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Neue nanoporöse Materialien mit niedrigen Dielektrizitätskonstanten werden in der Mikroelektronik dringend benötigt. Eine Methode, die Dielektrizitätskonstante eines gegebenen Materials weiter zu reduzieren, ist die Einführung von geschlossenen und luftgefüllten Poren im Nanometerbereich. Die Porosität wird durch die Verwendung eines Zweikomponentensystems bestehend aus einer stabilen Matrix und einem labilen Porenbildner eingeführt; aus diesen wird ein Blend hergestellt, und durch anschließende Zersetzung des Porenbildners entsteht ein poröses Matrixpolymer mit stabilen Aushöhlungen. Im Vordergrund dieser Arbeit stand die Synthese und Charakterisierung hochverzweigter Polyphenylene über die Diels-Alder-Reaktion von phenylierten Cyclopentadienonen mit phenylierten Alkinen zur Verwendung als Matrixmaterialien in nanoporösen Isolatorsystemen. Dabei wurde sowohl von A2- und B3-Monomeren als auch von AB2- und AB-Monomeren ausgegangen. Die hochverzweigten Polyphenylene sind vielversprechende Materialien mit hervorragenden isolierenden und chemischen Eigenschaften wie hohen thermischen Stabilitäten und guten Löslichkeiten in organischen Lösungsmitteln, was eine wichtige Voraussetzung für die Verwendung der Polymere in der Mikroelektronik darstellt. Die verschiedenen Syntheseansätze erlauben dabei eine Kontrolle über die Endgruppen und die Verzweigung. Daneben wurden thermolabile hochverzweigte Polycarbonate und Polytriazenester als Porenbildner synthetisiert und mit Silylether-Endgruppen modifiziert, wobei mit der tert-Butyldiphenylsilyl-Gruppe die besten Ergebnisse bezüglich der Mischbarkeit mit der Polyphenylenmatrix erhalten wurden. Außerdem wurden Blends in Form von dünnen Schichten aus den hochverzweigten Polyphenylenen mit den Porenbildnern im Hinblick auf die potentielle Anwendung der Materialien als nanoporöse Isolatoren charakterisiert.

In this work, hyperbranched aromatic polyesters-polyphenols based on 4,4-bis(4’ hydroxy¬phenyl)pentanoic acid (BHPPA) were prepared and, according to the authors knowledge, for the first time tested as precursors for polyurethane bulk resins and coatings. Comparison of poly-BHPPA with competing products The materials prepared in this work show better properties than their aliphatic polyester-polyol analoga based on 2,2-bis-(hydroxymethyl)propanoic acid (BHMPA). Especially, the solubility of poly-BHPPA in organic solvents is better and poly-BHPPAs also do not tend to microphase separation during their reaction with isocyanates, in contrast to poly-BHMPAs. The poly-BHPPA and the polyurethane networks made from them display higher Tg values than analogous poly- BHMPA compounds. Because of the high Tg of the reacting and final systems, curing must occur at elevated temperatures (90°C) in order to avoid undercure. The lower reactivity of phenolic OH groups prevents the reaction from being too fast at that temperature. A drawback of the polyurethanes based on the aromatic polyesters-polyols prepared is the lower thermal stability of their urethane bonds, if compared to aliphatic urethanes. An interesting possibility for future investigations would be the modification of the BHPPA monomer in order to change the OH functionality from phenolic to aliphatic OH, e.g. by replacement of the phenolic OH by hydroxymethyl or hydroxyethyl groups (requires a strong modification of the monomer synthesis) or simpler by reacting the phenolic OH of BHPPA with a suitable reagent like oxirane, which would lead to groups like O-CH2-CH2-OH in the place of the phenolic OH. Such a BHPPA modification should in turn yield modified “poly-BHPPA” polycondensates, which would combine the advantages of poly-BHPPA with those of aliphatic OH precursors of polyurethanes. Poly-BHPPA synthesis Hyperbranched polymers of the 4,4-bis-(4’-hydroxyphenyl)pentanoic acid (BHPPA) were synthesized successfully by the catalyzed (by dibutyltin diacetate) polycondensation of BHPPA. The products obtained were oligomers with number average molecular weight ranging from 1800 to 3400 g/mol (polymerization degree of ca. 6 to 12), displaying a first moment of functionality in