Surface behavior of poly (epsilon-caprolactone) (PCL) have been studied at the air/water interface (A/W). PCL is a hydrophobic and crystalline polyester with a glass transition temperature around -60 degrees centigrade, a melting point around 55 degrees centigrade, excellent biocompatibility, and low toxicity. In the past decade, PCL based systems have attracted considerable interest for controlled-release drug delivery and as scaffolds for tissue engineering, that require a fundamental understanding of PCL's degradation mechanisms and crystallization properties. PCL spherulites were commonly observed in previous bulk studies. This thesis focuses on PCL crystallization in Langmuir monolayers. Brewster angle microscopy (BAM) studies show that square, distorted rectangular, and dendritic crystals form at the A/W interface. While dendritic structures have been observed in poly (ethylene oxide) (PEO) thin film on solid substrates, this study of PCL is the first time that dendritic morphologies have been observed at the A/W interface for a linear flexible-coil polymer. As far as we know, the crystallization of flexible-coil polymers at the A/W interface is a brand new area of research. These findings may provide an interesting model system for studying crystallization in confined geometries and the effect of crystallinity on enzyme catalyzed hydrolysis of this important biodegradable polymer at the A/W interface. The main objectives of this thesis were to investigate the phase behavior of PCL at the A/W interface, gain a deeper understanding of the nucleation and growth mechanism of PCL crystallization at the A/W interface through surface pressure-area isotherms and isobaric area relaxation analyses, and interpret the effects of molecular weight on the nucleation and growth mechanism, and morphologies of semicrystalline PCL crystallized in Langmuir monolayers at the A/W interface. / Master of Science

Grafenoxid (GO) ar en lovande kandidat som nano-tillsats i medicinska byggnadsstallningar for benregenerering. GO kan forbattra den biologiska kompatibiliteten och osteogena prestandan hos polymerbaserade byggstallningar, och ocksa vasentligt bidra till forbattringen av materialets mekaniska egenskaper. I detta arbete ympades nano-grafenoxid (nGO) kovalent pa ytan av poly (e-kaprolakton) (PCL) genom att fdrst modifiera polymerytan via aminolys. Med anvandning av 1,6-hexandiamin / isopropanol infordes fria amingrupper framgangsrikt pa PCL-ytan for efterfoljande immobilisering av nGO. En optimerad ympningsprocess utvecklades via en losningsmedelsassisterad metod med vatten som losningsmedel for att kovalent binda nGO pa ytan av PCL byggnadsstallningar. De initiala nGO koncentrationerna var 0,5 och 1 mg / ml. fourier-transform infrarodspektroskopi (FTIR) och termogravimetrisk analys (TGA) verifierade bindningen mellan de funktionella gruppema pa nGO och de fria aminema. Svepelektronmikroskopi (SEM) visade en homogen fordelning av nGO pa ytan av de porosa byggnadsstallningarna. De mekaniska testema som utfordes demonstrerade · en 50 och 21 % okning av kompressionsstyrkan :for byggnadsstallningarna ympade med de initiala nGO-koncentrationema pa 0,5 och 1 mg / ml. In vitro-mineraliseringstester visade bildandet av mineralfallningar pa ytan av byggnadsstallningama som okade i storlek med hogre nGO-halt. A ven nGO: s potential som nano-barare av ett antibiotikum studerades i detta arbete. Pa grund av sitt overflod av kemiska funktionaliteter kan nGO effektivt adsorbera foreningar genom olika sekundara interaktioner. I denna studie optimerades dessa sekundara interaktioner genom att reglera losningens pH for maximal adsorption av ciprofloxacin, ett bredspektrum antibiotikum som anvands vid behandling av osteomyelit. Ciprofloxacin befanns kunna adsorberas starkast i sin katjonform vid pH 5, dar 1t-1t elektron­donatoracceptor (EDA) -interaktioner dominerar. Sammanfattningsvis bekraftar de resultat som presenteras i detta arbete potentialen hos nGO som egenskapsforbattrare och lakemedelsbarare i applikationer inom vavnadsregenerering. / Graphene oxide (GO) is a promising candidate as nano-filler material in scaffolds for bone regeneration. It has been demonstrated to enhance the biological compatibility and osteogenic performance of polymer-based scaffolds, aside from its substantial contribution to the improvement of the material's mechanical properties. In this work, nano-graphene oxide (nGO) was covalently grafted to the surface of poly( e-caprolactone) (PCL) by first modifying the polymer surface via aminolysis. Using 1,6-hexanediamine/isopropanol, free amine groups were successfully introduced to the PCL surface for the subsequent immobilization of nGO. An optimized grafting pathway, which implements the solvent-assisted method and uses water as a solvent, was developed to covalently attach nGO using initial concentrations of 0.5 and 1 mg/mL. Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) both verified the successful attachment of nGO through the free amines. Scanning electron microscopy (SEM) depicts a homogeneous dispersion of nGO over the polymer matrix. Mechanical tests were performed and demonstrate a 50 and 21 % increase in compressive strength for the scaffolds grafted using initial nGO concentrations of 0.5 and 1 mglmL. In vitro mineralization tests showed the formation of mineral precipitates on the surface of the scaffolds that increased in size with higher nGO content. The potential of nGO as a nano-carrier of an antibiotic drug was also explored in this work. As it comprises of an abundance of chemical functionalities, nGO is able to efficiently adsorb compounds through various secondary interactions. In this study, these secondary interactions were optimized by controlling the solution pH for the maximum adsorption of ciprofloxacin, a broad-spectrum antibiotic used in the treatment of osteomyelitis. Ciprofloxacin was found to be adsorbed most strongly in its cationic form at pH 5, in which 1t-1t electron-donor acceptor (EDA) interactions predominate. Overall, the results presented in this work validate the potential of nGO as nano-enhancer and drug carrier in tissue engineering scaffold applications.

Ce travail de thèse décrit l'élaboration de copolymères amphiphiles obtenus par couplage de deux homopolymères. La synthèse des copolymères s'est effectuée en deux étapes. Dans un premier temps, des homopolymères de type poly(2-méthyl-2-oxazoline) (P(MOx)) et poly(acrylate de tert-butyle) (P(At-Bu)) ont été préparés par polymérisation par ouverture de cycle cationique (CROP) et par polymérisation radicalaire contrôlée de type RAFT ou ATRP, respectivement. Puis les copolymères amphiphiles diblocs ont finalement été obtenus par une réaction de couplage polymère-polymère de type cycloaddition de Huisgen. Une étude physico-chimique de ces copolymères dans l'eau a mis en évidence la présence d'agrégats qui présentent une morphologie sphérique, des tailles inférieures à 100 nm et des concentrations d'agrégation critique de l'ordre de 10-6 mol.L-1.Les connaissances acquises sur la synthèse et l'étude des copolymères à blocs amphiphiles ont également permis le développement de copolymères greffés amphiphiles poly(-caprolactone)-g-poly(2-méthyl-2-oxazoline) (PCL-g-P(MOx)), constitués d'un bloc hydrophobe PCL sur lequel des chaînes hydrophiles P(MOx) ont été greffées. L'étude du comportement de ces copolymères dans l'eau montre la formation d'agrégats avec des caractéristiques proches de celles obtenues pour les copolymères diblocs amphiphiles. Un autre point intéressant est que la P(MOx) permet de solubiliser la PCL dans l'eau.Ces deux études illustrent l'apport de la chimie macromoléculaire pour la préparation de structures amphiphiles parfaitement définies qui s'organisent en phase aqueuse en agrégats. Ces derniers pourraient notamment être utilisés dans le domaine biomédical. / This manuscript deals with the synthesis of amphiphilic diblock copolymers obtained by the coupling of both hydrophobic and hydrophilic homopolymers. The copolymers were achieved in two steps. On the one hand, homopolymers poly(2-methyl-2-oxazoline) P(MOx)s and poly(tert-butyl acrylate)s (P(At-Bu) were synthesized by cationic ring opening polymerization (CROP) and by Reversible Addition-Fragmentation Transfer (RAFT) polymerization and atom transfer radical polymerization (ATRP), respectively. Finally, amphiphilic diblock copolymers were achieved by Huisgen's cycloaddition. Physical chemistry studies in water proved the formation of aggregates. The latter had a spherical morphology, sizes below 100 nm and critical aggregation concentration around 10-6 mol.L-1.Knowledge acquired on the synthesis and the study of amphiphilic block copolymers led to the development of poly(-caprolactone)-g-poly(2-methyl-2-oxazoline) (PCL-g-P(MOx)) amphiphilic graft copolymers, made of a hydrophobic PCL grafted with hydrophilic P(MOx) moieties. The study of aqueous solution of such copolymers showed the formation of aggregates with characteristics close from those obtained for the diblock copolymers. Another interesting point is that P(MOx) permitted the solubilization of PCL in water.The reported work illustrated the importance of macromolecular chemistry for the obtaining of amphiphilic copolymers with controlled molecular weight and narrow molar mass distributions which self-assemble in water. Such kind of materials could be used in the biomedical field.

