@misc{Metzke2013,
  type      = {Master Thesis},
  author    = {Metzke, Sarah},
  title     = {Synthesis and characterization of transition metal nitrides and carbides for catalysis and electrochemistry application},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-69835},
  school      = {Universit{\"a}t Potsdam},
  year      = {2013},
  abstract  = {It was the goal of this work to explore two different synthesis pathways using green chemistry. The first part of this thesis is focusing on the use of the urea-glass route towards single phase manganese nitride and manganese nitride/oxide nano-composites embedded in carbon, while the second part of the thesis is focusing on the use of the "saccharide route" (namely cellulose, sucrose, glucose and lignin) towards metal (Ni0), metal alloy (Pd0.9Ni0.1, Pd0.5Ni0.5, Fe0.5Ni0.5, Cu0.5Ni0.5 and W0.15Ni0.85) and ternary carbide (Mn0.75Fe2.25C) nanoparticles embedded in carbon. In the interest of battery application, MnN0.43 nanoparticles surrounded by a graphitic shell and embedded in carbon with a high surface area (79 m^2/g) were synthesized, following a previously set route.The comparison of the material characteristics before and after the discharge showed no remarkable difference in terms of composition and just slight differences in the morphological point of view, meaning the particles are stable but agglomerate. The graphitic shell is contributing to the resistance of the material and leads to a fine cyclic stability over 140 cycles of 230 mAh/g after the first charge/discharge and coulombic efficiencies close to 100\%. Due to the low voltage towards Li/Li+ and the low polarization, it might be an attractive anode material for lithium ion batteries. However, the capacity is still noticeably lower than the theoretical value for MnN0.43. A mixture of MnN0.43 and MnO nanoparticles embedded in carbon (surface area 93 m^2/g) was able to improve the cyclic stability to over 160 cycles giving a capacity of 811 mAh/g, which is considerably higher than the capacity of the conventional material graphite (372 mAh/g). This nano-composite seems to agglomerate less during the process of discharge. Interestingly, although the capacity is much higher than of the single phase manganese nitride, the nano-composite seems to only contain MnN0.43 nanoparticles after the process of discharge with no oxide phase to be found. Concerning catalysis application, different metal, metal alloy, and metal carbide nanoparticles were synthesized using the saccharide route. At first, systems that were already investigated before, being Pd0.9Ni0.1, Pd0.5Ni0.5, Fe0.5Ni0.5 and Mn0.75Fe2.25C using cellulose as the carbon source were prepared and tested in an alkylation reaction of toluene with benzylchloride. Unexpectedly, the metal alloys did not show any catalytic activity, but the ternary carbide Mn0.75Fe2.25C showed fine catalytic activity of 98\% conversion after 9 hour reaction time (110 °C). In a second step, the saccharide route was modified towards other carbon sources and carbon to metal ratios in order to improve the homogeneity of the samples and accessibility of the particle surfaces. The used carbon sources sucrose and glucose are similar in their basic structure of carbohydrates, but reducing the (polymeric) chain length. Indeed, the cellulose could be successfully replaced by sucrose and glucose. A lower carbon to metal ratio was found to influence the size, homogeneity and accessibility (as evidenced by TEM) of the samples. Since sucrose is an aliment, glucose is the better choice as a carbon source. Using glucose, the synthesis of Cu0.5Ni0.5 and W0.15Ni0.85 nano-composites was also possible, although the later was never obtained as pure phase. These alloy nano-composites were tested, along with nickel0 nanoparticles also prepared with glucose and on their catalytic activity towards the reduction of phenylacetylene. The results obtained let believe that any (poly) saccharide, including lignin, could be used as carbon source. The nickel0 nano-composites prepared with lignin as a carbon source were tested along with those prepared with cellulose and sucrose for their catalytic activity in the transfer hydrogenation of nitrobenzene (results compared with exposed nickel nanoparticles and nickel supported on carbon) leading to very promising results. Based on the urea-glass route and the saccharide route, simple equipment and transition metals, it was possible to have a one-pot synthesize with scale-up possibilities towards new material that can be applied in catalysis and battery systems.},