the range 7 to 14. Such products were good OH precursors for the preparation of polyurethane coatings, because higher functional polymers would gel at low conversions. The analysis of the functional groups (determination of acid and hydroxyl numbers) and the 1H-NMR and the 13C-NMR spectroscopy were found to be good methods for the determination of molecular weights. The polydispersity of the poly-BHPPA products was in the range 3.5 to 6. Their degree of branching was found to be in the range 0.36 to 0.47. Poly-BHPPA containing aliphatic polyols as core monomers were also prepared successfully. Difunctional and trifunctional core monomers usually reached a full conversion of their OH groups, while the tetra- and hexafunctional core monomers were converted only to 89%. In all these products however, a considerable amount, usually even a majority, of the polymer molecules were core free. The poly-BHPPA products prepared displayed relatively high glass transition temperatures, in the range of 84°C to 114°C, obviously due to interactions between the phenol groups and to hydrogen bridging. The thermal stability of these products was also high, with decomposition occurring near 350°C (at a heating rate of 10°C / min) Kinetics investigations of the poly-BHPPA reactivity towards isocyanates The poly-BHPPA are polyphenols and were expectedly found to react significantly slower with isocyanates than aliphatic alcohols. The reactivity of poly BHPPA was also found to be somewhat lower than that of the monofunctional, low molar-mass 4 ethylphenol. Hexamethylene diisocyanate trimer, Desmodur N3300, was found to be more reactive than hexamethylene diisocyanate (HDI) or butyl isocyanate in all experiments, possibly due to a substitution effect. The substitution effect can be explained by a change of microenvironment caused by conversion of isocyanate group and OH group into urethane groups. The reactions of low-molecular-mass alcohols or phenols with low molecular weight isocyanates followed well the 2nd order kinetics, while the reactions of poly-BHPPA with isocyanates show deviations from ideal 2nd order kinetics at higher conversions. All the kinetics experiments were carried out under catalysis by dibutyltin dilaurate. This catalyst inhibits the undesired reaction of isocyanate groups with moisture. It was also found that the catalysis was necessary to reach reasonable curing times for poly-BHPPA based polyurethane networks. The uncatalyzed systems reacted extremely slowly. Preparation of polyurethane networks from poly-BHPPA The poly BHPPA products prepared were used successfully as OH functional precursors of polyurethane networks. The networks prepared contained only very low sol fractions. Acetone and also ethylene diglycol dimethylether (diglyme) were found to be good swelling solvents for the networks prepared, while methyl propyl ketone was a much poorer solvent and aromatic compounds like toluene or xylene practically did not swell the poly BHPPA based polyurethanes. The networks prepared contain a relatively high amount of cyclic bonds, 40 to 50% in the finally cured state, which is an expected result for systems with precursors of high functionality and with small distances between the functional groups. The temperature of glass transition (Tg) of the networks prepared (ranging from 68°C to 126°C) depends of the poly BHPPA precursor used: it increases with increasing molecular mass and with increasing core functionality. The choice of the isocyanate crosslinker also influences Tg: the networks made from HDI show higher Tg values, than networks made from the same poly BHPPA but crosslinked with Desmodur N3300 (Tri HDI). The urethane bonds in the networks prepared start to decompose near 140°C. The easier degradation of PU with aromatic urethane bonds is a disadvantage in comparison with aliphatic polyurethanes, whose decomposition starts at 200°C. The surfaces of polyurethane coatings prepared are smooth, displaying a roughness of ca. 20-25 nm, and relatively hydrophilic: the contact angle with water was found to be near 80°. The prepared networks are also relatively hard, possessing the Shore D hardness of 70.