Les polyesters aliphatiques dégradables tels que la poly(e-caprolactone) (PCL), le poly(glycolide) (PGA) ou le poly(lactide) (PLA) présentent de nombreuses applications dans le domaine biomédical. Lors de leur utilisation comme implant, le contrôle des propriétés de surface des polyesters est d'un intérêt considérable. En effet, les interactions avec le milieu vivant ont lieu aux interfaces. Ce travail de thèse vise donc le développement d'une méthode simple et généralisable de couplage de petites molécules, macromolécules et biomolécules sur des surfaces de PLA, en évitant sa dégradation. Cette méthode est basée sur une stratégie en deux étapes, initialement développée en solution sur la PCL et comprenant une activation anionique dans des conditions spécifiques, suivie de la fonctionnalisation par un groupe propargyle afin d'obtenir une surface de PLA « clickable ». Cette méthodologie a ensuite été utilisée pour synthétiser des surfaces de PLA (bio)actives anti-bactériennes et visibles en IRM. Les stratégies ont été initialement développées et optimisées en milieu homogène avec la PCL. Ensuite, les surfaces de PLA ont été modifiées, en milieu hétérogène, par CUAAC de poly(ammonium quaternaire)s fonctionnalisés azoture et d'un complexe de gadolinium fonctionnalisé azoture. / Biodegradable aliphatic polyesters such as poly(e-caprolactone) (PCL), poly(glycolide) (PGA) or poly(lactide) (PLA) are widely used in biomedical applications. When employed as an implantable material, the control of the surface properties of polyesters is of great interest because biochemical reactions occur on the surface or at interfaces. This work proposes a simple and versatile method to immobilize simple molecules, macromolecules, and biomolecules on PLA surfaces while preventing polymer degradation. The method is based on a one-pot, two-step procedure, first developed in solution with PCL and comprises an anionic activation under selected conditions followed by propargylation to form a ¡°clickable¡± PLA surface. This methodology is then employed to generate bioactive surfaces, namely antibacterial PLA surfaces and MRI-visible PLA surfaces. In a first place, chemical strategies are developed and optimized in homogeneous systems using PCL. Subsequently, PLA surfaces are modified, under heterogeneous conditions, by grafting of well-defined ¦Á-azido-functionalized poly(quaternary ammonium)s and an ¦Á-azido-functionalized complex of gadolinium to the propargylated PLA surface using "click" chemistry.

O poli(ε-caprolactona) (PCL) é um polímero biocompatível e biodegradável, aprovado pelo Food and Drug Administration (FDA) para ser usado como biomaterial. Diversos estudos utilizando sua forma linear ou ramificada têm demonstrado resultados promissores para seu uso no desenvolvimento de dispositivos médicos e em aplicações na área farmacêutica. O objetivo deste trabalho foi utilizar o PCL com estrutura estrelada (PCLE) para obter microesferas biorreabsorvíveis. Primeiramente realizou-se a avaliação das propriedades físico-químicas do PCLE por meio da cromatografia de permeação em gel (GPC), ressonância magnética de prótons (1H-RMN) e carbono (13C-RMN), calorimetria exploratória diferencial (DSC) e espectrometria por infravermelho com transformada de Fourier (FT-IR). A avaliação toxicológica do PCLE foi obtida por meio do ensaio de citotoxicidade utilizando células CHO-K1 e o corante vital 5-(3-carboximethoxifenil)-2-(4,5-dimetiltiazolil)-3-(4-sulfofenil) tetrazolium e do acoplador de elétrons fenazine metilssulfato (MTS/PMS). O ensaio de biodegradação foi conduzido em pH 7,4 na presença de lipase a 37 ºC. Após essas análises o PCLE foi utilizado para preparação de esferas por meio de emulsão complexa A/O/A. O PCLE foi caracterizado como um polímero de baixa massa molar, com dispersão de tamanho unimodal e cerca de 68,8 % de suas moléculas apresentaram estrutura estrelada com três braços. Em relação às propriedades térmicas o PCLE apresentou temperatura de fusão de 57,3 ºC e temperatura de transição vítrea de -54,3 ºC. A avaliação da citotoxicidade mostrou que o extrato de PCLE é compatível com o metabolismo celular. As microesferas obtidas a partir do PCLE, por emulsão A/O/A apresentaram polidispersão de tamanho. / The poly(ε-caprolactone) (PCL) is a biocompatible and biodegradable polymer which has been approved by Food and Drug Administration (FDA). Many studies