Study of morphology and phase diagram of the H-shaped (AC)B(CA) ternary block copolymers using self-consistent field theory

By using a combinatorial screening method based on the self-consistent field theory (SCFT) for polymer systems, the micro-phase morphologies of the H-shaped (AC)B(CA) ternary block copolymer system are studied in three-dimensional (3D) space. By systematically varying the volume fractions of the components A, B, and C, six triangle phase diagrams of this H-shaped (AC)B(CA) ternary block copolymer system with equal interaction energies among the three components are constructed from the weaker segregation regime to the strong segregation regime, In this study, thirteen 3D micro-phase morphologies for this H-shaped ternary block copolymer system are identified to be stable and seven 3D microphase morphologies are found to be metastable.

Synthesis and crystallization behaviors of poly(styrene-b-isoprene-b-epsilon-caprolactone) triblock copolymers

The triblock copolymers, poly(styrene-b-isoprene-b-epsilon-caprolactone)s (PS-b-PI-b-PCL) have been synthesized successfully by combination of anionic polymerization and ring-opening polymerization. Diblock copolymer capped with hydroxyl group, PS-b-PI-OH was synthesized by sequential- anionic polymerization of styrene and isoprene and following end-capping reaction of EO, and then it was used as macro initiator in the ring-opening polymerization of CL. The results of DSC and WAXD show big effect of amorphous PS-b-PI on the thermal behaviors of PCL block in the triblock copolymers and the lower degree of crystalline in the triblock copolymer with higher molecular weight of PS-b-PI was observed. The real-time observation on the polarized optical microscopy shows the spherulite growth rates of PCL27, PCL328 and PS-b-PI-b-PCL344 are 0.71, 0.46 and 0.07 mu m s(-1), respectively. The atomic force microscopy (AFM) images of the PS90-b-PI66-b-PCL-(28) show the columns morphology formed by it's self-assembling.

Synthesis and characterization of ABC ternary segregated H-shaped copolymers

The synthesis of a novel ABC ternary segregated H-shaped copolymer is described, of which a central poly(ethylene glycol) (PEG) chain is terminated on both sides by polystyrene (PS) and poly(tert-butylacrylate) (PtBA) chains. The synthetic procedure involves functionalization of PEG by 2-bromosuccinic anhydride followed by esterification of 1,6-hexanediol, which gives its ends the bifunctional nature that allows sequential growth of two PS, then two PtBA arms via atom transfer radical polymerization (ATRP). The resulting segregated H-shaped copolymers were characterization by NMR spectroscopy and gel permeation chromatography (GPC). All these copolymers were affirmed to have well-defined structures and narrow molecular weight distributions.

Compatibilizing effect of polystyrene-block-poly(4-vinylpyridine) for poly(2,6-dimethyl-1,4-phenyleneoxide) chlorinated polyethylene blends

The compatibilizing effect and mechanism of compatibilization of the diblock copolymer polystyrene-block-poly(4-vinylpyridine) P(S-b-4VPy) on immiscible blends of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO)/chlorinated polyethylene (CPE) were studied by means of scanning electron microscopy (SEM), differential scanning calorimetry (DSC), mechanical properties and FTIR measurements. The block copolymer was synthesized by sequential anionic polymerization and melt-blended with PPO and CPE. The results show that the P(S-b-4VPy) added acts as an effective compatibilizer, located at the interface between the PPO and the CPE phase, reducing the interfacial tension, and improving the interfacial adhesion. The tensile strength and modulus of all blends increase with P(S-b-4VPy) content, whereas the elongation at break increases for PPO-rich blends, but decreases for CPE-rich blends. The polystyrene block of the diblock copolymer is compatible with PPO, and the poly(4-vinylpyridine) block and CPE are partially miscible.