  language  = {en}
}
@phdthesis{Suetterlin2013,
  author    = {S{\"u}tterlin, Martin},
  title     = {New inverse hydogel opals as protein responsive sensors},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-70179},
  school      = {Universit{\"a}t Potsdam},
  year      = {2013},
  abstract  = {In this work, the development of temperature- and protein-responsive sensor materials based on biocompatible, inverse hydrogel opals (IHOs) is presented. With these materials, large biomolecules can be specifically recognised and the binding event visualised. The preparation of the IHOs was performed with a template process, for which monodisperse silica particles were vertically deposited onto glass slides as the first step. The obtained colloidal crystals with a thickness of 5 μm displayed opalescent reflections because of the uniform alignment of the colloids. As a second step, the template was embedded in a matrix consisting of biocompatible, thermoresponsive hydrogels. The comonomers were selected from the family of oligo(ethylene glycol)methacrylates. The monomer solution was injected into a polymerisation mould, which contained the colloidal crystals as a template. The space in-between the template particles was filled with the monomer solution and the hydrogel was cured via UV-polymerisation. The particles were chemically etched, which resulted in a porous inner structure. The uniform alignment of the pores and therefore the opalescent reflection were maintained, so these system were denoted as inverse hydrogel opals. A pore diameter of several hundred nanometres as well as interconnections between the pores should facilitate a diffusion of bigger (bio)molecules, which was always a challenge in the presented systems until now. The copolymer composition was chosen to result in a hydrogel collapse over 35 °C. All hydrogels showed pronounced swelling in water below the critical temperature. The incorporation of a reactive monomer with hydroxyl groups ensured a potential coupling group for the introduction of recognition units for analytes, e.g. proteins. As a test system, biotin as a recognition unit for avidin was coupled to the IHO via polymer-analogous Steglich esterification. The amount of accessible biotin was quantified with a colorimetric binding assay. When avidin was added to the biotinylated IHO, the wavelength of the opalescent reflection was significantly shifted and therefore the binding event was visualised. This effect is based on the change in swelling behaviour of the hydrogel after binding of the hydrophilic avidin, which is amplified by the thermoresponsive nature of the hydrogel. A swelling or shrinking of the pores induces a change in distance of the crystal planes, which are responsible for the colour of the reflection. With these findings, the possibility of creating sensor materials or additional biomolecules in the size range of avidin is given.},
  language  = {en}
}
@phdthesis{Salffner2013,
  author    = {Salffner, Katharina},
  title     = {Entwicklung eines breitbandigen Cavity-Ring-Down-Spektrometers unter Verwendung nahinfraroter, inkoh{\"a}renter Strahlung},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-68952},
  school      = {Universit{\"a}t Potsdam},
  year      = {2013},
