Correlazioni tra proprietá reologiche, struttura e processabilitá di blend di LLDPE/LDPE

Polymer blends constitute a valuable way to produce relatively low cost new materials. A still open question concerns the miscibility of polyethylene blends. Deviations from the log-additivity rule of the newtonian viscosity are often taken as a signature of immiscibility of the two components. The aim of this thesis is to characterize the rheological behavior in shear and elongation of five series of LLDPE/LDPE blends whose parent polymers have been chosen with different viscosity and SCB content and length. Synergistic effects have been measured for both zero shear viscosity and melt strength. Both SCB length and viscosity ratio between the components have been found to be key parameters for the miscibility of the pure polymers. In particular the miscibility increases with increasing SCB length and with decreasing the LDPE molecular weight and viscosity. This rheological behavior has significant effects on the processability window of these blends when the uni or biaxial elongational flows are involved. The film blowing is one of the processes for which the synergistic effects above mentioned can be crucial. Small scale experiments of film blowing performed for one of the series of blends has demonstrated that the positive deviation of the melt strength enlarges the processability window. In particular, the bubble stability was found to improve or disappear when the melt strength of the samples increased. The blending of LDPE and LLDPE can even reduce undesired melt flow instability phenomena widening, as a consequence, the processability window in extrusion. One of the series of blends has been characterized by means of capillary rheometry in order to allow a careful morphological analysis of the surface of the extruded polymer jets by means of Scanning Electron Microscopy (SEM) with the aim to detect the very early stages of the small scale melt instabilty at low shear rates (sharksin) and to follow its subsequent evolution as long as the shear rate was increased. With this experimental procedure it was possible to evaluate the shear rate ranges corresponding to different flow regions: smooth extrudate surface (absence of instability), sharkskin (small scale instability produced at the capillary exit), stick-slip transition (instability involving the whole capillary wall) and gross melt fracture (i.e. a large scale "upstream" instability originating from the entrance region of the capillary). A quantitative map was finally worked out using which an assessment of the flow type for a given shear rate and blend composition can be predicted.

Synthese und Charakterisierung von Poly(tert-butylacrylat)- und Polyacrylsäure-Sternpolymeren

Sternpolymere aus Poly(tert.-butylacrylat)-Armen und einem Mikrogel-Core aus Ethylenglykoldimethacrylat wurden nach der arm-first Strategie hergestellt. Diese weisen eine enge Armzahlverteilung auf. Mit sinkender Precursorlänge, mit steigendem Verhältnis [bifunktionelles Monomer]/[Initiator], sowie mit zunehmender Reaktionszeit und Gesamtkonzentration nimmt die mittlere Armzahl fn zu. Die Sternbildung verläuft ähnlich einer Polykondensation. Die Molekulargewichte wurden mittels GPC gekoppelt mit einem online-Viskosimeter und einem online-Vielwinkellichtstreudetektor (MALLS) bestimmt.Die intrinsischen Viskositäten der Sternpolymere sind sehr niedrig. Für Armzahlen f ca. 8 erhält man ein Maximum in der doppellogarithmischen Auftragung der intrinsischen Viskosität und des Molekulargewichts. Die Trägheitsradien nehmen nur wenig mit dem Molekulargewicht zu. Die erhaltenen Koeffizienten liegen im von Daoud und Cotton vorhergesagten Bereich. Die Schrumpfungsfaktoren sinken auf g ca. 0,2 bzw. g' ca. 0,25. Aus den Poly(tert.-butylacrylat)-Sternpolymeren wurden durch Verseifung mit HBr in Methanol Polyacrylsäure-Sternpolymere hergestellt, welche ebenfalls mittels GPC-Viskosimetrie und GPC-MALLS charakterisiert wurden. Für die ionischen Sternpolymere findet man deutlich höhere Schrumpfungsfaktoren, kein Maximum in der intrinsischen Viskosität und höhere Exponenten als von Daoud und Cotton vorhergesagt. Erklärt wurde dies mit der hohen Segmentdichte in Sternpolymeren, die bei den ionischen Sternpolymeren zu einer hohen Ladungsdichte führt. Dadurch müssen sich die Arme stärker strecken als bei nicht-ionischen Sternen und es resultieren größere Moleküldimensionen.

Kinetische Untersuchungen zur Synthese von Blockcopolymeren mit Methacrylatsegmenten durch neue anionische Polymerisationssysteme

Ein metallfreies Reaktionssystem mit Bis(triphenylphosphoranyliden)ammonium-Kationen als Gegenionen sowie das Additiv Lithium-2-methoxyethoxid wurden auf ihre Eignung zur anionischen Synthese von Blockcopolymeren mit (Meth)acrylatsegmenten bei moderaten Temperaturen im Strömungsrohr-Reaktor untersucht. Das metallfreie System ist zur lebenden Polymerisation von Methacrylaten in THF mit engen Molekulargewichtsverteilungen bei Reaktionszeiten < 1 s bis zu Temperaturen von 0 °C geeignet. In Gegenwart von Metallionen (Li+) findet eine Verlangsamung der Polymerisation unter Verlust der Reaktionskontrolle statt, Lithiumenolate verursachen nun breite, multimodale Molekulargewichtsverteilungen. Eine lebende Polymerisation von Acrylaten ist nicht möglich, massenspektroskopische Untersuchungen der Produkte weisen auf einen komplexen Reaktionsmechanismus mit Abbruch- und Übertragungsreaktionen hin. Die Synthese von Poly(styrol)-block-Poly(1,4-butadien)-block-Poly(methylmethacrylat)-Copolymeren in Toluol ist mit Lithium-2-methoxyethoxid als Additiv für die MMA-Polymerisation bei moderaten Mischtemperaturen (T < 0 °C) im Strömungsrohr-Reaktor möglich, die Effektivität des Wechselschritts von Polybutadien zu PMMA beträgt im Durchschnitt ca. 50 %. Untersuchungen verschiedener Reaktionsparameter, wie z.B. der Endfunktionalisierung des Polybutadiens mit 1,1-Diphenylethylen und der Temperatur während der Verkappung und der MMA-Polymerisation, geben keine eindeutigen Hinweise auf die Ursache dieses Phänomens. MALDI-TOF-Massenspektren des unreagierten Polybutadien Precursors zeigen die Anlagerung von 1-3 Molekülen Methylmethacrylat und keinen Abbruch durch Backbiting, was auf die Ausbildung stabiler Aggregate hindeutet.