Modification d'acides biliaires à l'aide de polymères pour en moduler les propriétés d'agrégation

Les polymères amphiphiles sont largement utilisés pour les applications biomédicales et pharmaceutiques. Afin d’améliorer les chances de biocompatibilité des nouveaux polymères que nous voulons développer, nous avons utilisé des composés naturels, les acides biliaires, comme produits de départ dans la synthèse de ces polymères. De nouveaux polymères anioniques amphiphiles dérivés de l’acide cholique ont été préparés par polymérisation radicalaire par transfert d’atomes. Par un contrôle rigoureux des conditions de polymérisation, des bras de poly(acide acrylique) de différentes longueurs ont été greffés sur le squelette de l’acide cholique. L’architecture moléculaire des polymères a été étudiée par spectroscopie 1H RMN et par spectrométrie de masse. Ces polymères en étoile formés par l’acide biliaire modifié sont capables de s’agréger dans l’eau même si les groupements hydroxyles ont été remplacés par des segments plus volumineux. Il a été observé que les liaisons ester entre le polymère et le cœur d’acide cholique sont sensibles à l’hydrolyse en solution aqueuse. Pour remédier au problème de stabilité en solution aqueuse et pour avoir, en même temps, des bras hydrophiles non ioniques et biocompatibles, de l’oxyde d’éthylène a été polymérisé sur l’acide cholique par polymérisation anionique. Les liaisons éther formées entre le polymère et les groupements hydroxyles de l’acide biliaire sont plus stables que les liaisons ester sur le polymère de poly(acide acrylique). Les conditions de réaction de la polymérisation anionique ont été optimisées et ont donné des polymères aux architectures et aux masses molaires contrôlées. Les nouveaux polymères forment des agrégats sphériques tel qu’observé par microscopie électronique à transmission avec des échantillons préparés par la méthode de fracture à froid. Leur morphologie est différente de celle des agrégats cylindriques formés par les acides biliaires. Avec la méthode optimisée pour la polymérisation anionique, l’éther d’allyle et glycidyle a été polymérisé sur un dérivé d’acide cholique, suivi par une thiolation des liaisons doubles pour introduire l’amine ou l’acide sur la chaîne polymère. Cette addition radicalaire est efficace à plus de 90%. Les polymères qui en résultent sont solubles dans l’eau et s’agrègent à une certaine concentration critique. Il est particulièrement intéressant d’observer la thermosensibilité des polymères ayant des groupements amine, laquelle peut être modulée en acétylant partiellement les amines, donnant des points nuages entre 15 et 48°C.

Développement de tensioactifs à base d’acides biliaires pegylés pour des applications pharmaceutiques

Les acides biliaires sont reconnus comme des tensioactifs d’origine biologique potentiellement applicables dans le domaine pharmaceutique. Leurs structures en font une plateforme idéale pour l’obtention de nouvelles architectures polymères. Des composés synthétisés par polymérisation anionique de dérivés d’oxirane comme l’oxyde d’éthylène, offre des dérivés amphiphiles pegylés démontrant des propriétés d’agrégation intéressantes en vue d’une amélioration de la biocompatibilité et de la capacité d’encapsulation médicamenteuse. Une large gamme d’acides biliaires pegylés (BA(EGn)x) a été préparée avec comme objectif premier leurs applications dans la formulation de principes actifs problématiques. Pour cela, une caractérisation rigoureuse du comportement de ces dérivés (modulation de la longueur (2 < n < 19) et du nombre de bras (2 < x < 4) de PEG) en solution a été réalisée. Dans le but d’améliorer la biodisponibilité de principes actifs lipophiles (cas de l’itraconazole), des nanoémulsions spontanées, composées de BA(EGn)x et d’acide oléique, ont été développées. L’évaluation in vitro, de la toxicité (cellulaire), et de la capacité de solubilisation des systèmes BA(EGn)x, ainsi que les paramètres pharmacocinétiques in vivo (chez le rat), suggèrent une livraison contrôlée par nos systèmes auto-assemblés lors de l’administration orale et intraveineuse. Aussi, la synthèse de copolymères en blocs en étoile à base d’acide cholique pegylés a été effectuée par polymérisation anionique par addition d’un second bloc au caractère hydrophobe de poly(éther d’allyle et de glycidyle) (CA(EGn-b-AGEm)4). Selon le ratio de blocs hydrophiles-hydrophobes CA(EGn-b-AGEm)4, des réponses thermiques en solution (LCST) ont été observées par un point de trouble (Cp) entre 8 oC et 37 oC. Un mécanisme de formation d’agrégats en plusieurs étapes est suggéré. La thiolation des allyles des PAGE permet une fonctionnalisation terminale à haute densité, comparable aux dendrimères. Les caractérisations physico-chimiques des CA(EGn-b-AGEm-NH2)4 et CA(EGn-b-AGEm-COOH)4 indiquent la formation de structures auto-assemblées en solution, sensibles à la température ou au pH. Cette fonctionnalisation élargie le domaine d’application des dérivés d’acides biliaires pegylés en étoile vers la transfection d’ADN, la livraison de siRNA thérapeutiques ou encore à une sélectivité de livraison médicamenteux (ex. sensibilité au pH, greffage ligands).