  abstract  = {In der vorliegenden Arbeit werden verschiedene Spektrometer f{\"u}r die Analyse von Gasen bzw. Gasgemischen vorgestellt und deren Design, Aufbau, Charakterisierung und Optimierung beschrieben. Das Resultat der Optimierung und Weiterentwicklungen ist ein spektral breitbandiges Cavity-Ring-Down-Spektrometer (CRD-Spektrometer). Ausgangspunkt der hier vorgestellten Arbeit ist ein Spektrometer auf Basis klassischer Absorptionsspektroskopie in einer Multireflexionszelle. F{\"u}r dieses Spektrometer wurde als Strahlquelle ein Superkontinuumlaser verwendet. Der Vorteil dieses Spektrometers liegt in seiner Kompaktheit. Mit diesem Spektrometer wurden Absorptionsspektren von mehreren Reingasen und einem Gasgemisch {\"u}ber einen Wellenl{\"a}ngenbereich von 1500 nm - 1700 nm aufgenommen. Der qualitative Vergleich mit zu erwartenden Spektren, welche auf der HITRAN-Datenbank basieren, zeigte eine gute {\"U}bereinstimmung. Die quantitative Interpretierbarkeit der Daten war jedoch stark eingeschr{\"a}nkt aufgrund des hohen zuf{\"a}lligen und systematischen Fehlers der Messungen. Als Konsequenz aus der als nicht zufriedenstellend bewerteten quantitativen Interpretierbarkeit der Daten wurde eine alternative Messmethode gesucht, welche eine h{\"o}here Sensitivit{\"a}t und Genauigkeit erm{\"o}glicht. Die Wahl fiel auf die Cavity-Ring-Down-Spektroskopie, eine resonatorgest{\"u}tzte Variante der Absorptionsspektroskopie. Wesentliche Vorteile dieser Technik sind a) die Unabh{\"a}ngigkeit von Leistungsschwankungen der Strahlquelle, b) ein effektiver Absorptionsweg von bis zu mehreren Kilometern, welcher sich unmittelbar auf die Sensitivit{\"a}t der Messungen auswirkt, c) die Ermittlung absoluter Absorberkonzentrationen, ohne die Notwendigkeit einer Kalibrierung oder den Vergleich mit einer Referenzzelle und d) die Vernachl{\"a}ssigbarkeit von Absorptionen außerhalb des Resonators. Als notwendiger Zwischenschritt auf dem Weg zu einem breitbandigen CRD-Spektrometer wurde zun{\"a}chst ein monochromatisches CRD-Spektrometer designt, aufgebaut und charakterisiert. F{\"u}r die effektive Einkopplung von Strahlungsenergie in einen Resonator ist die Anpassung der Strahlparameter an die Mode des Resonators notwendig. Voraussetzung dieser Anpassung ist die Kenntnis der Strahlparameter, welche experimentell ermittelt wurden. Im Laufe des Aufbaus des Spektrometers ergab sich, dass trotz der Modenanpassung die Einkopplung der Strahlungsenergie in den Resonator gest{\"o}rt wurde. Daraufhin wurden systematisch m{\"o}gliche Ursachen dieser St{\"o}rung untersucht und das Spektrometer optimiert. Mit diesem optimierten Spektrometer wurden Spektren gemessen, welche sowohl qualitativ als auch quantitativ gut mit den zu erwartenden Spektren {\"u}bereinstimmen. Als Nachweisgrenze dieses Spektrometers wurde ein Wert f{\"u}r den Absorptionskoeffizienten alpha von 10^-8 cm-1 bestimmt. Mit dem monochromatischen CRD-Spektrometer war es zudem m{\"o}glich, isotopenspezifische Messungen durchzuf{\"u}hren. F{\"u}r das breitbandige Spektrometer wurde als Strahlquelle eine ASE-Diode (amplified spontaneous emission) verwendet. Dabei handelt es sich um eine inkoh{\"a}rente Strahlquelle. Mittels Messungen nach dem Prinzip der Cavity-Enhanced-Absorptionsspektroskopie wurde die generelle Funktionalit{\"a}t des resonatorgest{\"u}tzten Spektrometers {\"u}berpr{\"u}ft. Anschließend wurden die wellenl{\"a}ngenabh{\"a}ngigen Abklingsignale des leeren und des mit einem CO2-Luft-Gemisch gef{\"u}llten Resonators gemessen und ebenfalls mit den zu erwartenden Spektren verglichen. Qualitativ stimmen die experimentellen Spektren gut mit den zu erwartenden Spektren {\"u}berein. F{\"u}r die quantitative Interpretation der Daten wurde ein spezieller Algorithmus entwickelt, der die spektrale Aufl{\"o}sung des Systems ber{\"u}cksichtigt. Mit dem vorgestellten Spektrometer ist so die qualitative und quantitative Interpretation der Spektren m{\"o}glich. Die Nachweisgrenze des breitbandigen Cavity-Ring-Down-Spektrometers wurde zu einem Wert von alpha = 8x10^-7 cm-1 bestimmt. Der systematischen und der zuf{\"a}llige Fehler der Messungen lagen bei Werten von ca. 1\%. Bei diesem Spektrometer handelt es sich um einen Prototyp. Mittels Optimierung des Systems lassen sich sowohl der Wert der Nachweisgrenze als auch die Fehler der Messungen verbessern.},