Synthesis and characterisation of the bis-MPA based branched materials was performed. Thymine derivative was incorporated into the polymer structure as a core moiety and an active centre for H-bonding. The formation of assemblies was investigated. / Im Rammen der Doktorarbeit wurden bis-MPA basierter dendrititsche und hochverzweigte Polymeren synthetisiert. Sie haben Thymin Derivat als Kernmolecule. Die H-Brücken zwischen Polymeren und DAPy Derivate wurden untersucht.

Dendritische Polymere werden im zunehmenden Maße als nicht-virale Vektoren für virus- oder tumor-assoziierte Antigen-Peptide zur Entwicklung neuer immuntherapeutischer Strategien eingesetzt. Diese beruhen auf der Verwendung von dendritischen Zellen (DCs), welche Schlüsselzellen bei der Induktion und Aufrechterhaltung einer T-Zell-basierten Immunantwort darstellen. Im Rahmen dieser Arbeit wurden Nitrilotriessigsäure-funktionalisierte dendritische Glycopolymere (NTA-DG) für den Transport von Antigen-Peptiden in DCs etabliert. Die Ni(II)-NTA-DGs waren durch definierte Komplexierungs- und Freisetzungseigenschaften charakterisiert. So wurde das Antigen-Peptid bei einem pH-Wert unter 6 vom polymeren Träger freigesetzt. Die gebildeten Polyplexe, zwischen Ni(II)-NTA-DG und dem Antigen-Peptid, bewirkten eine Erhöhung der Antigen-Peptid-Aufnahme in immaturen DCs (iDCs). Dieses war nach der Endozytose im frühen endosomalen und lysosomalen Kompartiment von iDCs lokalisiert. Somit kann das Antigen-Peptid am MHC Klasse II-Molekül im lysosomalen Kompartiment ohne sterische Hinderungen durch die Polymeroberfläche binden. Die Polyplexe bewirkten eine Aktivierung der iDCs durch Aufregulation der kostimulatorischen Moleküle CD86 und CD80 sowie der pro-inflammatorischen Zytokine IL-6 und IL-8. Weiterhin wurde die Migrationsfähigkeit und das pro-inflammatorische Potential der Antigen-Peptid enthaltenen maturen DCs (mDCs) aufrechterhalten. Somit stellen Ni(II)-NTA-DGs ein vielversprechendes polymeres Trägersystem für Antigen-Peptide dar.

Hyperbranched poly(ethylene imine) with Mw 5,000 and 25,000 Da and different degrees of substitution with maltose (PEI-Mal) was firstly described by Appelhans et al. Its biocompatibility and the potential to complex anionic molecules was demonstrated previously. In this study, the characterisation of host-guest interactions of PEI-Mal with various anionic water-soluble guest molecules with aromatic moieties in the structure (adenosine triphosphate, rose bengal, and acid red 26) in solution was provided. Also, a multicomponent drug@PEI-Mal@hydrogel system was achieved.

Dendrimers are a class of perfectly branched symmetric monodisperse macromolecules, which are synthesized using a stepwise procedure. Due to their highly symmetric structure, they possess a definite core, discrete generations and a large number of terminal units. The large number of terminal units and its compact globular conformation endow this class of macromolecules with several unique properties. Over the past two decades, a number of researchers have synthesized a variety of dendrimers and explored their potential applications in various fields ranging from drug delivery, energy harvesting to catalysis. However, dendrimers require tedious stepwise synthesis and purification which limits their scalability. Hyperbranched polymers (HBPs) are a related class of macromolecules having similar highly branched structure but with large number of linear defects and, therefore, they may be considered as unsymmetrical analogues of dendrimers. Despite of having a large number of defects, HBPs display majority of the properties which dendrimers possess such as, high solubility, low chain entanglement, low solution and melt viscosity, encapsulation of guest molecules, conformational adaptability etc. The origin of these defects lies in the single-step statistical random growth process. Although, hyperbranched polymers possess a randomly branched structure, they also carry a large number of peripheral units, like dendrimers. Since, hyperbranched polymers are prepared in a single step, they can be readily scaled up which make them commercially attractive. One of the most widely used methods to prepare hyperbranched polymers is by polycondensation of a AB2 monomer. In our laboratory, during past decade a novel melt trans-etherification methodology was developed to prepare hyperbranched polyethers. For this method, a AB2 monomer was designed having two methoxy benzyl units and one aliphatic hydroxyl group, which in presence of a mild organic acid at 150°C undergoes melt polymerization under continuous removal of methanol. Although, this method allows one to prepare a variety of high molecular weight hyperbranched polyethers structures, it suffers from one serious limitation associated with the monomer structure; the aromatic ring in the monomer