that are using its linear or branched form have showed promising results for medical devices and controlled drug delivery applications. The aim of this research was the use of star-shaped PCL (PCLE) to prepare bioreabsorbable microspheres. At first, the physical-chemical properties were characterized by Gel Permeation Chromatography (GPC), Protons Resonance Magnetic Nuclear (1H-RMN), Carbon Resonance Magnetic Nuclear (13C-RMN), Differential Scanning Calorimetry (DSC) and Fourier Transformed Infrared Spectroscopy (FT-IR). The toxicological property was investigated by colorimetric assay using CHO-K1 cells and the vital dye (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) (MTS) and the electron acceptor phenazine methosulfate (PMS). The biodegradation behavior was evaluated in the presence of lipase at 37 ºC and pH 7.4. The microspheres were prepared by complex emulsion W/O/W. The PCLE was characterized as low molecular weight polymer with monomodal distribution and about 68,8 % of the molecules were three-arm branched. The melting and glass transition temperatures were 57.3 ºC and -54.3 ºC, respectively. The cytotoxicity evaluation showed that PCLE extract was cell compatible. The obtained microspheres showed diameter polydispersity.

O poli(ε-caprolactona) (PCL) é um polímero biocompatível e biodegradável, aprovado pelo Food and Drug Administration (FDA) para ser usado como biomaterial. Diversos estudos utilizando sua forma linear ou ramificada têm demonstrado resultados promissores para seu uso no desenvolvimento de dispositivos médicos e em aplicações na área farmacêutica. O objetivo deste trabalho foi utilizar o PCL com estrutura estrelada (PCLE) para obter microesferas biorreabsorvíveis. Primeiramente realizou-se a avaliação das propriedades físico-químicas do PCLE por meio da cromatografia de permeação em gel (GPC), ressonância magnética de prótons (1H-RMN) e carbono (13C-RMN), calorimetria exploratória diferencial (DSC) e espectrometria por infravermelho com transformada de Fourier (FT-IR). A avaliação toxicológica do PCLE foi obtida por meio do ensaio de citotoxicidade utilizando células CHO-K1 e o corante vital 5-(3-carboximethoxifenil)-2-(4,5-dimetiltiazolil)-3-(4-sulfofenil) tetrazolium e do acoplador de elétrons fenazine metilssulfato (MTS/PMS). O ensaio de biodegradação foi conduzido em pH 7,4 na presença de lipase a 37 ºC. Após essas análises o PCLE foi utilizado para preparação de esferas por meio de emulsão complexa A/O/A. O PCLE foi caracterizado como um polímero de baixa massa molar, com dispersão de tamanho unimodal e cerca de 68,8 % de suas moléculas apresentaram estrutura estrelada com três braços. Em relação às propriedades térmicas o PCLE apresentou temperatura de fusão de 57,3 ºC e temperatura de transição vítrea de -54,3 ºC. A avaliação da citotoxicidade mostrou que o extrato de PCLE é compatível com o metabolismo celular. As microesferas obtidas a partir do PCLE, por emulsão A/O/A apresentaram polidispersão de tamanho. / The poly(ε-caprolactone) (PCL) is a biocompatible and biodegradable polymer which has been approved by Food and Drug Administration (FDA). Many studies that are using its linear or branched form have showed promising results for medical devices and controlled drug delivery applications. The aim of this research was the use of star-shaped PCL (PCLE) to prepare bioreabsorbable microspheres. At first, the physical-chemical properties were characterized by Gel Permeation Chromatography (GPC), Protons Resonance Magnetic Nuclear (1H-RMN), Carbon Resonance Magnetic Nuclear (13C-RMN), Differential Scanning Calorimetry (DSC) and Fourier Transformed Infrared Spectroscopy (FT-IR). The toxicological property was investigated by colorimetric assay using CHO-K1 cells and the vital dye (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) (MTS) and the electron acceptor phenazine methosulfate (PMS). The biodegradation behavior was evaluated in the presence of lipase at 37 ºC and pH 7.4. The microspheres were prepared by complex emulsion W/O/W. The PCLE was characterized as low molecular weight polymer with monomodal distribution and about 68,8 % of the molecules were three-arm branched. The melting and glass transition temperatures were 57.3 ºC and -54.3 ºC, respectively. The cytotoxicity evaluation showed that PCLE extract was cell compatible. The obtained microspheres showed diameter polydispersity.