  language  = {de}
}
@phdthesis{Glatzel2013,
  author    = {Glatzel, Stefan},
  title     = {Cellulose based transition metal nano-composites : structuring and development},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-64678},
  school      = {Universit{\"a}t Potsdam},
  year      = {2013},
  abstract  = {Cellulose is the most abundant biopolymer on earth. In this work it has been used, in various forms ranging from wood to fully processed laboratory grade microcrystalline cellulose, to synthesise a variety of metal and metal carbide nanoparticles and to establish structuring and patterning methodologies that produce highly functional nano-hybrids. To achieve this, the mechanisms governing the catalytic processes that bring about graphitised carbons in the presence of iron have been investigated. It was found that, when infusing cellulose with an aqueous iron salt solution and heating this mixture under inert atmosphere to 640 °C and above, a liquid eutectic mixture of iron and carbon with an atom ratio of approximately 1:1 forms. The eutectic droplets were monitored with in-situ TEM at the reaction temperature where they could be seen dissolving amorphous carbon and leaving behind a trail of graphitised carbon sheets and subsequently iron carbide nanoparticles. These transformations turned ordinary cellulose into a conductive and porous matrix that is well suited for catalytic applications. Despite these significant changes on the nanometre scale the shape of the matrix as a whole was retained with remarkable precision. This was exemplified by folding a sheet of cellulose paper into origami cranes and converting them via the temperature treatment in to magnetic facsimiles of those cranes. The study showed that the catalytic mechanisms derived from controlled systems and described in the literature can be transferred to synthetic concepts beyond the lab without loss of generality. Once the processes determining the transformation of cellulose into functional materials were understood, the concept could be extended to other metals and metal-combinations. Firstly, the procedure was utilised to produce different ternary iron carbides in the form of MxFeyC (M = W, Mn). None of those ternary carbides have thus far been produced in a nanoparticle form. The next part of this work encompassed combinations of iron with cobalt, nickel, palladium and copper. All of those metals were also probed alone in combination with cellulose. This produced elemental metal and metal alloy particles of low polydispersity and high stability. Both features are something that is typically not associated with high temperature syntheses and enables to connect the good size control with a scalable process. Each of the probed reactions resulted in phase pure, single crystalline, stable materials. After showing that cellulose is a good stabilising and separating agent for all the investigated types of nanoparticles, the focus of the work at hand is shifted towards probing the limits of the structuring and pattering capabilities of cellulose. Moreover possible post-processing techniques to further broaden the applicability of the materials are evaluated. This showed that, by choosing an appropriate paper, products ranging from stiff, self-sustaining monoliths to ultra-thin and very flexible cloths can be obtained after high temperature treatment. Furthermore cellulose has been demonstrated to be a very good substrate for many structuring and patterning techniques from origami folding to ink-jet printing. The thereby resulting products have been employed as electrodes, which was exemplified by electrodepositing copper onto them. Via ink-jet printing they have additionally been patterned and the resulting electrodes have also been post functionalised by electro-deposition of copper onto the graphitised (printed) parts of the samples. Lastly in a preliminary