Noves aproximacions a la síntesi i caracterització de poliglicols al·lílics, polihidrosiloxans i surfactants copolimèrics. Avaluació d'aquests surfactants en formulacions de poliuretà

Els polímers són una sèrie de compostos que troben un ampli ventall d'aplicacions en la indústria actual. Un exemple són les espumes de poliuretà, estructures de tipus cel·lular obtingudes mitjançant la reacció química entre compostos de tipus isocianat i compostos de tipus poliol (polièters amb diferent nombre de grups hidroxil). És imprescindible l'ús d'additius d'estructura tensioactiva (surfactants de silicona) per estabilitzar el procés d'espumació i per proporcionar una estructura cel·lular ordenada i homogènia en mida i distribució. La síntesis i caracterització de les molècules precursores (polihidrosiloxans i polièters al·lílics), l'estudi de la reacció d'hidrosililació com a via d'obtenció dels diferents surfactants per reacció d'addició entre els polihidrosiloxans i els polièters al·lílics i la caracterització i avaluació en formulacions comercials de poliuretà dels surfactants sintetitzats han constituït els objectius del present treball. MEMÒRIA La Tesi Doctoral ha estat presentada seguint el següent esquema: CAPÍTOL I. INTRODUCCIÓ A LA QUÍMICA DEL POLIURETÀ. Es presenten els principis de la química del poliuretà, fent esment dels recents avenços en la síntesis i caracterització d'aquests compostos polimèrics, així com un apartat concret centrat en els surfactants de silicona. Es presenten les estructures habituals d'aquests compostos comercials i es detallen les reaccions de síntesi i les característiques físiques que aquests compostos proporcionen a les espumes de poliuretà. CAPÍTOL II. OBJECTIUS. 1.- Síntesis y caracterització d'una àmplia gamma de poliglicols al·lílics i de polihidrosiloxans amb grups hidrur reactius, ambdós precursors d'estructures polimèriques de tipus surfactant. 2.- Estudi de la reacció d'hidrosililació com a via de formació d'enllaços Si-C no hidrolitzables, mitjançant la reacció d'addició entre els substrats al·lílics insaturats i els polisiloxans amb grups hidrur reactius. 3.- Caracterització de les estructures polimèriques de tipus surfactant sintetitzades i avaluació d'aquestes en formulacions de poliuretà, a fi de relacionar l'estructura química d'aquests oligómers amb els efectes físics que originen en l'espuma de poliuretà. CAPÍTOL III. SÍNTESI I CARACTERITZACIÓ DE SUBSTRATS AL·LÍLICS INSATURATS DE TIPUS POLIGLICOL. S'han caracteritzat per HPLC-UV una sèrie de polietilenglicols comercials. S'ha estudiat la reacció de derivatització al·lílica sobre els grups hidroxil dels polièters comercials (PEG, PPG i copolímers PEG-PPG) i s'han caracteritzat exhaustivament els productes sintetitzats (1H,13C-RMN, GC, GC-MS, FTIR, ESI-MS, HPLC-UV). S'ha iniciat un estudi de polimerització aniònica sobre nous epòxids amb un punt de diversitat molecular, sintetitzant-se i caracteritzant-se els corresponents nous polièters obtinguts. CAPÍTOL IV. SÍNTESI I CARACTERITZACIÓ DE POLIHIDROSILOXANS REACTIUS. S'estudia la síntesis de polihidrosiloxans amb grups hidrur reactius, mitjançant la reacció de polimerització aniònica d'obertura d'anell ("AROP, anionic ring opening polimerization") i mitjançant la reacció de polimerització per equilibració catiònica. Es presenta una caracterització exhaustiva dels productes sintetitzats i es descriu la naturalesa de la microestructura polimèrica a partir de la distribució bivariant dels copolímers PDMS-co-PHMS (poli(dimetilsiloxà)-co-poli(hidrometilsiloxà)). CAPÍTOL V. ESTUDI SISTEMÀTIC DE LA REACCIÓ D'HIDROSILILACIÓ. S'ha estudiat la reacció d'hidrosililació amb la finalitat de sintetitzar estructures copolimèriques poliglicol-polisiloxà a partir de la reacció de polisiloxans hidrur reactius i polièters al·lílics. S'han provat diferents catalitzadors (Pt/C 5%, cat. de Speier i cat. de Karstedt), s'han sintetitzat diferents estructures tensoactives (lineals i ramificades) i s'ha modelitzat les diferents reaccions secundàries observades, per presentar un estudi mecanístic de la reacció d'hidrosililació aplicada a la síntesis de molècules d'elevat PM a partir de la reacció entre substrats al·lílics insaturats i polihidrosiloxans. CAPÍTOL VI. AVALUACIÓ DELS SURFACTANTS EN FORMULACIONS DE POLIURETÀ. S'ha estudiat la idoneïtat dels surfactants de silicona sintetitzats en diferents formulacions de poliuretà comercials. S'ha relacionat el comportament físic d'aquests surfactants en les espumes de poliuretà amb la seva estructura química a partir de l'anàlisi per microscòpia electrònica de rastreig. CAPÍTOL VII. CONCLUSIONS. S'han esposat les conclusions extretes de cada capítol.

