Les nitrones peuvent être réduites par le diiodure de samarium et réagir selon une additionconjuguée avec des acrylates-silylés, silylés ou ,disilylés. Ce couplage réducteur,développé avec des aldonitrones simples, a conduit à des dérivés silylés de g-Nhydroxyaminoacides.Ces derniers ont pu être réduits puis cyclisés en g-lactames substituéspar un groupement silylé, dont la position et la configuration dépendent de l'acrylate dedépart. L'oxydation de Tamao-Fleming a ensuite permis la conversion des composés silylésen leurs correspondants hydroxylés avec rétention de configuration. Cet enchaînementréactionnel a alors été appliquée à une nitrone cyclique polyalkoxylée dérivée du L-xylose, cequi a permis les synthèses de la 7-desoxy Uniflorine A et de la (+)-Australine, deuxpyrrolizidines polyhydroxylées inhibiteurs de glucosidases.

Made available in DSpace on 2014-06-11T19:35:46Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-01-11Bitstream added on 2014-06-13T18:47:18Z : No. of bitstreams: 1 urban_vm_dr_arafo.pdf: 2869944 bytes, checksum: e7264bf2de7fc0a0dde924482741fd32 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Os objetivos deste estudo foram avaliar: 1. o efeito de tratamentos póspolimerização (MW-irradiação por energia de microondas e WB-imersão em água aquecida) sobre o grau de conversão (DC) de resinas acrílicas para reembasamento imediato (Ufi Gel hard-U, Kooliner-K e Tokuso Rebase Fast-T) e de uma resina acrílica para base de prótese (Lucitone 550-L), submetida a dois ciclos de polimerização (LS-curto e LL-longo) por espectroscopia FT-Raman; 2. o peso molecular (M w) do pré-polímero dos materiais U, K, T e L e das amostras polimerizadas da resina K (controle; MW e WB) por GPC; 3. o efeito de MW e WB na temperatura de transição vítrea (Tg) das resinas para reembasamento imediato (Duraliner II-D, K, New Truliner-N, U e T) e da resina para base de prótese (LS e LL) por DSC; 4. o efeito de WB na liberação de compostos residuais (isobutil metacrilato-IBMA, 1,6-hexanediol dimetacrilato-1,6-HDMA e DBNP-dibutil-n-ftalato) a partir das resinas para reembasamento imediato K, N, U e T para saliva artificial por CLAE; 5. o efeito de WB na liberação de produtos de degradação (ácido metacrílico-MA e ácido benzóico-BA) a partir das resinas para reembasamento imediato K, N, U e T para saliva artificial por CLAE. Amostras do grupo controle não foram submetidas a nenhum tratamento. Os resultados de DC (%) foram analisados pelo teste de Kruskal-Wallis ( =0,05). Os resultados de Tg (ºC) foram analisados pela análise de variância (ANOVA), seguido pelo teste de Tukey ( =0,05). Os resultados da liberação de monômero ' 224 residual e plastificante (μg/mL) foram submetidos aos testes de Wilcoxon ou de Mann-Whitney ( =0,05). Os resultados da liberação de produtos de degradação (μg/mL) foram submetidos aos testes de Wilcoxon, Mann-Whitney ou Kruskal- Wallis ( =0,05). Para as amostras do grupo controle, não houve diferenças significantes entre o DC das resinas U e LL e entre... / The aims of this study were to evaluate: 1. the effect of post-polymerization treatments (MW-microwave irradiation and WB-water-bath) on the degree of conversion (DC) of reline resins (Ufi Gel hard-U, Kooliner-K, and Tokuso Rebase Fast-T) and denture base resin (Lucitone 550-L), submitted to two polymerization cycles (LS-short and LL-long) by FT-Raman spectroscopy; 2. the molecular weight (M w) of the powder of U, K, T, and L materials and of K polymerized specimens (control; MW; and WB) by GPC; 3. the effect of MW and WB on the glass transition temperature (Tg) of the reline resins (Duraliner II-D, K, New Truliner-N, U and T) and the heat-polymerized resin (LS and LL) by DSC; 4. the effect of WB on the leaching of residual compounds (isobutyl methacrylate- IBMA, 1,6-hexanediol dimethacrylate-1,6-HDMA, and DBNP-dibutyl-nphthalate) from the reline resins (K, N, U, and T) in artificial saliva by HPLC; 5. the effect of WB on the leaching of degradation products (methacrylic acid-MA and benzoic acid-BA) from the reline resins K, N, U, and T in artificial saliva by HPLC. Control group specimens were left untreated. DC (%) data were analyzed using Kruskal-Wallis test (_=.05). Tg (ºC) data were analyzed using ANOVA/Tukey's test (_=.05). The results (æg/mL) of residual monomer and plasticizer leachability were submitted to Wilcoxon or Mann-Whitney tests (_=.05). The results (æg/mL) of degradation products leachability were submitted to Wilcoxon, Mann-Whitney or Kruskal-Wallis tests (_=.05). For DC control specimens, there were no significant differences between U and LL and among LL, K, and T. LS specimens had the highest DC. Only material K exhibited an increased DC after WB. All powders had M w from 4.0x105 to 6.5x105 and narrow M w distributions (2.1 to 3.6). Polymerization and post-polymerization produced K specimens with M w values similar to that of K powder...(Complete abstract, click electronic address below).