test the possibility of printing several metals simultaneously and thereby producing finely tuneable gradients from one metal to another have successfully been made. Starting from these concepts future experiments were outlined. The last chapter of this thesis concerned itself with alternative synthesis methods of the iron-carbon composite, thereby testing the robustness of the devolved reactions. By performing the synthesis with partly dissolved scrap metal and pieces of raw, dry wood, some progress for further use of the general synthesis technique were made. For example by using wood instead of processed cellulose all the established shaping techniques available for wooden objects, such as CNC milling or 3D prototyping, become accessible for the synthesis path. Also by using wood its intrinsic well defined porosity and the fact that large monoliths are obtained help expanding the prospect of using the composite. It was also demonstrated in this chapter that the resulting material can be applied for the environmentally important issue of waste water cleansing. Additionally to being made from renewable resources and by a cheap and easy one-pot synthesis, the material is recyclable, since the pollutants can be recovered by washing with ethanol. Most importantly this chapter covered experiments where the reaction was performed in a crude, home-built glass vessel, fuelled - with the help of a Fresnel lens - only by direct concentrated sunlight irradiation. This concept carries the thus far presented synthetic procedures from being common laboratory syntheses to a real world application. Based on cellulose, transition metals and simple equipment, this work enabled the easy one-pot synthesis of nano-ceramic and metal nanoparticle composites otherwise not readily accessible. Furthermore were structuring and patterning techniques and synthesis routes involving only renewable resources and environmentally benign procedures established here. Thereby it has laid the foundation for a multitude of applications and pointed towards several future projects reaching from fundamental research, to application focussed research and even and industry relevant engineering project was envisioned.},
  language  = {en}
}
@phdthesis{Lemke2013,
  author    = {Lemke, Karina},
  title     = {Abtrennung und Charakterisierung von Polyelektrolyt-modifizierten Nanopartikeln},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-68133},
  school      = {Universit{\"a}t Potsdam},
  year      = {2013},
  abstract  = {Gegenstand der Dissertation ist die gr{\"o}ßen- und eigenschaftsoptimierte Synthese und Charakterisierung von anorganischen Nanopartikeln in einer geeigneten Polyelektrolytmodifizierten Mikroemulsion. Das Hauptziel bildet dabei die Auswahl einer geeigneten Mikroemulsion, zur Synthese von kleinen, stabilen, reproduzierbaren Nanopartikeln mit besonderen Eigenschaften. Die vorliegende Arbeit wurde in zwei Haupteile gegliedert. Der erste Teil befasst sich mit der Einmischung von unterschiedlichen Polykationen (lineares Poly (diallyldimethylammoniumchlorid) (PDADMAC) und verzweigtes Poly (ethylenimin) (PEI)) in verschiedene, auf unterschiedlichen Tensiden (CTAB - kationisch, SDS - anionisch, SB - zwitterionisch) basierenden, Mikroemulsionssysteme. Dabei zeigt sich, dass das Einmischen der Polykationen in die Wassertr{\"o}pfchen der Wasser-in-{\"O}l (W/O) Mikroemulsion prinzipiell m{\"o}glich ist. Der Einfluss der verschiedenen Polykationen auf das Phasenverhalten der W/O Mikroemulsion ist jedoch sehr unterschiedlich. In Gegenwart des kationischen Tensids f{\"u}hren die repulsiven Wechselwirkungen mit den Polykationen zu einer Destabilisierung des Systems, w{\"a}hrend die ausgepr{\"a}gten Wechselwirkungen mit dem anionischen Tensid in einer deutlichen Stabilisierung des Systems resultieren. F{\"u}r das zwitterionische Tensid f{\"u}hren die moderaten Wechselwirkungen mit den Polykationen zu einer partiellen Stabilisierung. Der zweite Teil der Arbeit besch{\"a}ftigt sich mit dem Einsatz