should be either electronically deactivated or per-substituted to preclude a side reaction due to electrophilic aromatic substitution, which could result in the formation of insoluble cross-linked product. Polyacetals are a class of polymers which readily degrades under mildly acidic conditions. One of the primary objectives of this thesis was to develop a simple strategy to prepare hyperbranched polyacetal, which would be a new class of highly branched acid-labile scaffold. To achieve this, we used a relatively under-explored chemistry based on trans¬acetalization. Solvent-free melt polymerization via trans-acetalization exhibited some advantages over the trans-esterification or trans-etherification processes; for instance, it required substantially low temperatures, afforded faster reaction rates and absence of side reactions that could lead to crosslinked products. In the 2nd chapter, the first synthesis of hyperbranched polyacetals via this novel melt trans-acetalization polymerization process has been described. The process proceeds via the self-condensation of an AB2 type monomer carrying a hydroxyl group and a dimethylacetal unit (see Figure 1); the continuous removal of low boiling methanol drives the equilibrium towards polymer formation. Here, since the incipient carbocation is stabilized by a neighbouring oxygen atom, it has a substantially lower reactivity and hence does not take part in the electrophilic aromatic substitution; therefore, per-alkylation of the monomer was not required to prevent crosslinking, unlike in the case of the melt trans-etherification process developed earlier. Figure1. Synthesis of hyperbranched polyacetals via trans-acetalization polymerization; different types of units, namely dendtritic (D), linear (L) and terminal (T) units are shown. We studied the degradation behaviour of the solid polymer in an aqueous buffer solution having a pH of 4. Due to the susceptibility of the acetal linkages to hydrolysis, the polymer degrades readily under these mildly acidic conditions to yield 4-hydroxymethyl benzaldehyde as the primary product. After observing the fast degradation kinetics of the hyperbranched polyacetal, we developed approaches to control the rate of degradation. Interestingly, because of the unique topology of hyperbranched structures, the rate of polymer degradation was readily tuned by changing just the nature monomer; longer chain dialkylacetals, such as dibutyl- and dihexylacetals based monomers yielded hyperbranched polymers bearing longer alkyl groups at their molecular periphery. The highly branched topology and the relatively high volume-fraction of the terminal alkyl groups resulted in a significant lowering of the ingress rates of the aqueous reagents to the loci of degradation and, consequently, the degradation rates of the polymers were dramatically influenced by the hydrophobic nature of the terminal alkyl substituents. In an effort to understand this, we performed the degradation studies in solution state, where all three polymers showed almost same rate of degradation. The simple synthesis and easy tuneability of the degradation rates make these materials fairly attractive candidates for use as degradable scaffolds. As already mentioned, the main difference between dendrimers and hyperbranched polymers is that HBPs carry a large number of statistically distributed linear defects. The origin of these linear segments is single step statistically random growth process. There are three kinds of linkages present in the HB structure. For a HB polymer generated from condensation polymerization of an AB2 monomer, these three kinds of linkages are: (i) the linkages where both the B groups have reacted is called a dendritic (D) unit, (ii) linkages where one of the B group has reacted is called a linear (L) unit, and (iii) linkages where both the B groups remain unreacted is called a terminal (T) unit. The defect levels in hyperbranched polymers is quantified by a parameter called degree of branching (DB), which is mole-fraction of dendritic and terminal units with respect to all types of repeat units. In a typical single step AB2 polycondensation process the DB value usually is around 0.5. The strategy most commonly used to achieve high DB values, specifically while using AB2 type self-condensations, is to design an AB2 monomer wherein the reaction of the first B-group leads to an enhancement of the reactivity of the second one. In the 3rd chapter the challenge of synthesizing defect-free hyperbranched polythioacetal has been addressed. In this study, it was shown that an AB2 monomer carrying a dimethylacetal unit and a benzyl thiol group undergoes a rapid self-condensation in the melt under acid-catalysis to yield a hyperbranched polydithioacetal (Figure 2a). By analyzing 1H, 13C, hetero-correlation NMR spectra and by