Cellulose based Lithium ion polymer electrolytes for Lithium batteries

The separator membrane in batteries and fuel cells is of crucial importance for the function of these devices. In lithium ion batteries the separator membrane as well as the polymer matrix of the electrodes consists of polymer electrolytes which are lithium ion conductors. To overcome the disadvantage of currently used polymer electrolytes which are highly swollen with liquids and thus mechanically and electrochemically unstable, the goal of this work is a new generation of solid polymer electrolytes with a rigid backbone and a soft side chain structure. Moreover the novel material should be based on cheap substrates and its synthesis should not be complicated aiming at low overall costs. The new materials are based on hydroxypropylcellulose and oligoethyleneoxide derivatives as starting materials. The grafting of the oligoethyleneoxide side chains onto the cellulose was carried out following two synthetic methods. One is based on a bromide derivative and another based on p-toluolsulfonyl as a leaving group. The side chain reagents were prepared form tri(ethylene glycol) monoethyl ether. In order to improve the mechanical properties the materials were crosslinked. Two different conceptions have been engaged based on either urethane chemistry or photosensitive dimethyl-maleinimide derivatives. PEO - graft - cellulose derivatives with a high degree of substitution between 2,9 and 3,0 were blended with lithium trifluoromethane-sulfonate, lithium bis(trifluorosulfone)imide and lithium tetrafluoroborate. The molar ratios were in the range from 0,02 to 0,2 [Li]/[O]. The products have been characterized with nuclear magnetic resonance (NMR), gel permeation chromatography (GPC) and laserlight scattering (LS) with respect to their degree of substitution and molecular weight. The effect of salt concentration on ionic conductivity, thermal behaviour and morphology has been investiga-ted with impedance spectroscopy, differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The crosslinking reactions were controlled with dynamic mechanical analysis (DMS). The degree of substitution of our products is varying between 2,8 and 3,0 as determined by NMR. PEO - graft - cellulose derivatives are highly viscous liquids at room temperature with glass transition temperatures around 215 K. The glass transition temperature for the Lithium salt complexes of PEO - graft - cellulose deri-vatives increase with increasing salt content. The maximum conductivity at room temperature is about 10-4 and at 100°C around 10-3 Scm-1. The presence of lithium salt decreases the thermal stability of the complexes in comparison to pure PEO - graft - cellulose derivatives. Complexes heated over 140 – 150°C completely lose their ionic conductivity. The temperature dependence of the conductivity presented as Arrhenius-type plots for all samples is similar in shape and follows a VTF behaviour. This proofs that the ionic transport is closely related to the segmental motions of the polymer chains. Novel cellulose derivatives with grafted oligoethylen-oxide side chains with well-defined chemical structure and high side chain grafting density have been synthesized. Cellulose was chosen as stiff, rod like macromolecule for the backbone while oligoethylen-oxides are chosen as flexible side chains. A maximum grafting density of 3.0 have been obtained. The best conductivity reaches 10-3 Scm-1 at 100°C for a Li-triflate salt complex with a [Li]/[O] ratio of 0.8. The cross-linked complexes containing the lithium salts form elastomeric films with convenient mechanical stability. Our method of cellulose modification is based on relatively cheap and commercially available substrates and as such appears to be a promising alternative for industrial applications.

Synthesis and characterization of novel poly(imino ketone)s via palladium-catalyzed aryl amination