Fractionated crystallization and fractionated melting of confined PEO microdomains in PB-b-PEO and PE-b-PEO diblock copolymers

The confined crystallization of poly(ethylene oxide) (PEO) in predominantly spherical microdomains formed by several diblock copolymers was studied and compared. Two polybutadiene-b-poly(ethylene oxide) diblock copolymers were prepared by sequential anionic polymerization (with approximately 90 and 80 wt % polybutadiene (PB)). These were compared to equivalent samples after catalytic hydrogenation that produced double crystalline polyethylene-b-poly(ethylene oxide) diblock copolymers. Both systems are segregated into microdomains as indicated by small-angle X-ray scattering (SAXS) experiments performed in the melt and at lower temperatures. However, the PB-b-PEO systems exhibited a higher degree of order in the melt. A predominantly spherical morphology of PEO in a PB or a PE matrix was observed by both SAXS and transmission electron microscopy, although a possibly mixed morphology (spheres and cylinders) was formed when the PEO composition was close to the cylinder-sphere domain transitional composition as indicated by SAXS. Differential scanning calorimetry experiments showed that a fractionated crystallization process for the PEO occurred in all samples, indicating that the PE cannot nucleate PEO in these diblock copolymers. A novel result was the observation of a subsequent fractionated melting that reflected the crystallization process. Sequential isothermal crystallization experiments allowed us to thermally separate at least three different crystallization and melting peaks for the PEO microdomains. The lowest melting point fraction was the most important in terms of quantity and corresponded to the crystallization of isolated PEO spheres (or cylinders) that were either superficially or homogeneously nucleated. This was confirmed by Avrami index values of approximately 1. The isothermal crystallization results indicate that the PE matrix restricts the crystallization of the covalently bonded PEO to a higher degree compared to PB.

Nanopartikel durch Strukturfixierung mizellarer Assoziate aus amphiphilen, endgruppenfunktionalisierten Diblockcopolymeren

Nanopartikel durch Strukturfixierung mizellarer Assoziate aus amphiphilen, endgruppenfunktionalisierten Diblockcopolymeren Zwei unterschiedliche Diblockcopolymersysteme mit Molmassen unterhalb von Mw = 10 000 g/mol wurden über anionische Polymerisation synthetisiert. Ein hetero-telecheles a,w-Poly(dimethylsiloxan)-b-Poly(ethylenoxid) (PDMS-PEO) Diblockcopolymer wurde mit einer Methacrylatendgruppe am PDMS und entweder einer Benzyl-, Hydroxy- oder Carboxylatendgruppe am PEO funktionalisiert. Ein Poly(butadien)-b-Poly(ethylenoxid) (PB-PEO) Diblockcopolymer wurde am PEO ebenfalls entweder mit einer Benzyl-, Hydroxy- oder Carboxylatendgruppe funktionalisiert. In selektiven Lösungsmitteln wie Wasser oder Methanol bilden beide Diblockcopolymersysteme supramolekulare Strukturen mit sphärischer, zylindrischer oder toroider Geometrie aus, die mit statischer und dynamischer Lichtstreuung in Lösung und mit Rasterkraftmikroskopie (AFM) und Transmissionselektronenmikroskopie (TEM) auf der Oberfläche untersucht wurden. Durch Zusatz eines Vernetzers und Initiators wurden die selbstassoziierenden Mizellen des PDMS-PEO Diblockcopolymers permanent durch radikalische Polymerisation mit UV-Licht fixiert. Mizellen des PB-PEO Diblockcopolymers wurden über Bestrahlung mit gamma-Strahlen permanent fixiert. Die Untersuchung der resultierenden Nanopartikel beider Diblockcopolymersysteme mit AFM und TEM zeigte, daß diese sogar in nicht selektiven Lösungsmitteln wie Tetrahydrofuran formstabil bleiben.