Resumo: Os objetivos deste estudo foram avaliar: 1. o efeito de tratamentos póspolimerização (MW-irradiação por energia de microondas e WB-imersão em água aquecida) sobre o grau de conversão (DC) de resinas acrílicas para reembasamento imediato (Ufi Gel hard-U, Kooliner-K e Tokuso Rebase Fast-T) e de uma resina acrílica para base de prótese (Lucitone 550-L), submetida a dois ciclos de polimerização (LS-curto e LL-longo) por espectroscopia FT-Raman; 2. o peso molecular (M w) do pré-polímero dos materiais U, K, T e L e das amostras polimerizadas da resina K (controle; MW e WB) por GPC; 3. o efeito de MW e WB na temperatura de transição vítrea (Tg) das resinas para reembasamento imediato (Duraliner II-D, K, New Truliner-N, U e T) e da resina para base de prótese (LS e LL) por DSC; 4. o efeito de WB na liberação de compostos residuais (isobutil metacrilato-IBMA, 1,6-hexanediol dimetacrilato-1,6-HDMA e DBNP-dibutil-n-ftalato) a partir das resinas para reembasamento imediato K, N, U e T para saliva artificial por CLAE; 5. o efeito de WB na liberação de produtos de degradação (ácido metacrílico-MA e ácido benzóico-BA) a partir das resinas para reembasamento imediato K, N, U e T para saliva artificial por CLAE. Amostras do grupo controle não foram submetidas a nenhum tratamento. Os resultados de DC (%) foram analisados pelo teste de Kruskal-Wallis ( =0,05). Os resultados de Tg (ºC) foram analisados pela análise de variância (ANOVA), seguido pelo teste de Tukey ( =0,05). Os resultados da liberação de monômero ' 224 residual e plastificante (μg/mL) foram submetidos aos testes de Wilcoxon ou de Mann-Whitney ( =0,05). Os resultados da liberação de produtos de degradação (μg/mL) foram submetidos aos testes de Wilcoxon, Mann-Whitney ou Kruskal- Wallis ( =0,05). Para as amostras do grupo controle, não houve diferenças significantes entre o DC das resinas U e LL e entre...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The aims of this study were to evaluate: 1. the effect of post-polymerization treatments (MW-microwave irradiation and WB-water-bath) on the degree of conversion (DC) of reline resins (Ufi Gel hard-U, Kooliner-K, and Tokuso Rebase Fast-T) and denture base resin (Lucitone 550-L), submitted to two polymerization cycles (LS-short and LL-long) by FT-Raman spectroscopy; 2. the molecular weight (M w) of the powder of U, K, T, and L materials and of K polymerized specimens (control; MW; and WB) by GPC; 3. the effect of MW and WB on the glass transition temperature (Tg) of the reline resins (Duraliner II-D, K, New Truliner-N, U and T) and the heat-polymerized resin (LS and LL) by DSC; 4. the effect of WB on the leaching of residual compounds (isobutyl methacrylate- IBMA, 1,6-hexanediol dimethacrylate-1,6-HDMA, and DBNP-dibutyl-nphthalate) from the reline resins (K, N, U, and T) in artificial saliva by HPLC; 5. the effect of WB on the leaching of degradation products (methacrylic acid-MA and benzoic acid-BA) from the reline resins K, N, U, and T in artificial saliva by HPLC. Control group specimens were left untreated. DC (%) data were analyzed using Kruskal-Wallis test (_=.05). Tg (ºC) data were analyzed using ANOVA/Tukey's test (_=.05). The results (æg/mL) of residual monomer and plasticizer leachability were submitted to Wilcoxon or Mann-Whitney tests (_=.05). The results (æg/mL) of degradation products leachability were submitted to Wilcoxon, Mann-Whitney or Kruskal-Wallis tests (_=.05). For DC control specimens, there were no significant differences between U and LL and among LL, K, and T. LS specimens had the highest DC. Only material K exhibited an increased DC after WB. All powders had M w from 4.0x105 to 6.5x105 and narrow M w distributions (2.1 to 3.6). Polymerization and post-polymerization produced K specimens with M w values similar to that of K powder...(Complete abstract, click electronic address below). / Orientador: Ana Lucia Machado / Coorientador: Quezia Bezerra Cass / Banca: Carlos Eduardo Vergani / Banca: Carlos Alberto dos Santos Cruz / Banca: Marcelo Ferraz Mesquita / Banca: Regina Vincenzi Oliveira / Doutor