The challenge of the present work was to synthesize and to characterize new classes of N-containing polymers via palladium-catalyzed aryl amination. This work was inspired by a desire to combine the properties of high-performance polymers such as PEKs with those of N-containing conductive polymers such as polyaniline (PANI), poly(aromatic amides) (PAAs), and the ready synthesis of N-containing simple aromatic compound by the Buchwald-Hartwig reaction. Careful investigation of a model reaction was carried out to provide insights into the formation of side products which will have a negative effect upon the molecular weight or upon the materials properties of the desired polymers in the polycondensation reaction. In this thesis, five new different polymer classes namely, poly(imino ketone)s (PIKs), poly(imino acridine)s (PIAcs), poly(imino azobenzene)s (PIAzos), poly(imino fluorenone)s (PIFOs), and poly(imino carbazole)s (PICs) were synthesized and fully characterized by means of 1H-NMR, elemental analysis, UV, FT-IR, X-ray, GPC, TGA, DSC, DMA, and dielectric spectroscopy. To optimize the polycondensation process, the influence of the concentration, temperature, ligands and the reactivity of the halogen containing monomers were investigated. A temperature of 100-165 °C and a concentration of 30-36 % were found to be optimal for the palladium-catalyzed polycondensation to produce polymer with high molecular weight (Mn = 85 900, Mw = 474 500, DP = 126). Four different ligands were used successfully in the Pd-catalyzed process, of which the Pd/BINAP system was found to be the most effective catalyst, producing the highest yield and highest molecular weight polymers. It was found that the reactivity decreases strongly with increasing electronegativity of the halogen atoms, for example better yields, and higher molecular weights were obtained by using dibromo compounds than dichloro compounds while difluoro compounds were totally unreactive. Polymer analogous transformations, such as the protonation reaction of the ring nitrogens in PIAcs, or of the azobenzene groups of PIAzos, the photo and thermal cis-trans-isomerization of PIAzos, and of poly(imino alcohol)s were also studied. The values of the dielectric constants of PIKs at 1 MHz were in the range 2.71-3.08. These low values of the dielectric constant are lower than that of "H Film", a polyimide Kapton film which is one of the most preferred high-performance dielectrics in microelectronic applications having a dielectric constant of 3.5. In addition to the low values of the dielectric constants, PIKs have lower and glass transition temperatures (Tgs) than arimides such as Kapton which may make them more easily processable. Cyclic voltammetry showed that PICs exhibited low oxidation and reduction potentials and their values were shifted to low values with increasing degree of polymerization i.e. with increasing of the carbazole content in backbone of PICs (PIC-7, 0.44, 0.33 V, DP= 37, PIC-5, 0.63, 0.46, DP= 16, respectively).

New synthetic strategies to tethered bilayer lipid membranes

Tethered bilayer lipid membranes provide an efficient, stable and versatile platform for the investigation of integrated membrane proteins. However, the incorporation of large proteins, as well as of proteins with a large submembrane part is still a very critical issue and therefore, further optimisation of the system is necessary. The central element of a tBLM is a lipid bilayer. Its proximal leaflet is, at least to some extend, covalently attached to a solid support via a spacer group. The anchor lipid consists of three distinct parts, a lipid headgroup, a spacer group and an anchor. All parts together influence the final bilayer properties. In the frame of this work, the synthesis of new thiolipids for tBLMs on gold has been investigated. The aim was to obtain molecules with longer spacers in order to increase the submembrane space. The systems obtained have been characterized using SPR and EIS. The results obtained during this study are multiple. First, the synthesis of a previously synthesized architecture was successfully scaled up in an industrial lab using a new synthetic approach. The synthesis of large amounts is now feasible. Then, the synthesis of the new thiolipids was carried out taking into account the following requirements: the increase of the submembrane space by having longer ethyleneglycol spacers, the attachment of the molecules to a gold substrate via a thiol bond, and the tunability of the lateral mobility by changing the lipid headgroup. Three different synthetic strategies have been investigated. The polymeric approach did not prove to be successful, merely because of the broad molecular weight distribution. The synthesis of heterofunctionally protected oligoethyleneglycols allowed to obtain ethyleneglycol moieties with 6 and 8 units, but the tedious purification steps gave very low yields. Finally, the block by block synthesis using ethyleneglycol precursors proved to be an efficient and fast method to synthesize the target molecules. Indeed, these were obtained with very high yields, and the separation was very efficient. A whole family of new compounds was obtained, having 6, 8 and 14 ethyleneglycol units and with mono- or diphytanyl lipid headgroups. This new pathway is a very promising synthetic strategy that can be used further in the development of new compounds of the tether system. The formation of bilayers was investigated for the different thiolipids mainly by using EIS. The electrical properties of a bilayer define the quality of the membrane and allow the study of the functionality of proteins embedded in such a system. Despite multiple trials to improve the system using self assembly, Langmuir Blodgett transfer, and detergent mixed vesicles, the new polymer thiolipids did not show as high electrical properties as tBLMs reported in the literature. Nevertheless, it was possible to show that a bilayer could be obtained for the different spacer lengths. These bilayers could be formed using self assembly for the first monolayer, and two different methods for bilayer formation, namely vesicle fusion and solvent exchange. We could furthermore show functional incorporation of the ion carrier valinomycin: the selective transport of K+ ions could be demonstrated. For DPHL, it was even possible to show the functional incorporation of the ion channel gramicidin. The influence of the spacer length is translated into an increase of the spacer capacitance, which could correspond to an increase in the capacity of charge accumulation in the submembrane space. The different systems need to be further optimised to improve the electrical properties of the bilayer. Moreover, the incorporation of larger proteins, and proteins bearing submembrane parts needs to be investigated.