L'ostéoporose est la maladie métabolique la plus fréquente qui touche l'os. Plusieurs substances actives sont utilisées pour le traitement pharmacologique de cette maladie. Cependant, ce sont les bisphosphonates et surtout l'alendronate de sodium, qui sont prescrits en première intention. L'alendronate de sodium est, en effet, très efficace mais présente une faible absorption quand il est administré par la voie orale. Sa solubilité dans l'eau est de 20 mg/ml. Il présente en outre une faible biodisponibilité (de 0,6 à 0,7%). Cette substance active est aussi à l'origine d'effets indésirables d'irritation au niveau de l'oesophage, l'estomac et l'intestin. Ces effets sont dus à un contact local des cristaux de la substance active avec la muqueuse. L'approche d'encapsulation des substances actives dans des particules polymériques a permis d'obtenir plusieurs bénéfices thérapeutiques comme l'amélioration de la biodisponibilité et la diminution des effets indésirables. Dans la première partie de notre étude, on a réalisé l'encapsulation de l'alendronate dans des nanoparticules à base de poly-epsilon-caprolactone en utilisant la nanoprécipitation et l'émulsion double. Les nanoparticules obtenues ont une forme sphérique et une taille comprise entre 200 et 450 nm. Le meilleur pourcentage d'encapsulation a été de 34% et il a été obtenu avec la technique d'émulsion double. Ceci confirme que cette méthode est plus adaptée à l'encapsulation des molécules hydrophiles. Le profil de libération in vitro a montré deux phases : une première phase de libération relativement rapide et une deuxième phase beaucoup plus lente. L'analyse par modélisation mathématique a montré que la libération in vitro de l'alendronate se fait par diffusion et relâchement des chaines polymériques / Osteoporosis is the most frequent metabolic disease that affects bone. Many actives have been used as pharmacological treatment of this disease. However, bisphosphonates, especially, alendronate sodium, are indicated as first line regimen. Alendronate is highly efficient but presents low absorption after oral administration. Its solubility in water is 20 mg/ml. It has also poor bioavailability (0.6-0.7%). In addition, this active could lead to many side effects, which are mainly related to the esophagus, the stomach and the intestine. Such effects are linked to a local contact of drug crystals with the mucosa. Encapsulation of active molecules allowed the obtaining of many advantages over conventional pharmaceutical forms such as, bioavailability and tolerance enhancement. In the first part of our study, we managed to encapsulate alendronate sodium in poly-epsilon-caprolactone nanoparticles via two techniques: nanoprecipitation and double emulsion. Obtained nanoparticles presented a spherical form. Their size ranged between 200 and 450 nm. The highest encapsulation efficiency value was 34% and was obtained via double emulsion technique. This confirms that double emulsion is more suitable for hydrophilic drugs encapsulation. In vitro release profile showed two phases: first phase of burst release and a second more prolonged phase. Mathematical modeling showed that alendronate in vitro release occurs by drug diffusion and polymer chain relaxation. In the second experimental part, we managed to find a more interesting alternative. In fact, we opted for the use of chitosan which is a natural hydrophilic polymer. One of the obtained advantages is the avoidance of organic solvents use. In addition, this approach allowed the enhancement of encapsulation efficiency as this value increased to 70%. The used technique is ionic gelation. It is a simple encapsulation technique that is based on the transformation of a dissolved polymer to a gel-like state

Ce travail a pour objectif principal la modification de la surface de nanoparticules de polymères par de nouveaux copolymères amphiphiles et biocompatibles, possédant différentes architectures. Les copolymères considérés dans cette étude sont composés d'une chaine hydrophile de poly(oxyde d'éthylène) (POE) et d'une chaîne hydrophobe à base de poly(ε-caprolactone) (PCL).<br />A partir d'un POE coiffé par une unité ε-caprolactone et par un groupement méthoxy à ses extrémités α et ω, respectivement, (γPOE.CL), des copolymères amphiphiles greffés, PCL-g-POE, et un copolymère ternaire possédant une architecture en étoile ont été synthétisés. Des copolymères diblocs, POE-b-PCL, ont également été préparés. <br />Les copolymères diblocs et greffés de POE et PCL, tensioactifs, ont été utilisés pour stabiliser et modifier la surface de nanoparticles polymères (NP), vecteurs potentiels pour la délivrance de principes actifs. L'effet des propriétés des copolymères (architecture, composition et quantité) sur la formation et la structure des nanoparticules, a été examiné. De plus, l'activation du complément, c.-à.-d. la furtivité des nanoparticules, en fonction de la composition et de l'architecture du copolymère utilisé a été étudiée.<br />Un autre défi relevé dans ce travail est la fonctionnalisation de la surface de nanoparticules pas des motifs mannose afin de cibler des cellules dendritiques. A cet effet, des dérivés du mannose ont été fixés de manière covalente à l'extrémité de la poly(ε-caprolactone) et de copolymères diblocs POE-b-PCL. Ces derniers ont été utilisés avec succès pour modifier la surface de nanoparticules de polylactide.