der unterschiedlichen, Polyelektrolyt- modifizierten Mikroemulsionen als Templatphase f{\"u}r die Herstellung verschiedener, anorganischer Nanopartikel. Die CTAB-basierte Mikroemulsion erweist sich dabei als ungeeignet f{\"u}r die Herstellung von CdS Nanopartikeln, da zum einen nur eine geringe Toleranz gegen{\"u}ber den Reaktanden vorhanden ist (Destabilisierungseffekt) und zum anderen das Partikelwachstum durch den Polyelektrolyt-Tensid-Film nicht ausreichend begrenzt wird. Zudem zeigt sich, dass eine Abtrennung der Partikel aus der Mikroemulsion nicht m{\"o}glich ist. Die SDS-basierten Mikroemulsionen, erweisen sich als geeignete Templatphase zur Synthese kleiner anorganischer Nanopartikel (3 - 20 nm). Sowohl CdS Quantum Dots, als auch Gold Nanopartikel konnten erfolgreich in der Mikroemulsion synthetisiert werden, wobei das verzweigte PEI einen interessanten Templat-Effekt in der Mikroemulsion hervorruft. Als deutlicher Nachteil der SDS-basierten Mikroemulsionen offenbaren sich die starken Wechselwirkungen zwischen dem Tensid und den Polyelektrolyten w{\"a}hrend der Aufarbeitung der Nanopartikel aus der Mikroemulsion. Dabei erweist sich die Polyelektrolyt-Tensid-Komplexbildung als hinderlich f{\"u}r die Redispergierung der CdS Quantum Dots in Wasser, so dass Partikelaggregation einsetzt. Die SB-basierten Mikroemulsionen erweisen sich als g{\"u}nstige Templatphase f{\"u}r die Bildung von gr{\"o}ßen- und eigenschaftenoptimierten Nanopartikeln (< 4 nm), wobei insbesondere eine Modifizierung mit PEI als ideal betrachtet werden kann. In Gegenwart des verzweigten PEI gelang es erstmals ultrakleine, fluoreszierende Gold Cluster (< 2 nm) in einer SB-basierten Mikroemulsion als Templatphase herzustellen. Als besonderer Vorteil der SB-basierten Mikroemulsion zeigen sich die moderaten Wechselwirkungen zwischen dem zwitterionischen Tensid und den Polyelektrolyten, welche eine anschließende Abtrennung der Partikel aus der Mikroemulsion unter Erhalt der Gr{\"o}ße und ihrer optischen Eigenschaften erm{\"o}glichen. In der redispergierten w{\"a}ssrigen L{\"o}sung gelang somit eine Auftrennung der PEI-modifizierten Partikel mit Hilfe der asymmetrischer Fluss Feldflussfraktionierung (aF FFF). Die gebildeten Nanopartikel zeigen interessante optische Eigenschaften und k{\"o}nnen zum Beispiel erfolgreich zur Modifizierung von Biosensoren eingesetzt werden.},
  language  = {de}
}
@phdthesis{Winkler2013,
  author    = {Winkler, Henning},
  title     = {Synthese von thermoplastisch verarbeitbaren Fetts{\"a}ure-Acylderivaten der St{\"a}rke und Proteine},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-71089},
  school      = {Universit{\"a}t Potsdam},
  year      = {2013},
  abstract  = {In den vergangenen Jahren wurden stetig wachsende Produktionskapazit{\"a}ten von Biokunststoffen aus nachwachsenden Rohstoffe nverzeichnet. Trotz großer Produktionskapazit{\"a}ten und einem geeigneten Eigenschaftsprofil findet St{\"a}rke nur als hydrophile, mit Weichmachern verarbeitete thermoplastische St{\"a}rke (TPS) in Form von Blends mit z. B. Polyestern Anwendung. Gleiches gilt f{\"u}r Kunststoffe auf Proteinbasis. Die vorliegende Arbeit hat die Entwicklung von Biokunststoffen auf St{\"a}rkebasis zum Ziel, welche ohne externe Weichmacher thermoplastisch verarbeitbar und hydrophob sind sowie ein mechanisches Eigenschaftsprofil aufweisen, welches ein Potenzial zur Herstellung von Materialien f{\"u}r eine Anwendung als Verpackungsmittel bietet. Um die Rohstoffbasis f{\"u}r Biokunststoffe zu erweitern, soll das erarbeitete Konzept auf zwei industriell verf{\"u}gbare Proteintypen, Zein und Molkenproteinisolat (WPI), {\"u}bertragen werden. Als geeignete Materialklasse wurden Fetts{\"a}ureester der St{\"a}rke herausgearbeitet. Zun{\"a}chst fand ein Vergleich der S{\"a}urechlorid-Veresterung und der Umesterung von Fetts{\"a}urevinylestern statt, woraus letztere als geeignetere Methode hervorging. Durch Variation der Reaktionsparameter konnte diese optimiert und auf eine Serie der