Reverse genetic studies of Benyvirus - Polymyxa betae molecular interaction: Role of the RNA4-encoded protein in virus transmission

Beet necrotic yellow vein virus (BNYVV), the leading infectious agent that affects sugar beet, is included within viruses transmitted through the soil from plasmodiophorid as Polymyxa betae. BNYVV is the causal agent of Rhizomania, which induces abnormal rootlet proliferation and is widespread in the sugar beet growing areas in Europe, Asia and America; for review see (Peltier et al., 2008). In this latter continent, Beet soil-borne mosaic virus (BSBMV) has been identified (Lee et al., 2001) and belongs to the benyvirus genus together with BNYVV, both vectored by P. betae. BSBMV is widely distributed only in the United States and it has not been reported yet in others countries. It was first identified in Texas as a sugar beet virus morphologically similar but serologically distinct to BNYVV. Subsequent sequence analysis of BSBMV RNAs evidenced similar genomic organization to that of BNYVV but sufficient molecular differences to distinct BSBMV and BNYVV in two different species (Rush et al., 2003). Benyviruses field isolates usually consist of four RNA species but some BNYVV isolates contain a fifth RNA. RNAs -1 contains a single long ORF encoding polypeptide that shares amino acid homology with known viral RNA-dependent RNA polymerases (RdRp) and helicases. RNAs -2 contains six ORFs: capsid protein (CP), one readthrough protein, triple gene block proteins (TGB) that are required for cell-to-cell virus movement and the sixth 14 kDa ORF is a post-translation gene silencing suppressor. RNAs -3 is involved on disease symptoms and is essential for virus systemic movement. BSBMV RNA-3 can be trans-replicated, trans-encapsidated by the BNYVV helper strain (RNA-1 and -2) (Ratti et al., 2009). BNYVV RNA-4 encoded one 31 kDa protein and is essential for vector interactions and virus transmission by P. betae (Rahim et al., 2007). BNYVV RNA-5 encoded 26 kDa protein that improve virus infections and accumulation in the hosts. We are interest on BSBMV effect on Rhizomania studies using powerful tools as full-length infectious cDNA clones. B-type full-length infectious cDNA clones are available (Quillet et al., 1989) as well as A/P-type RNA-3, -4 and -5 from BNYVV (unpublished). A-type BNYVV full-length clones are also available, but RNA-1 cDNA clone still need to be modified. During the PhD program, we start production of BSBMV full-length cDNA clones and we investigate molecular interactions between plant and Benyviruses exploiting biological, epidemiological and molecular similarities/divergences between BSBMV and BNYVV. During my PhD researchrs we obtained full length infectious cDNA clones of BSBMV RNA-1 and -2 and we demonstrate that they transcripts are replicated and packaged in planta and able to substitute BNYVV RNA-1 or RNA-2 in a chimeric viral progeny (BSBMV RNA-1 + BNYVV RNA-2 or BNYVV RNA-1 + BSBMV RNA-2). During BSBMV full-length cDNA clones production, unexpected 1,730 nts long form of BSBMV RNA-4 has been detected from sugar beet roots grown on BSBMV infected soil. Sequence analysis of the new BSBMV RNA-4 form revealed high identity (~100%) with published version of BSBMV RNA-4 sequence (NC_003508) between nucleotides 1-608 and 1,138-1,730, however the new form shows 528 additionally nucleotides between positions 608-1,138 (FJ424610). Two putative ORFs has been identified, the first one (nucleotides 383 to 1,234), encode a protein with predicted mass of 32 kDa (p32) and the second one (nucleotides 885 to 1,244) express an expected product of 13 kDa (p13). As for BSBMV RNA-3 (Ratti et al., 2009), full-length BSBMV RNA-4 cDNA clone permitted to obtain infectious transcripts that BNYVV viral machinery (Stras12) is able to replicate and to encapsidate in planta. Moreover, we demonstrated that BSBMV RNA-4 can substitute BNYVV RNA-4 for an efficient transmission through the vector P. betae in Beta vulgaris plants, demonstrating a very high correlation between BNYVV and BSBMV. At the same time, using BNYVV helper strain, we studied BSBMV RNA-4’s protein expression in planta. We associated a local necrotic lesions phenotype to the p32 protein expression onto mechanically inoculated C. quinoa. Flag or GFP-tagged sequences of p32 and p13 have been expressed in viral context, using Rep3 replicons, based on BNYVV RNA-3. Western blot analyses of local lesions contents, using FLAG-specific antibody, revealed a high molecular weight protein, which suggest either a strong interaction of BSBMV RNA4’s protein with host protein(s) or post translational modifications. GFP-fusion sequences permitted the subcellular localization of BSBMV RNA4’s proteins. Moreover we demonstrated the absence of self-activation domains on p32 by yeast two hybrid system approaches. We also confirmed that p32 protein is essential for virus transmission by P. betae using BNYVV helper strain and BNYVV RNA-3 and we investigated its role by the use of different deleted forms of p32 protein. Serial mechanical inoculation of wild-type BSBMV on C. quinoa plants were performed every 7 days. Deleted form of BSBMV RNA-4 (1298 bp) appeared after 14 passages and its sequence analysis shows deletion of 433 nucleotides between positions 611 and 1044 of RNA-4 new form. We demonstrated that this deleted form can’t support transmission by P. betae using BNYVV helper strain and BNYVV RNA-3, moreover we confirmed our hypothesis that BSBMV RNA-4 described by Lee et al. (2001) is a deleted form. Interesting after 21 passages we identifed one chimeric form of BSBMV RNA-4 and BSBMV RNA-3 (1146 bp). Two putative ORFs has been identified on its sequence, the first one (nucleotides 383 to 562), encode a protein with predicted mass of 7 kDa (p7), corresponding to the N-terminal of p32 protein encoded by BSBMV RNA-4; the second one (nucleotides 562 to 789) express an expected product of 9 kDa (p9) corresponding to the C-terminal of p29 encoded by BSBMV RNA-3. Results obtained by our research in this topic opened new research lines that our laboratories will develop in a closely future. In particular BSBMV p32 and its mutated forms will be used to identify factors, as host or vector protein(s), involved in the virus transmission through P. betae. The new results could allow selection or production of sugar beet plants able to prevent virus transmission then able to reduce viral inoculum in the soil.