Neue Methoden zur Darstellung von Blockcopolymeren unter Beteiligung radikalischer Polymerisationsmechanismen

Im Rahmen dieser Dissertation wurden die Synthese und die Charakterisierung verschiedener, zum Teil neuartiger Blockcopolymere beschrieben, wobei die Einbeziehung radikalischer Polymeri-sationsmechanismen den konzeptionellen Kern ausmachte. Mit einer auf die jeweilige Kombination von Monomeren zugeschnittenen Syntheseroute gelang die Verknüpfung von Segmenten, die allein mittels der herkömmlich zur Synthese von Blockcopolymeren genutzten, ionischen Mechanismen nur mit hohem Aufwand oder gar nicht zu verbinden sind. Auf materieller Seite stand die Herstellung amphiphiler Strukturen im Vordergrund. Diese wurden entweder direkt beim Aufbau der Blockcopo-lymere oder nach anschließender polymeranaloger Umsetzung eines ihrer Segmente erhalten. Solche amphiphilen Substanzen besitzen aufgrund ihrer Grenzflächenaktivität Anwendungspotential z. B. als Stabilisatoren in der Dispersionspolymerisation oder als Flokkulantien. Es wurden drei Verfahren zum Aufbau von Blockcopolymeren untersucht:1. Die Transformation von anionischer zu freier radikalischer Polymerisation für die Synthese von Polystyrol-b-poly(N-vinylformamid) (PS-b-P(VFA)).2. Die Transformation von anionischer zu kontrollierter radikalischer Polymerisation (ATRP) für den Aufbau von Blockcopolymeren aus Poly(dimethylsiloxan) PDMS und Segmenten von t-Butylacrylat (t-BuA) bzw. (2-(Trimethylsiloxy)ethyl)methacrylat (TMS-HEMA).3. Die kontrollierte radikalische Polymerisation unter Einsatz von Triazolinyl als Gegenradikal zur Synthese von Poly[(2-(trimethylsiloxy)ethyl)methacrylat]-b-polystyrol (P(TMS-HEMA)-b-PS) als alternative Route zur anionischen Polymerisation.