L'objectif de ce travail de thèse était la synthèse d'un nouveau matériau polyuréthane biorsourcé composé par du caoutchouc naturel modifié chimiquement et par du poly(ε-caprolactone), (PCL), en présence ou absence d'isocyanates. Des oligoisoprènes téléchéliques hydroxylés (HTNR) ont été obtenus après époxidation du caoutchouc naturel et réduction des oligomères carbonyles. Plusieurs paramètres ont été étudiés comme la nature et la quantité relative de diisocyanate, le rapport molaire entre diisocyanate et diol (NCO:OH), l'influence de la masse molaire des diols HTNR et PCL, le pourcentage de 1,4-butane diol (BDO, extenseur de chaîne), et le rapport molaire entre les diols HTNR:PCL. Trois types de diisocyanate ont été employés : isophorone diisocyanate (IPDI), toluène-2,4-diisocyanate (TDI) et hexaméthylène diisocyanate (HDI). Masses molaires différentes ont été utilisées pour les diols HTNR et PCL: 1700, 2800 et 2900 g/mol pour HTNR et 530 et 2000 g/mol pour PCL. Le rapport molaire entre NCO:OH était entre 0,75:1,00 - 2,85:1,00. Les PU ont été préparés par la méthode " one shot " et les structures chimiques des HTNR et PU ont été identifiées par 1H-NMR et FTIR. La résistance à la traction et à la rupture ont été étudiées. La caractérisation a été conduite par DSC, DMTA, ATG et spectroscopie Raman. Une étude préliminaire a montré que la masse molaire du PU augmentait avec le rapport NCO:OH et le temps de réaction, et que le chloroforme n'était pas un bon solvant pour obtenir des films. Le tetrahydrofurane était le solvant le plus approprié et il a été utilisé par la suite pour toutes les polymérisations. Le rapport NCO:OH = 1,25:1,00 s'est révélé optimal pour obtenir des films. L'analyse FTIR a permis de vérifier la présence de liaisons uréthane, de points de réticulation et de branchements. Le polyuréthane a montré des propriétés mécaniques excellentes dépendantes de la composition chimique. Si on exclue l'utilisation de PCL2000 et de HDI, le comportement à la traction était caractéristique des élastomères. Les PU étaient amorphes sauf lorsque le HDI a été employé. Duos ce cos été obtenais un PU semi cristallin. Cette cristallinité augmente le module de Young, la résistance à la rupture, la dureté et la stabilité thermique du PU. Pour ce PU ont observé une séparation de phase entre les segments du PCL et du HTNR. Les chaînes plus longues et plus flexibles du HTNR et leur non polarité sont responsables de la diminution des propriétés mécaniques et des températures de transition. Le materiae pane d'un comportement élastomère a un comportement plastique pour un rapport NCO:OH élevé (2,85 :1,00). Le dégréé de réticulation élevé a été retenu comme la cause pour laquelle il n'y avait pas de séparation de phase entre les segments souples et durs. La liaison hydrogène entre le diol PCL et le segment hard a généré des Tg élevées. Les spectres Raman ont montré la formation de la liaison uréthane du PU contenant différents diisocyanates. La synthèse de PU sans diisocyanate a été obtenue grâce à une réaction de polyaddition entre des carbonates cycliques téléchéliques dérivés du PCL et du caoutchouc naturel, et la 1,4-butylène diamine. Les structures contenant des carbonates cycliques ont été obtenues grâce à la modification des groupes OH sur le HTNR et le PCL à groupes carboxyle, utilisant l'anhydride succinique, et a la réaction successive avec le glycérol carbonate.