Entwicklung neuartiger stickstoffreicher Polyphenylene

Im Rahmen dieser Arbeit wurden Darstellung und elektronische Anwendungsmöglichkeiten von neuartigen stickstoff- und damit elektronenreichen Poly(para-phenylenen) untersucht. Der Teilbereich „Polycarbazole“ befasst sich mit der Synthese von konjugierten (Stufen)leiterpolymeren auf der Basis von Carbazol. Dazu wurde ein neuer und effizienter Syntheseweg zur Gewinnung von 2,7-Dibromcarbazol entwickelt. Durch die weitere Funktionalisierung von 2,7-Dibromcarbazol gelang es, elektronenreiche Leiterpolymere zu gewinnen, die eine grüne Emissionsfarbe aufwiesen. Mit der Verwendung von R = 2-Decyltetradecyl als löslichkeitsfördernder Seitenkette in einem Poly(2,7-carbazol) konnte erstmals ein hochmolekulares Polycarbazol gewonnen werden. Dieses gut lösliche Poly(2,7-carbazol) erwies sich als ein exzellentes Donatormaterial in Solarzellen, welches in Kombination mit dem Farbstoff PDI eine effiziente Solarzelle ergab. Eine OLED mit einem neuartigen arylierten Polycarbazol als Emittermaterial zeigte eine sehr niedrige Turn-on-Spannung und eine intensive blaue EL-Emission. Das Kapitel über imidazolhaltige Poly(para-phenylene) und Discoten stellt die Darstellung von planarisierten Bisimidazolen vor, welche in hohen Ausbeuten durch eine intramolekulare Buchwald-Reaktion zwischen den Imidazolringen und der zentralen Terphenyleinheit durchgeführte wurde. Die dreistufige Darstellung der Discoten aus einem Terephthalaldehyd-Derivat und einem Benzil erlaubt eine einfache sowie variable Einführung von löslichkeitsfördernden Alkylsubstituenten. Auf diese Weise ist der Zugang zu einer völlig neuartigen Klasse an discotischen Materialien möglich, die eine Kombination aus Discoten auf der Basis von Benzolringen (wie z.B. HBC) mit Heteroaromaten darstellen. Die gewonnenen scheibenförmigen Bisimidazole wiesen dementsprechend auf Selbstanordnung zurückzuführende kolumnare Anordnungen und hexagonale Überstrukturen auf. Im dritten Themengebiet wird der Einbau eines Phthalimidchromophors direkt in das Rückgrad von Polyanilin vorgestellt. Da jegliche Veränderung des Oxidationsgrades zu einer unterschiedlichen Donatorfähigkeit des Polyanilinhauptkette führt, variiert in Abhängigkeit davon das Absorptionsverhalten des eingebauten Farbstoffes. Durch die Einführung des Phthalimidchromophores war es zudem möglich, ein leitfähiges Polymer zu erhalten, das im Gegensatz zum nicht-fluoreszierenden Polyanilin eine intensive gelbe Fluoreszenz (lmax = 547 nm) aufweist.

1-, 2- and 3-dimensional phenylene-based materials for optoelectronic applications

A series of oligo-phenylene dendronised conjugated polymers was prepared. The divergent synthetic approach adopted allowed for the facile synthesis of a range of dendronised monomers from a common intermediate, e.g. first and second generation fluorene. Only the polymerisation of the first generation and alkylarylamine substituted dendronised fluorene monomers yielded high molecular weight materials, attributed to the low solubility of the remaining dendronised monomers. The alkylarylamine substituted dendronised poly(fluorene) was incorporated into an organic light emitting diode (OLED) and exhibited an increased colour stability in air compared to other poly(fluorenes). The concept of dendronisation was extended to poly(fluorenone), a previously insoluble material. The synthesis of the first soluble poly(fluorenone) was achieved by the incorporation of oligo-phenylene dendrons at the 4-position of fluorenone. The dendronisation of fluorenone allowed for a polymer with an Mn of 4.1 x 104 gmol-1 to be prepared. Cyclic voltammetry of the dendronised poly(fluorenone) showed that the electron affinity of the polymer was high and that the polymer is a promising n-type material. A dimer and trimer of indenofluorene (IF) were prepared from the monobromo IF. These oligomers were investigated by 2-dimensional wide angle x-ray spectroscopy (2D-WAXS), polarised optical microscopy (POM) and dielectric spectroscopy, and found to form highly ordered smetic phases. By attaching perylene dye as the end-capper on the IF oligomers, molecules that exhibited efficient Förster energy transfer were obtained. Indenofluorene monoketone, a potential defect structure for IF based OLED’s, was synthesised. The synthesis of this model defect structure allowed for the long wavelength emission in OLED’s to be identified as ketone defects. The long wavelength emission from the indenofluorene monoketone was found to be concentration dependent, and suggests that aggregate formation is occurring. An IF linked hexa-peri-hexabenzocoronene (HBC) dimer was synthesised. The 2D-WAXS images of this HBC dimer demonstrate that the molecule exhibits intercolumnar organisation perpendicular to the extrusion direction. POM images of mixtures of the HBC dimer mixed with an HBC with a low isotropic temperature demonstrated that the HBC dimer is mixing with the isotropic HBC.