comparison of the NMR spectrum of the polymer with those of model compounds, it was established that the HB polydithioacetals do not contain any linear defects. Furthermore, to understand the origin of defect-free structure, model reactions between dimethylacetal of tolualdehyde and benzyl mercaptan (Figure 2b) were carried out. NMR studies using of these model reactions reveal that the intermediate monothioacetal is relatively unstable under the polymerization conditions and transforms rapidly to the dithioacetal (Figure 2c); since this second step occurs irreversibly towards polymer formation, it leads to a defect-free hyperbranched dithioacetal. Isothermal TGA analysis proved to be an effective tool for monitoring the kinetics of the melt polymerization; these studies revealed that the formation of the polydithioacetal is significantly faster than previously studied polyacetal polymerization, and in the former case two distinct kinetic steps are clearly evident. Figure 2. (a) Synthesis of defect-free hyperbranched polythioacetal; chemical structure of monomer and hyperbranched polydithioacetal; (b) model reaction to probe the unstable intermediate, and (c) variation of the concentration of different species during the model reaction as a function of time showing the appearance and disappearance of unstable intermediate. One of the major differences between linear and hyperbranched polymers is the availability of large number of accessible terminal groups in the latter. Several properties of the hyperbranched polymers are known to be influenced by the nature of the peripheral groups. Of the many methods that have been designed to functionalize the periphery of HBPs, AB2 + A type copolymerization is one of the most readily implementable. Figure 3. (a) Peripheral modification of hyperbranched polydithioacetal using trans-thiocetalization; (b) schematic representation of the sulphur rich hyperbranched polythioacetal having C-22 alkyl chains on its periphery and (c) TEM images of gold nanoparticle synthesized and stabilized via C-22 functionalized hyperbranched polythioacetal. In chapter 3, the synthesis of a defect-free hypebranched polymer via trans-thiocetalization method was described; these polymers possessed only two kinds of units, namely terminal dimethylacetal groups and dendritic dithioacetal units. Because of the difference in reactivity between the dendritic (D) and terminal (T) units, the terminal groups alone was completely transformed, under acid-catalyzed conditions, to a dithioacetal unit by reaction with a variety of thiols, (Figure 3a) such as dodecanethiol, benzyl mercaptan, ethyl, 3-mercaptopropionate etc.; this transformation of the periphery was shown to be quantitative. One unique feature of this hyperbranched polydithioacetal is the high sulfur content; in order to exploit this aspect, the periphery was selectively transformed with docosyl (C-22) segments, and these sulfur-rich hydrophobically capped hyperscaffolds were utilized to stabilize gold nanoparticles in non-polar solvents (Figure 3b and 3c.) The Au-NPs, thus prepared, were characterized by UV-Visible spectroscopy and transmission electron microscopy; it was shown that, typically particles of about 4-5 nm were produced and they could be dried and readily re-dispersed in organic solvents. In the final chapter of the thesis, the first synthesis of photodegradable hyperbranched polyacetals via a melt trans-acetalization polymerization method is described. The AB2 monomer was designed to carry a dimethyl acetal unit, and a nitro group placed ortho to a hydroxymethyl group (Figure 4a). Self-condensation of this AB2 monomer under melt polymerization conditions gives rise to a hyperbranched polyacetal wherein each repeat unit contains a 2-nitrobenzyl linkage which is susceptible to photolytic degradation upon exposure to 365 nm light. Figure 4. (a) Synthesis of photodegradable hyperbranched nitro polyacetal; (b) scanning electron micrograph of the positive pattern obtained from hyperbranched nitro-polyacetal; (c) synthesis of alkyne-azide clickable hyperbranched nitro polyacetal; and (d) clicking onto the reactive micropatterns. Irradiation with UV light causes the photodegradation of the polymer leading to the formation of 2-nitroso terephthalaldehyde and other low molecular weight oligomeric species. Exploiting this photodegradability, the use of this HBP as a positive photoresist to generate micron-size patterns has been demonstrated (Figure 4b); furthermore, changing the terminal groups from dimethyl acetal to dipropargyl acetal (Figure 4c), permitted the generation of patterned substrates that can be clicked with any desired functionality using the azide-yne click reaction. This last feature is unprecedented and provides a potentially quick handle to create functionalizable patterned surfaces.