Orientador: Marcos Akira D' Ávila / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-24T19:12:36Z (GMT). No. of bitstreams: 1 Almeida_RosemeiredosSantos_D.pdf: 3414008 bytes, checksum: 9f5516445d3c90d0f22d3a953197d6b7 (MD5) Previous issue date: 2014 / Resumo: O polímero Poli(caprolactona) (PCL) tem sido amplamente usado como biomaterial nas últimas décadas. Sua biocompatibilidade e boas propriedades termo-mecânicas são as principais características que levam à seleção desse material para aplicação nas áreas biotecnológica, farmacêutica e têxtil. Neste trabalho, montou-se um equipamento para realizar o processamento de eletrofiação e caracterização de mantas formadas por fibras de PCL puro e nanocompósitos de PCL/nanotubos de carbono (NTC). Recorreu-se à eletrofiação com a aplicação de um campo elétrico gerado por uma corrente alternada (CA) e por uma corrente contínua (CC) simultaneamente (CA/CC) visando o controle da estabilidade do escoamento do jato polimérico durante o processamento a fim de determinar os parâmetros de processo e comparar os efeitos das diferentes frequências durante o processamento. Foram obtidos também nanocompósitos de PCL/óxido de grafeno (GO) com aplicação de um potencial elétrico em corrente contínua (CC), a fim de determinar os parâmetros de processos em diferentes concentrações de óxido de grafeno. As soluções/suspensões utilizadas no processo foram caracterizadas através de medições de condutividade elétrica, tensão superficial e propriedades reológicas. As fibras obtidas na forma de mantas porosas não-tecidas (non woven) foram caracterizadas por Microscopia Eletrônica de Varredura (MEV), Espectroscopia de Infravermelho com Transformada de Fourier (FT-IR), Calorimetria Exploratória Diferencial (DSC), Análise Termogravimétrica (TGA), Resistividade, Ângulo de contato ensaios mecânicos de tração e ensaios biológicos in vitro com células tronco mesenquimais humanas (hMSCs). Observou-se que o diâmetro médio das fibras depende da frequência CA aplicada durante a eletrofiação. A análise por FT-IR mostrou que houve a interação entre o PCL e o NTC, e as análises biológicas indicaram que as mantas PCL/GO são promissoras para uso como biomaterial / Abstract: Poly (??caprolactone) (PCL) has been widely used as biomaterial in the last decades. Its biocompatibility and good thermomechanical properties are the main features that lead to the selection of this material for applications in biotechnological, pharmaceutical and textile areas. In this work, an equipment was set up to perform electrospinning; characterization of fibrous mats formed by pure PCL fibers and nanocomposites of PCL/carbon nanotubes (CNT). Electrospinning based on the application of an electric field generated by an alternating current (AC) and a direct current (DC) simultaneously (AC/DC) was performed aiming to control the stability of the jet flow of the polymer during processing in order to determine the process parameters and compare the effects of different frequencies during processing. Nanocomposites of PCL/graphene oxide (GO) with application of a DC electrical potential were also obtained in order to determine the process parameters at different concentrations of graphene oxide. Solutions/suspensions employed in the process were characterized by measurements of electrical conductivity, surface tension and rheological properties. The fibers obtained in the form of non- woven porous mats were characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FT-IR), Differential canning Calorimetry (DSC), Thermogravimetric Analysis (TGA), resistivity, contact angle and mechanical properties was measured, and in vitro biological assays with human mesenchymal stem cells (hMSCs) was evaluated. It was observed that the average diameter of the fibers depends on the AC frequency applied during electrospinning. The FT-IR analysis showed that there was interaction between the PCL and the CNTs, and biological analysis indicated that the blankets of PCL/CNT and PCL/GO are promising for use as a biomaterial / Doutorado / Materiais e Processos de Fabricação / Doutora em Engenharia Mecânica