Structure and properties of composite polyolefin materials

This thesis is based on three main studies, all dealing with structure-property investigation of semicrystalline polyolefin-based composites. Low density poly(ethylene) (LDPE) and isotactic poly(propylene) (iPP) were chosen as parts of the composites materials and they were investigated either separately (as homoploymers), either in blend systems with the composition LDPE/iPP 80/20 or as filled matrix with layered silicate (montmorillonite). The beneficial influence of adding ethylene-co-propylene polymer of amorphous nature, to low density poly(ethylene)/isotactic poly(propylene) (80/20) blend is demonstrated. This effect is expressed by the major improvement of mechanical properties of ternary blends as examined at a macroscopic size scale by means of tensile measurements. The structure investigation also reveals a clear dependence of the morphology on adding ethylene-copropylene polymer. Both the nature and the content of ethylene-co-propylene polymer affect structure and properties. It is further demonstrated that the extent of improvement in mechanical properties is to be related to the molecular details of the compatibilizer. Combination of high molecular weight and high ethylene content is appropriate for the studied system where the poly(ethylene) plays the role of matrix. A new way to characterize semicrystalline systems by means of Brillouin spectroscopy is presented in this study. By this method based on inelastic light scattering, we were able to measure the high frequency elastic constant (c11) of the two microphases in the case where the spherulites size is exhibit size larger than the size of the probing phonon wavelength. In this considered case, the sample film is inhomogeneous over the relevant length scales and there is an access to the transverse phonon in the crystalline phase yielding the elastic constant c44 as well. Isotactic poly(propylene) is well suited for this type of investigation since its morphology can be tailored through different thermal treatment from the melt. Two distinctly different types of films were used; quenched (low crystallinity) and annealed (high crystallinity). The Brillouin scattering data are discussed with respect to the spherulites size, lamellae thickness, long period, crystallinity degree and well documented by AFM images. The structure and the properties of isotactic poly(propylene) matrix modified by inorganic layered silicate, montmorillonite, are discussed with respect to the clay content. Isotactic poly(propylene)-graft-maleic anhydride was used as compatibilizer. It is clearly demonstrated that the property enhancement is largely due to the ability of layered silicate to exfoliate. The intimate dispersion of the nanometer-thick silicate result from a delicate balance of the content ratio between the isotactic poly(propylene)-graft-maleic anhydride compatibilizer and the inorganic clay.

Sprühgetrocknete Polylaktid, Poly(laktid-co-glykolid) Mikropartikel zur Steuerung der Freisetzung aus pulmonalen Arzneiformen

Zusammenfassung Die vorliegende Arbeit hat zum Ziel, pharmazeutisch-technologische Möglichkeiten der Retardierung bei ausgewählten Antiasthmatika zur pulmonalen Applikation anzuwenden. Dafür sollten Mikropartikel hergestellt und pharmazeutisch sowie biopharmazeutisch charakterisiert werden. Als Modellsubstanzen werden das Glukokortikoid Budesonid und das β2-Sympathomimetikum Salbutamol in Form seiner Base und seines Salzes verwendet. Die Auswahl erfolgt nach physikochemischen (Lipophilie, Molekulargewicht) und therapeutischen (Halbwertszeit der Wirkung, Applikationsfrequenz) Gesichtspunkten. Mikropartikel auf Polymerbasis ermöglichen eine kontrollierte Freigabe der Arzneistoffe über einen vorausbestimmten Zeitraum. Es erfolgt die Auswahl physiologisch unbedenklicher Hilfsstoffe (Polylaktide R 202H/ Poly(laktid-co-glykolide) RG 502H, RG 752-S) mit unterschiedlichen Anteilen an Coglykolid sowie unterschiedlichen Molekulargewichten, die sich prinzipiell zur Verzögerung der Freisetzung eignen und sich bei der parenteralen Applikation bereits bewährt haben. Die Sprühtrocknung wird als geeignetes pharmazeutisch-technologisches Verfahren zur Präparation von Mikropartikeln im Teilchengrößenbereich von 1- 10 Mikrometern beschrieben, welche den Wirkstoff mit möglichst hoher Beladung verkapselt. Die sprühgetrockneten Pulver sollen pharmazeutisch physikochemisch mittels Rasterelektronenmikroskopie (Morphologie), Laserdiffraktometrie (Teilchengrößenverteilung), DSC und Röntgenpulverdiffraktometrie (thermisches Verhalten) und mittels Stickstoff-Tief-Temperatur Adsorptionsverfahren (spezifische Oberfläche) charakterisiert werden. Zusätzlich wird die Wirkstoffbeladung der sprühgetrockneten Polymer-Mikropartikel mittels HPLC ermittelt. Die biopharmazeutische Charakterisierung der sprühgetrockneten Pulver erfolgt über die in-vitro Freigabekinetik und die Stabilität der Mikropartikel. Zusätzlich werden Versuche an Zellkulturen und in-vivo Versuche an Mäusen durchgeführt, um die Effekte der sprühgetrockneten Mikropartikel und des Hilfsstoffs hinsichtlich der Freisetzungsretardierung zu testen. Bei den in-vivo Versuchen werden der Atemwegswiderstand und die Verlängerung der exspiratorischen Phase (penh) als Parameter für einen antiasthmatischen Effekt gewählt. Die Lungenlavage Flüssigkeit wird zusätzlich überprüft. Die Ergebnisse zeigen, dass es mit Hilfe der Sprühtrocknung möglich ist, Polymer-Mikropartikel herzustellen, die aufgrund ihrer Partikelgröße von d50 ≤ 5,8 µm fähig sind, die unteren Abschnitte der Lunge zu erreichen. Die Morphologie der Mikropartikel ist abhängig vom zu versprühenden Produkt. Thermodynamisch und röntgenpulverdiffraktometrisch betrachtet handelt es sich um amorphe Produkte, die aber über lange Zeit in diesem Zustand stabil sind. Die Wiederfindung der eingesetzten Arzneistoffmenge in den sprühgetrockneten Polymer-Mikropartikeln und die Freigabeversuche zur Charakterisierung der Retardierungseigenschaften der verwendeten Polymere ergeben, dass es mit Hilfe der Sprühtrocknung von Budesonid und Salbutamol mit den Polymeren möglich ist, retardierende Mikropartikel herzustellen. Die Wiederfindung von Budesonid und Salbutamol in den sprühgetrockneten Polymer-Mikropartikeln entspricht nahezu der eingesetzten Menge. Bei Salbutamolsulfat ist dies nicht der Fall. In Zellkulturversuchen der murinen Zellinie RAW 264.7 ergaben sich Hinweise darauf, dass bei Konzentrationen von 10-6 M und 10-8 M, die Downregulation der IL-6 Konzentration durch die Sprüheinbettung von 9,1 % Budesonid mit PLGA in stärkerem Ausmaß erfolgte, als bei unverkapseltem Budesonid. Zusätzlich wurden in-vivo Versuche mit intranasaler und intraperitonealer Gabe durchgeführt. Die Budesonid-Polymer Sprüheinbettung wurde mit unverkapseltem Budesonid vergleichen. Nach intraperitonealer Gabe hatte die Sprüheinbettung mit Budesonid die besten Effekte hinsichtlich der Unterdrückung des penh und des Atemwegswiderstands auch bei steigenden Metacholinkonzentrationen. Die Auswertung der Lungenlavage Flüssigkeit zeigt sehr deutlich die Downregulation der IL-6 Konzentration in der Lunge durch die Sprüheinbettung mit Budesonid. Zur Zeit werden Vorbereitungen getroffen, ein Gerät zu testen, das in der Lage ist, ein Mikrospray zu generieren, so dass eine intratracheale Verabreichung möglich wäre.