Ce travail était centré sur les propriétés thermodynamiques et mécaniques des polymères denses et sur leurs liens avec les systèmes de la matière molle et l'étude des propriétés de conformation et les propriétés rhéologiques des polymères hyperbranchés. L'étude de polymères hyperbranchés montre qu'ils sont substantiellement différents de leurs analogues linéaires. En utilisant des méthodes de simulation, nous pouvons obtenir des informations inaccessibles par des méthodes expérimentales et heureusement obtenir de précieuses informations du point de vue industriel et scientifique. Cette étude traite le problème par des simulations et comme expliqué dans le manuscrit, nous avons observé un centre de faible densité pour un grand nombre de générations et une enveloppe extérieure plutôt compacte. Cette tendance se retrouve également pour les propriétés dynamiques. Le manque d’enchevêtrement dans les polymères hyperbranchés fait d'eux des matériaux moins résistant que ceux composés de chaînes linéraires. La viscosité perd sa simple dépendance à la masse dans le cas d'une chaîne linéaire. / This study is focused on thermodynamic and mechanical properties of dense polymers solutions and related soft matter systems and conformational and rheological properties of hyperbranched polymers. Studies of hyperbranched polymers shows that they are substantially different from their linear analogs. By using simulation methods we could reach the information not available by experimental methods and hopefully obtain valuable information from both industrial and scientific points of view.This study is treating this problem by means of computer simulations where as a result we can see a hollow center for high generation numbers and a rather compact outer shell. This tendency expands to dynamical behavior. Lack of chain entanglements in hyperbranched polymers make them not very tough materials in a comparison with linear chains. Another point is a decrease of mobility caused by large amount of branch points. Viscosity loses its simple dependence on the mass as for the case of linear chains.

The textile industry is a big environmental polluter, with one of the biggest concerns being water pollution and usage. This necessitates resource efficient methods for wet textile processes. To reduce the resources used during wet textile processing, a novel technology was researched in this thesis to dye and hydrophobic finish wool in a one-step process. Two different wool fabrics were exhaust dyed and pad finished as a conventional method to compare to dyeing and finishing in a two-step and one-step process with a hydraulic spray atomising system. In all three processes, acid and reactive dyes were used for dyeing and hyperbranched polymers, i.e. dendrimers, were used for hydrophobic finishing. To test the colour and hydrophobicity fastness, washing and abrasion tests were done on the samples of all three processes. It was found that there is a big colour difference between the conventional and hydraulic spray method, where the colour is less strong in the hydraulic spray method. This has to do with the difference in the dye fixation step, where in the conventional method, the dye fixation happens in an aqueous medium, and in the hydraulic spray this happens in a nonaqueous medium. The hydrophobicity is however significantly better in the samples finished in the hydraulic spray, as this is rather a surface treatment. The results in colour and contact angle between the two-step and one-step process did not significantly change, so it can be concluded that it is possible to combine dyeing and finishing in the hydraulic spray method. The colour and hydrophobic fastness to abrasion and washing is significantly worse for the samples of the hydraulic spray method compared to the conventional method. The hydraulic spray method can still be optimised to overcome problems with colour and fastness, however this is future work. The hydraulic spray method uses significantly less water, chemicals and energy in a two-step process, and even more in a one-step process. Therefore, it has the potential to reduce the use of water, chemicals and energy in wet textile processing, for all types of fibres, and thus strongly contribute to a more environmental conscious wet textile process.