Synthesis and characterization of polymers containing oligothiophenes

In the present work a series of thiophene oligomers of three and six thiophene units were synthesized, starting from thiophene, and characterized. Polymers containing these electroative side groups were then prepared by two strategies. The oligomers were attached to existing polymer systems and were connected to a polymerizable unit leading to monomer containing the oligothiophenes as side groups. Subsequently the properties of the monomers and the polymers were investigated. A butylcellulose derivative carrying terthienyl side chains (BCTTE, 26) was synthesized starting from cellulose acetate and 5-(2-chloroethyl)-2,2':5',2'-terthiophene (4). The polymer had a degree of substitution (DS) of the butyl and terthienyl side chains of DSbutyl = 1.9 and DSterth = 0.35, respectively. It was successfully spread on a Langmuir-Blodgett (LB) trough and then transferred to several solid substrates. X-rays reflectometry showed an ordered architecture of the cellulose backbones. However, the terthiophene side groups were found as isotropically aligned by polarized UV-Vis spectroscopy. When used as anode material in the electropolymerization of 3-pentylthiophene (28), polythiophene was grafted onto the cellulose backbone through the terthienyl side groups. The polythiophene chains showed an average anisotropic alignment of 20 % along the LB dipping direction, calculated by means of polarized UV-Vis spectroscopy. A second butylcellulose derivative carrying sexithienyl side chains (BCST) was synthesized and investigated, starting from butylcellulose and 2-[b ', b ''-dipentyl-5'''-(2-hydroxyethyl)-2,2': 5',2':5',2'':5'',2'':5'',2'''-sexithiophen-5-yl]-ethyl p-toluensulfonate (7). The polymer showed formation of stable LB monolayers at the air-water interface, but its transfer onto solid substrates was not successful. A poly(p-phenylene-ethynylene) bearing sexithienyl side chains (BzAcST, 31) was prepared by reaction of the two monomers 2-[b ', b ''-dipentyl-5'''-(2-hydroxyethyl)-2,2': 5',2':5',2'':5'',2'':5'',2'''-sexithiophen-5-yl]-ethyl 2,5-diiodobenzoate (15) and 2-[b', b ''-dipentyl-5'''-(2-hydroxyethyl)-2,2':5',2':5',2'':5'',2'':5'',2'''-sexithiophen-5-yl]-ethyl 2,5-diethynylbenzoate (18). The polymer was obtained as insoluble product. Upon oxidation with FeCl3 (doping) of the polymer suspension, BzAcST showed an electrical conductivity of ó = 2.5 . 10 -6 S/cm, a typical value for semiconductors. The IR spectrum of the doped polymer presented the diagnostic bands of oxidized sexithiophene in good agreement with literature results. Along with the monomer and polymer synthesis, an a,a '-disubstituted sexithiophene, b ', b ''-dipentyl-5,5'''-bis-(2-hydroxyethyl)-2,2':5',2':5',2'':5'',2'':5'',2'''-sexithiophene (6a),was synthesized and characterized. The UV-Vis absorption of the chromophore wasinvestigated as a function of temperature and different solvents, showing a blue-shift of the absorption maximum with increasing temperature and a red-shift changing the solvent from hexane to ethanol to toluene. Monitoring the change of the UV-Vis spectrum upon electrochemical oxidation, the oxidized chromophore showed a new broad absorption band, red shifted with respect to the p -p* transition of the neutral state. Upon reduction, the new band disappeared and the UV-Vis spectrum of the chromophore was restored. Such oxidation-reduction cycles were totally reversible. This feature, together with the absorption maximum falling in the visible region, makes this chromophore a suitable compound for the development of an electrochemical sensor.Attempts to polymerize acrylic monomers carrying sexythienyl side chains both via radical polymerization, as in the case of 2-[b ', b ''-dipentyl-5'''-(2-hydroxyethyl)-2,2': 5',2':5',2'':5'',2'':5'',2'''-sexithiophen-5-yl]-ethyl acrylate (8), and anionic polymerization, as in the case of 2-{b ', b ''-dipentyl-5'''-[2-(tertbutyldimethylsiloxy)ethyl]-2,2':5',2':5',2'':5'',2'': 5'',2''' -sexithiophen-5-yl}-ethylacrylate (29), were not successful, probably due to the steric hindrance of the oligothiophene side group. However, due to the time consuming and therefore restricted availability of the monomers, a screening of the polymerization conditions towards the formation of polymeric material was not possible.

Strukturbildung doppelthydrophiler Blockcopolymere mit mehrwertigen organischen Gegenionen