Modeling of complex chemical reactions and macromolecular orientation phenomena in confined geometries

The cooperative motion algorithm was applied on the molecular simulation of complex chemical reactions and macromolecular orientation phenomena in confined geometries. First, we investigated the case of equilibrium step-growth polymerization in lamellae, pores and droplets. In such systems, confinement was quantified as the area/volume ratio. Results showed that, as confinement increases, polymerization becomes slower and the average molecular weight (MW) at equilibrium decreases. This is caused by the sterical hindrance imposed by the walls since chain growth reactions in their close vicinity have less realization possibilities. For reactions inside droplets at surfaces, contact angles usually increased after polymerization to compensate conformation restrictions imposed by confinement upon growing chains. In a second investigation, we considered monodisperse and chemically inert chains and focused on the effect of confinement on chain orientation. Simulations of thin polymer films showed that chains are preferably oriented parallel to the surface. Orientation increases as MW increases or as film thickness d decreases, in qualitative agreement with experiments with low MW polystyrene. It is demonstrated that the orientation of simulated chains results from a size effect, being a function of the ratio between chain end-to-end distance and d. This study was complemented by experiments with thin films of pi-conjugated polymers like MEH-PPV. Anisotropic refractive index measurements were used to analyze chain orientation. With increasing MW, orientation is enhanced. However, for MEH-PPV, orientation does not depend on d even at thicknesses much larger than the chain contour length. This contradiction with simulations was discussed by considering additional causes for orientation, for instance the appearance of nematic-like ordering in polymer films. In another investigation, we simulated droplet evaporation at soluble surfaces and reproduced the formation of wells surrounded by ringlike deposits at the surface, as observed experimentally. In our simulations, swollen substrate particles migrate to the border of the droplet to minimize the contact between solvent and vacuum, which costs the most energy. Deposit formation in the beginning of evaporation results in pinning of the droplet. When polymer chains at the substrate surface have strong uniaxial orientation, the resulting pattern is no longer similar to a ring but to a pair of half-moons. In a final stage, as an extension for the model developed for polymerization in nanoreactors, we studied the effect of geometrical confinement on a hypothetical oscillating reaction following the mechanism of the so called periodically forced Brusselator. It was shown that a reaction which is chaotic in the bulk may be driven to periodicity by confinement and vice-versa, opening new perspectives for chaos control.