L’objectif principal de cette thèse était de comprendre par une approche conjointe théorie/expérience des réactions de polymérisation de monomères polaires, plus particulièrement de dérivés (méth)acryliques, réactions organocatalysées par des carbènes N-Hétérocycliques (NHC) utilisés seuls ou associés à une molécule organique (alcool) ou à un acide de Lewis. Pour cela un travail de rationalisation des effets électroniques et stériques apportés par le carbène a été réalisé à la fois sur les premières étapes du mécanisme de polymérisation par la théorie de la fonctionnelle de la densité (DFT) mais également sur les mécanismes potentiellement concurrents (cyclo-dimérisation) par deux méthodes théoriques: la DFT et la dynamique moléculaire (MD). L’ajout d’une molécule tierce comme un alcool ou un acide de Lewis (borane ou silane) a également été étudié théoriquement en détail afin de mieux comprendre l’effet de cette association sur la nature du mécanisme privilégié et sur l’efficacité de la polymérisation. / The main objective of this thesis was to understand, by a joint theoretical/experimental approach, polymerization reactions of polar monomers, especially (meth)acrylic derivatives, organocacatalyzed polymerizations by N-Heterocyclic carbenes (NHC) used alone or in combination with an organic molecule (alcohol) or a Lewis acid. Rationalization of both electronic and steric effects of the carbene was performed on the first steps of the polymerization mechanism by the functional density theory (DFT) and also on potentially competitive mechanisms (cyclodimerization) by two theoretical methods: DFT and molecular dynamics (MD). The addition of a third molecule such as an alcohol or a Lewis acid (borane or silane) has also been theoretically studied in detail in order to better understand the effect of this association on the nature of the privileged pathway and the effectiveness of the polymerization.

This research investigates the synthesis and manufacture of shape-memory polymer (SMP) systems for use in biomedical and commodity applications. The research centers on improving the mechanical properties of thermoset acrylate copolymers with memory properties at reasonable cost through various design and manufacturing techniques: high-strain polymer synthesis and radiation crosslinking. The research assesses combinations of linear monomers and a low density of crosslinker to characterize new functional materials and optimize emerging mechanical properties such as the glass transition temperature (Tg) and rubbery modulus (ER). Exploring materials with large recoverable strains, a model copolymer of photo-polymerized methyl acrylate (MA), isobornyl acrylate and crosslinker bisphenol A ethoxylate dimethacrylate was shown to strain above 800%, twice the previously published value for SMPs, and recover fully. In the quest to maximize fully recoverable strains, a new hybrid molecule nicknamed Xini, which serves as both an initiator and a crosslinker, was also theorized, synthesized, polymerized into SMP networks and characterized. In the past, thermoset SMPs were made into complex shapes using expensive top-down techniques. A block of polymer was made and custom machining was required to craft complex parts. This prohibited devices in cost-competitive commodity application spaces. This research has proposed and validated a new method for accurately tuning the thermomechanical properties of network acrylates with shape-memory properties: Mnemosynation, eponymously named for the Greek goddess of memory. This novel manufacturing process imparts long term 'memory' on an otherwise amorphous thermoplastic material utilizing radiation-induced covalent crosslinking, and can be likened to Vulcanization, which imparts strength on natural rubber utilizing sulfur crosslinks. Adjustment of ER in the range from below 1 MPa to above 13 MPa has been demonstrated. ER was tailored by varying both radiation dose between 5 and 300 kGy and crosslinker concentration between 1.00 and 25.0 wt%. Tg manipulation was demonstrated between 23 ˚C and 70 ˚C. Mnemosynation combines advances in radiation grafting and acrylic SMP synthesis to enable both traditional plastics processing (blow molding, injection molding, etc.) and control of thermoset shape-memory properties. Combining advances in both high strain polymer synthesis and radiation crosslinking, a new paradigm in SMP composites manufacture-namely, that materials can be designed to enhance strain capacity at moderate stress, rather than maximum strength-was established. Various fibers with very different mechanical properties were impregnated with SMPs and thermo-mechanically assessed to develop an understanding of the technical parameters necessary to craft self-adjusting, multi-actuated, SMP-fiber composite orthopedic casts. This exploration syncs with the overarching aim of the research, which is to understand the fundamental scientific drivers necessary to enable new devices mass-manufactured from acrylate copolymers and optimize their emerging mechanical properties.

