pas. Les études d’agrégation des interrupteurs magnétiques ont permis de mieux comprendre l’organisation supramoléculaire. Cette organisation est un point crucial pour le développement de futurs circuits basés sur une fabrication “bottom-up”. / The demand of downscaling of technology will reach its limit at the atomic length scale. This claim creates the necessity of investigating the smallest components suitable to become devices, single molecules or group of atoms. Therefore, 1,4-bis(pyridin-4-ylethynyl) benzene (BPEB), Dibenzo[a,h]thianthrene (DBTH) and Bis{82,92,152,162,222,232-hexa-(2,4,6-trifluorophenoxy)[g,l,q]-5,10,15,20-tetraazaporphyrino)}[b,e]-benzene (H4Pc2) have been designed, synthesized and characterized to investigate transport of charge through molecules and surface confined molecular switching. Scanning Probe Microscopy (SPM), such as STM, nc-AFM and combined STM/AFM were used to study the molecules on near-surface conditions. Density Functional Theory (DFT) calculations were used to interpret the experimental results. Moreover, the self-assembly of new fluorinated metalo mono-phthalocyanines, MPc (M= Mg2+, 2H+, Co2+) was investigated in solution.Firstly, conductance experiments performed while a molecular wire (BPEB) was being lifted up from a surface revealed the conformational changes associated to the transport of electrons through molecules. Secondly, the “butterfly” flapping motion in the class of the thianthrenes was blocked due to the interaction with a surface at low temperature. This block leads to the first stereochemical study of a quiral thianthere derivative (DBTH). The STM experiments on DBTH revealed a reproducible and non-destructive switching between two surface confined configurations of DBTH. In addition, nc-AFM with submolecular resolution has been proved to be a powerful tool for the full characterization and distinction of configurational and constitutional isomers on surfaces. Thirdly, the molecular structure of a binuclear phthalocyanine (H4Pc2) was confirmed through constant current STM and constant high _f AFM experiments. These results set the state of future spintronic transport experiments (ongoing work). On the other hand, the aggregation studies on MPc revealed that the coordination character of the central atom of the Pc cavity has an important effect on the formation of aggregates. Additionally, electrochemical experiments demonstrated that molecular aggregations can lead to the quenching of the electrochemical-active nature of a Co2+ atom.Herein it has been demonstrated that SPM are suitable techniques to study the conformational and configurational changes associated with the tunneling of electrons through planar and non-planar molecules in real space. Aggregation studies of magnetic switches were carried out to better understand the supramolecular organization under near surface conditions, a key point for the design of future devices based on the bottom up approach.