Proteine im Wein

Untersucht wird die Proteinzusammensetzung verschiedener Weinsorten der Anbaugebiete Rheinhessen, Rheingau und Pfalz. Es erfolgt erstmalig die Identifizierung der Proteine eines Rotweins (Portugieser 2005 aus der Pfalz). Hierzu werden die Proteine mittels Dialyse und Gefriertrocknung konzentriert, auf einer SDS-PAGE aufgetrennt und mittels ESI-Q-TOF-Massenspektrometrie identifiziert. Von den identifizierten Proteinen des Rotweins stammen zwölf aus der Weinbeere und sechs werden im Laufe der Weinbereitung durch die Hefe ein-gebracht. Der Großteil der über die Weinbeere in den Wein gelangten Proteine ist der Gruppe der Pathogenese bezogenen Proteine zuzuordnen. Ein Vergleich der Proteinzusammensetzung verschiedener Rotweine, Weißweine und Rosé-weine zeigt, dass ein gemeinsames Proteinspektrum in allen Weinsorten enthalten ist, es je-doch auch Unterschiede hinsichtlich der Proteinzusammensetzung und Konzentration der ein-zelnen Proteine zwischen den Rebsorten, insbesondere roten und weißen, gibt. In Portugieser Rotwein des Jahrgangs 2005 aus der Pfalz sowie in Dornfelder Rotwein der Jahrgänge 2002, 2003, 2004 und 2005 kann das als Allergen beschriebene Lipid Transfer Pro-tein (Isoform 4) nachgewiesen werden. In den untersuchten Weißweinsorten Riesling, Sau-vignon Blanc, Morio Muskat sowie Gewürztraminer ist dieses nicht bzw. nur in sehr geringen Mengen enthalten. Ebenfalls nur in Rotwein wird eine Klasse IV Endochitinase identifiziert, die als Allergen in jungem Rotwein bereits beschrieben wurde. Außerdem bedingen Chitin-asen zusammen mit den Thaumatin-ähnlichen Proteinen die Proteininstabilität. Thaumatin-ähnliche Proteine stellen in allen Weinsorten den größten Anteil der Proteine dar. Viele der Weinproteine liegen in glykosylierter Form vor, was durch die Perjodsäurefärbung und den Lektinblot gezeigt werden kann. Mit der Detektion von Thaumatin-ähnlichen Proteinen, Lipid Transfer Proteinen sowie einer Endochitinase werden potentielle Allergene im Wein nachgewiesen sowie strukturell mit be-kannten Allergenen verglichen. Die Kenntnis der Proteinzusammensetzung im Wein bildet die Grundlage für weiterführende Untersuchungen zur Weinstabilität und zur Allergenität von Weinproteinen.

Development and applications of hollow fiber flow field-flow fractionation in the bioanalytical field. Studies of aggregation phenomena in complex protein samples

Recent advances in the fast growing area of therapeutic/diagnostic proteins and antibodies - novel and highly specific drugs - as well as the progress in the field of functional proteomics regarding the correlation between the aggregation of damaged proteins and (immuno) senescence or aging-related pathologies, underline the need for adequate analytical methods for the detection, separation, characterization and quantification of protein aggregates, regardless of the their origin or formation mechanism. Hollow fiber flow field-flow fractionation (HF5), the miniaturized version of FlowFFF and integral part of the Eclipse DUALTEC FFF separation system, was the focus of this research; this flow-based separation technique proved to be uniquely suited for the hydrodynamic size-based separation of proteins and protein aggregates in a very broad size and molecular weight (MW) range, often present at trace levels. HF5 has shown to be (a) highly selective in terms of protein diffusion coefficients, (b) versatile in terms of bio-compatible carrier solution choice, (c) able to preserve the biophysical properties/molecular conformation of the proteins/protein aggregates and (d) able to discriminate between different types of protein aggregates. Thanks to the miniaturization advantages and the online coupling with highly sensitive detection techniques (UV/Vis, intrinsic fluorescence and multi-angle light scattering), HF5 had very low detection/quantification limits for protein aggregates. Compared to size-exclusion chromatography (SEC), HF5 demonstrated superior selectivity and potential as orthogonal analytical method in the extended characterization assays, often required by therapeutic protein formulations. In addition, the developed HF5 methods have proven to be rapid, highly selective, sensitive and repeatable. HF5 was ideally suitable as first dimension of separation of aging-related protein aggregates from whole cell lysates (proteome pre-fractionation method) and, by HF5-(UV)-MALS online coupling, important biophysical information on the fractionated proteins and protein aggregates was gathered: size (rms radius and hydrodynamic radius), absolute MW and conformation.

Charge transport properties of organic conjugated polymers for photovoltaic applications

Charge transport in conjugated polymers as well as in bulk-heterojunction (BHJ) solar cells made of blends between conjugated polymers, as electron-donors (D), and fullerenes, as electron-acceptors (A), has been investigated. It is shown how charge carrier mobility of a series of anthracene-containing poly(p-phenylene-ethynylene)-alt-poly(p-phenylene-vinylene)s (AnE-PVs) is highly dependent on the lateral chain of the polymers, on a moderate variation of the macromolecular parameters (molecular weight and polydispersity), and on the processing conditions of the films. For the first time, the good ambipolar transport properties of this relevant class of conjugated polymers have been demonstrated, consistent with the high delocalization of both the frontier molecular orbitals. Charge transport is one of the key parameters in the operation of BHJ solar cells and depends both on charge carrier mobility in pristine materials and on the nanoscale morphology of the D/A blend, as proved by the results here reported. A straight correlation between hole mobility in pristine AnE-PVs and the fill factor of the related solar cells has been found. The great impact of charge transport for the performance of BHJ solar cells is clearly demonstrated by the results obtained on BHJ solar cells made of neat-C70, instead of the common soluble fullerene derivatives (PCBM or PC70BM). The investigation of neat-C70 solar cells was motivated by the extremely low cost of non-functionalized fullerenes, compared with that of their soluble derivatives (about one-tenth). For these cells, an improper morphology of the blend leads to a deterioration of charge carrier mobility, which, in turn, increases charge carrier recombination. Thanks to the appropriate choice of the donor component, solar cells made of neat-C70 exhibiting an efficiency of 4.22% have been realized, with an efficiency loss of just 12% with respect to the counterpart made with costly PC70BM.