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Η κρυστάλλωση και η διάλυση αλάτων αποτελούν σημαντικές διεργασίες οι οποίες συνεισφέρουν στην φθορά των μνημείων της πολιτιστικής μας κληρονομιάς, τα οποία έχουν κατά κύριο λόγο κατασκευασθεί από δομικά υλικά όπως ο ασβεστόλιθoς και το μάρμαρο. Η κρυστάλλωση ευδιάλυτων αλάτων (π.χ. θειϊκό νάτριο, θειϊκό μαγνήσιο, χλωριούχο νάτριο) σε πορώδη υλικά έχει καταστροφικές επιπτώσεις τόσο στις ιστορικές όσο και στις σύγχρονες κατασκευές από σκυρόδεμα. Το πιο κατεστρεπτικό άλας για την ακεραιότητα των κατασκευών έχει αποδειχθεί, ότι είναι το θειίκό νάτριο. Η κατανόηση του μηχανισμού κρυστάλλωσης του άλατος αυτού είναι απαραίτητη προϋπόθεση για τον περιορισμό ή τον έλεγχο του σχηματισμού του σε ατμοσφαιρικές συνθήκες. Για τον σκοπό αυτό, έγινε συστηματική μελέτη της κρυσταλλικής ανάπτυξης του δεκαένυδρου θειϊκού νατρίου (Μιραμπιλίτης) σε υπέρκορα διαλύματά του. Αναπτύχθηκε μεθοδολογία βασισμένη στον εξώθερμο χαρακτήρα της κρυσταλλικής ανάπτυξης του μιραμπιλίτη. Η πειραματική μελέτη περιορίσθηκε στην ετερογενή κρυσταλλική ανάπτυξη τόσο σε φύτρα Μιραμπιλίτη, όσο και σε ξένα υποστρώματα. Τα υποστρώματα τα οποία μελετήθηκαν περιλάμβαναν ασβεστόλιθο από την Γρανάδα (ασβεστιτικός κυρίως) καθώς και ψαμμόλιθο (Πράγα, Τσεχίας) πυριτικής κατά κύριο λόγο σύστασης. Η μελέτη της κινητικής της κρυσταλλικής ανάπτυξης του Μιραμπιλίτη, έδειξε ότι το καθορίζον την ταχύτητα στάδιο είναι η διάχυση των δομικών μονάδων στην επιφάνεια των κρυσταλλικών φύτρων του Μιραμπιλίτη. Το συμπέρασμα αυτό οδήγησε στην δοκιμή οργανοφωσφορικών ενώσεων, ως προς την επίδρασή τους στην κινητική της κρυσταλλικής ανάπτυξης του μιραμπιλίτη. Οι ενώσεις αυτές ιονίζονται και αλληλεπιδρούν αποτελεσματικά με την κρυσταλλική επιφάνεια δηλητηριάζοντας τα ενεργά κέντρα κρυστάλλωσης. Ο βαθμός ιονισμού βρέθηκε ότι είναι καθοριστικός για την ανασταλτική τους δράση. Πειράματα ταχείας καταβύθισης ευδιάλυτων αλάτων ηλεκτρολυτών σε ασβεστολιθικά και ψαμμιτικά δοκίμια τα οποία έγιναν τόσο με εμβάπτιση, όσο και με έκθεση σε θάλαμο αλατονέφωσης επιβεβαίωσαν τα αποτελέσματα της μελέτης της κινητικής της κρυστάλλωσης του Μιραμπιλίτη και της σχετικής αποτελεσματικότητος των αναστολέων που χρησιμοποιήθηκαν. Πλην της κρυσταλλικής ανάπτυξης ευδιάλυτων αλάτων, σημαντική συνεισφορά στην αποδόμηση των δομικών υλικών παίζει και η διάλυση του ανθρακικού ασβεστίου, το οποίο και αποτελεί τη βασική συστατική τους ένωση. Για τη μελέτη της διεργασίας της κρυσταλλικής ανάπτυξης και διάλυσης του ανθρακικού ασβεστίου τόσο απουσία όσο και παρουσία ανιόντων όπως τα θειϊκά και τα ανιόντα φθορίου χρησιμοποιήθηκε η μικροσκοπία ατομικής δύναμης,η οποία έδωσε την δυνατότητα in situ μέτρησης του ρυθμού κρυσταλλικής ανάπτυξης και διάλυσης σε συνθήκες σταθερού κορεσμού. Η παρουσία θειϊκών ανιόντων έδειξε ότι η κρυσταλλική ανάπτυξη του ανθρακικού ασβεστίου αναστέλλεται ενώ η παρουσία φθορίου επιταχύνει τη διάλυση. Τα αποτελέσματα των μετρήσεων της κινητικής των διεργασιών έδειξαν ότι οι επιμολύνσεις στα υπέρκορα διαλύματα δρούν στην κινητική λόγω προσρόφησης και δέσμευσης των ενεργών κέντρων κρυσταλλικής ανάπτυξης διάλυσης. / The research made in the present PhD Thesis entitled “Crystallization and dissolution study of electrolyte salts”. The objective of the dissertation concerned both crystallization and dissolution processes of soluble sodium sulfate and insoluble calcium carbonate electrolyte salts approached by different experimental aspects but directly connected to environmental and scientific issues. Salt crystallization is an important cause for the weathering and damage of historical and cultural heritage artifacts and ornamental stones. Soluble salts (i.e. sodium sulfate, magnesium sulfate, sodium chloride) have also a damaging and fateful impact on civil engineering structures of roads and building foundations. Most damaging salt for such built frameworks is proven to be sodium sulfate salt. Only when we have a better understanding of sodium sulfate crystallization in an unconstrained fluid medium can we progress to a study of sodium sulfate crystallization in porous building materials. At the beginning of this study batch crystallization experiments of sodium sulfate salt were conducted. Additionally potential organic inhibitors (i.e. organophosphonate, polyacrylates) were tested in the same batch experimental system. Popular and applicable limestone building material is of uniform composition consisting mainly calcium (calcitic material). Granada’s calcarenite has been selected as one of the target material to study. This natural stone is representative of the building material utilized in construction material monuments and susceptible to salt crystallization. In situ AFM experiments of both calcite crystal growth and dissolution were performed in the presence of different electrolyte solutions (i.e. sodium sulfate and sodium fluoride). Nanoscale phenomena during the growth of solid solutions on calcite surfaces were performed in the presence of sodium sulfate electrolyte solutions. Further molecular-scale surface processes during both growth and dissolution of calcite in the presence of sodium fluoride electrolyte solutions were carried out. In all cases significant kinetic data and reaction mechanisms were extracted. Accelerated degradation of Granada’s limestone and Czech sandstone experiments were executed. Tested materials were exposed and impregnated in concentrated solutions of soluble salts (i.e. sodium sulfate, magnesium sulfate and sodium chloride). Immersed limestone type material showed susceptibility to sodium sulfate and sandstone type material to sodium chloride salt solution. Different pre-treatments of limestone specimens with organophosphonate compounds resulted in limiting material damage from sodium sulfate influence. The use of such organic compounds may direct towards a potential implication of conserving building frameworks. Finally suspended limestone rods were subjected to sodium sulfate spray chamber. Pre-treatment of limestone rods with organophosphonate compounds were completed. Again applications of organophosphonate compounds to exposure of limestone material in salt spray chamber may work towards a case of preventing porous material from salt damage and protect building stones.

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No description available.