Sowohl die Komplexierung von Polyelektrolyten mit anorganischen Salzen, als auch die mit entgegengesetzt geladenen Polymeren wurde von vielen Autoren bereits intensiv untersucht. Doch gerade mit Molekülen die zwischen diesen beiden Extremen liegen, sollte es möglich sein, durch elektrostatische Wechselwirkungen gezielt nanometergroße Teilchen definierter Struktur herzustellen. Ziel dieser Arbeit war es deshalb, die Strukturbildung doppelthydrophiler Blockcopolymere mit mehrwertigen organischen Gegenionen zu untersuchen und insbesondere Parameter für die Bildung supramolekularer Strukturen in wässriger Lösung zu finden. Als Blockcopolymer wurde dabei Polyethylenoxid-b-methacrylsäure mittels anionischer Polymerisation hergestellt und mittels Gelpermeationschromatographie (GPC) und Kernresonanzspektroskopie (NMR)charakterisiert. Die Strukturbildung des Polyelektrolyten mit mehrwertigen organischen Gegenionen wurde in pH = 6- und pH = 7-Pufferlösung mit dynamischer und statischer Lichtstreuung, Kleinwinkelneutronenstreuung und Ultrazentrifugation untersucht. Mit Diaminobenzidin als Gegenion wurden dabei sphärische Komplexe mit einem hydrodynamischen Radius um 100 nm erhalten und mit Ultrazentrifugation der Anteil des Gegenions im Komplex quantifiziert. Die schlechte Löslichkeit des Diaminobenzidins in wässrigem Medium erschwerte allerdings die Interpretation der Ergebnisse. Trotzdem deuten diese darauf hin, dass keine Kolloidbildung des Diaminobenzidins, sondern eine Komplexierung der Einzelmoleküle mit dem Copolymer vorliegt. Um Probleme mit der Löslichkeit zu vermeiden, wurden schliesslich Polyamidoamin-Dendrimere als Gegenionen verwendet. Dabei wurde in pH = 6- und pH = 7-Pufferlösung für Dendrimere der Generation 4 mit steigender Gegenionenkonzentration ein kontinuierlicher Anstieg des hydrodynamischen Radius bis zu einer Größe von 70 nm gefunden. Mit Kleinwinkelneutronenstreuung konnte eine ellipsoidale Struktur dieser Komplexe beobachtet werden. Auch die Größe der Gegenionen spielt für die Bildung supramolekularer Aggregate eine Rolle. So zeigte sich, dass für Polyamidoamin-Dendrimere der Generation 2, analog zu denen der Generation 4, ein Anstieg des hydrodynamischen Radius mit steigender Gegenionenkonzentration zu beobachten ist. Für Generation 0-Dendrimere hingegen wurde ein umgekehrter Verlauf beobachtet, welcher dem für Diaminobenzidin gleicht. Somit kann man annehmen, dass die Aggregation mit kleinen Molekülen zu einer anderen Struktur der Komplexe führt, als die mit größeren Molekülen.

From amphiphilic block copolymers to ferrocenyl-functionalized polymers for biosensoric applications

The present thesis can be divided in three main parts. In all parts new polymer architecturesrnwere synthesized and characterized concerning their special features.rnThe first part will emphasize the advantage of a polystyrene-block-(hyperbranchedrnpolyglycerol) copolymer in comparison to an analogue polystyrene-block-(linear polyglycerol)rncopolymer. Therefore a synthethic route to prepare linear block copolymersrnhas been developed. Two strategies were examined. One strategy was based on thernclassic, sequential anionic polymerization; the second strategy was based on arn“Click-Chemistry” coupling reaction. In a following step glycidol was hypergraftedrnfrom these block copolymers by applying a hypergrafting reaction with glycidol. Thernbehavior of the amphiphilic block copolymers synthesized was studied in differentrnsolvents. Furthermore the polarity of the solvent was changed to form the correspondingrninverse micelles. DLS, SLS, SEC-MALLS-VISCO, AFM and Cyro TEMrnmeasurements were performed to obtain a visual image from the appearance of thernaggregates. It was found that a linear-hyperbranched architecture is necessary, ifrnwell defined, monodisperse aggregates are required, e.g. for the preparation of orderedrnnanoarrays. Linear-linear block copolymers formed only polydisperse aggregates.rnAdditionally it was found that size distribution could be improved dramaticallyrnby passing the aggregates through a SEC column with large pores. The SEC columnsrnacted like a template in which the aggregates adopt a more stable conformation.rnIn the second part anionic polymerization was employed to synthesize silaneendfunctionalizedrnmacromonomers with different molecular weights based on polybutadienernand polyisoprene. These were polymerized by a hydrosilylation reaction inrnbulk to obtain branched polymers, using Karstedt’s catalyst. Surprisingly the additionrnof monofunctional silanes during the polymerization had only a minimal effect concerningrnthe degree of polymerization. It was possible to introduce silanes without increasingrnthe overall number of reaction steps by a very convenient “pseudo-copolymerization”rnmethod. All branched polymers were analyzed by SEC, SEC-MALLS,rnSEC-viscometry, 1H-NMR-spectroscopy and DSC concerning their branching ratio.rnThe branching parameters for the branched polymers exhibited similar characteristicsrnas hyperbranched polymers based on AB2 monomers. Detailed kinetic study showedrnthat the polymerization occurred very rapidly in comparison to the hydrosilylation polymerizationrnof classical AB2 type carbosilanes monomers.rnThe last part will deal with ferrocenyl-functionalized polymers. On the one hand,rnferrocenyl-functionalized polyglycerols (PG) were studied. Esterification of PGs withrndifferent molecular weight using ferrocenemonocarboxylic acid gave the ferrocenylrnfuntionalized polymers in high yields. On the other hand three different block copolymersrnwere prepared with different ratios of styrene to butadiene units (10:1, 4:1, 2:1).rnThe double bonds of the 1,2-PB block were hydrosilylated using silanes bearing onern(HSiMe2Fc) or two (HSiMeFc2) ferrocene units. High degrees of functionalizationrnwere obtained (up to 83 %). In this manner, six different ferrocenyl-rich block copolymersrnwith different fractions of ferrocene were prepared and analyzed, employingrnNMR-spectroscopy, SEC, SEC/MALLS/viscometry, DLS and cyclic voltammetry. Thernredox properties of the studied polymers varied primarily with the nature of the silanernunit attached. Additionally, the redox properties in solution of the studied polymersrnwere influenced by the block length ratio of the block copolymers. Unexpectedly, withrnincreasing block length of the ferrocenyl block the fraction of active ferrocenes decreased.rnNevertheless, in case of thin monolayer films this behaviour was not observed.rnAll polymers (PG and PS-b-PB based) exhibited good electrochemical propertiesrnin a wide range of solvents, which rendered them very interesting for biosensoricrnapplications.

Synthesis of new calixarene-based lubricant additives

The lubricants are normally composed by base oils and a number of additives which are added to improve the performances of the final product. In this work, which is due to the collaboration between ENI S.p.A. and Prof. Casnati’s group, significant results in the application of calixarene structures to two classes of lubricant additives (viscosity index improvers and detergents) were shown. In particular, several calix[8]arene derivatives were synthesized to use as core precursors in the “arm-first" synthetic processes of star polymers for viscosity index improver applications. The use of calixarene derivatives enable the production of star polymers with a high and well-defined number of branches and endowed with a very low dispersivity of molecular weight which can originate better performances than the current commercially available viscosity index improvers of the major competitor. Several functional groups were considered to prepare reactive p-tert-butylcalix[8]arene cores to be used in living anionic polymerization. n-butyllithium was used as model of the living anionic polymer to test the outcome of the reaction of polymer insertion on the calixarene core, facilitating the analyses of the products. The calixarene derivative, which easier reacts with n-BuLi, was selected for the preparation of star polymers by using a isoprene/styrene living anionic polymer. Finally, the lubricant formulations, which include the calixarene-based star polymers or commercially available products as viscosity index improvers, were prepared and comparatively tested. In the last part of Thesis, the use of calixarenes as polycarboxylic acids to synthetize new sulfur-free detergents as lubricant additives was carried out. In this way, these calcium-based detergents can be used for the formulation of new automotive lubricants with low content of ash, phosphorus and sulfur (low SAPS). To increase the low deprotonation degree of OH groups and their capacity to complex calcium ions, a complete functionalization of the calixarene mixtures with acetic acid groups was required. Futhermore, the “one-step” synthesis of new calixarenes with alkyl chains in para positions longer than the ones already known was necessary to improve the oil solubility and stability of reverse micelles formed by the detergents. Moreover, the separation and characterization of the calixarenes were carried out to optimize their synthetic process, also on pilot scale. For our purpose, the use of p-tert-octylcalixarenes for the preparation of detergents was carried out to compare the properties of the final detergents respect to the use of the p-dodecyl calixarenes. Once achieved the functionalization of both calixarene mixtures with carboxylic acid groups, the syntheses of new calixarene-based detergents were carried out to identify the best calixarene derivative for our research goals. The synthetic process for the preparation of calixarene-based detergent having very high basicity (TBN 400) was also investigated for applications in lubricants for marine engines. In addition, with the aim of testing the calixarene-based detergents in automotive lubricants, several additive packages (concentrated mixture of additives) containing our detergents were prepared. Using these packages the corresponding automotive lubricants can be formulated. Besides, a lubricant containing commercial calcium alkylbenzene-sulfonates detergents was prepared to compare its detergency properties with those of the calixarene-based oils.

Helix-sense-selective polymerization of N,N-diphenyl (meth)acrylamide by anionic catalysts

In this paper, the helix-sense-selective polymerization of N,N-diphenyl acrylamide (DPAA) and N,N-diplienyl methacrylamide(DPMAA) were studied with living helix prepolymer as anionic initiator, and the chiral optical properties of the obtained polymers were investigated too. It was shown that optically active polymers of DPAA and DPMAA could be obtained under the experimental condition, and exhibited the same screw sense as that of the prepolymer.