Fetts{\"a}urevinylester von Butanoat bis Stearat f{\"u}r DS-Werte bis zu 2,2-2,6 angewandt werden. M{\"o}glich war somit eine systematische Studie unter Variation der veresterten Fetts{\"a}ure sowie des Substitutionsgrades (DS). S{\"a}mtliche Produkte mit einem DS ab 1,5 wiesen eine ausgpr{\"a}gte L{\"o}slichkeit in organischen L{\"o}sungsmitteln auf wodurch sowohl die Aufnahme von NMR-Spektren als auch Molmassenbestimmung mittels Gr{\"o}ßenausschlusschromatographie mit gekoppelter Mehrwinkel-Laserlichtstreuung (GPC-MALLS) m{\"o}glich waren. Durch dynamische Lichtstreuung (DLS) wurde das L{\"o}slichkeitsverhalten veranschaulicht. S{\"a}mtliche Produkte konnten zu Filmen verarbeitet werden, wobei Materialien mit DS 1,5-1,7 hohe Zugfestigkeiten (bis zu 42 MPa) und Elastizit{\"a}tsmodule (bis 1390 MPa) aufwiesen. Insbesondere St{\"a}rkehexanoat mit DS <2 sowie St{\"a}rkebutanoat mit DS >2 hatten ein mechanisches Eigenschaftsprofil, welches insbesondere in Bezug auf die Festigkeit/Steifigkeit vergleichbar mit Verpackungsmaterialien wie Polyethylen war (Zugfestigkeit: 15-32 MPa, E-Modul: 300-1300 MPa). Zugfestigkeit und Elastizit{\"a}tsmodul nahmen mit steigender Kettenl{\"a}nge der veresterten Fetts{\"a}ure ab. Ester l{\"a}ngerkettiger Fetts{\"a}uren (C16-C18) waren spr{\"o}de. {\"U}ber Weitwinkel-R{\"o}ntgenstreuung (WAXS) und Infrarotspektroskopie (ATR-FTIR) konnte der Verlauf der Festigkeiten mit einer zunehmenden Distanz der St{\"a}rke im Material begr{\"u}ndet werden. Es konnten von DS und Kettenl{\"a}nge abh{\"a}ngige Glas{\"u}berg{\"a}nge detektiert werden, die kristallinen Strukturen der langkettigen Fetts{\"a}uren zeigten einen Schmelzpeak. Die Hydrophobie der Filme wurde anhand von Kontaktwinkeln >95° gegen Wasser dargestellt. Blends mit biobasierten Polyterpenen sowie den in der Arbeit hergestellten Zein-Acylderivaten erm{\"o}glichten eine weitere Verbesserung der Zugfestigkeit bzw. des Elastizit{\"a}tsmoduls hochsubstituierter Produkte. Eine thermoplastische Verarbeitung mittels Spritzgießen war sowohl f{\"u}r Produkte mit hohem als auch mittlerem DS-Wert ohne jeglichen Zusatz von Weichmachern m{\"o}glich. Es entstanden homogene, transparente Pr{\"u}fst{\"a}be. Untersuchungen der H{\"a}rte ergaben auch hier f{\"u}r St{\"a}rkehexanoat und -butanoat mit Polyethylen vergleichbare Werte. Ausgew{\"a}hlte Produkte wurden zu Fasern nach dem Schmelzspinnverfahren verarbeitet. Hierbei wurden insbesondere f{\"u}r hochsubstituierte Derivate homogenen Fasern erstellt, welche im Vergleich zur Gießfolie signifikant h{\"o}here Zugfestigkeiten aufwiesen. St{\"a}rkeester mit mittlerem DS ließen sich ebenfalls verarbeiten. Zun{\"a}chst wurden f{\"u}r eine {\"U}bertragung des Konzeptes auf die Proteine Zein und WPI verschiedene Synthesemethoden verglichen. Die Veresterung mit S{\"a}urechloriden ergab hierbei die h{\"o}chsten Werte. Im Hinblick auf eine gute L{\"o}slichkeit in organischen L{\"o}sungsmitteln wurde f{\"u}r WPI die Veresterung mit carbonyldiimidazol (CDI)-aktivierten Fetts{\"a}uren in DMSO und f{\"u}r Zein die Veresterung mit S{\"a}u-rechloriden in Pyridin bevorzugt. Es stellte sich heraus, dass acyliertes WPI zwar hydrophob, jedoch ohne Weichmacher nicht thermoplastisch verarbeitet werden konnte. Die Erstellung von Gießfolien f{\"u}hrte zu Spr{\"o}dbruchverhalten. Unter Zugabe der biobasierten {\"O}ls{\"a}ure wurde die Anwendung von acyliertem WPI als thermoplastischer Filler z. B. in Blends mit St{\"a}rkeestern dargestellt. Im Gegensatz hierzu zeigte acyliertes Zein Glas{\"u}berg{\"a}nge <100 °C bei ausreichender Stabilit{\"a}t (150-200 °C). Zeinoleat konnte ohne Weichmacher zu einer transparenten Gießfolie verarbeitet werden. S{\"a}mtliche Derivate erwiesen sich als ausgepr{\"a}gt hydrophob. Zeinoleat konnte {\"u}ber das Schmelzspinnverfahren zu thermoplastischen Fasern verarbeitet werden.},
  language  = {de}
}
@phdthesis{Mondal2013,
  author    = {Mondal, Suvendu Sekhar},
  title     = {Design of isostructural metal-imidazolate frameworks : application for gas storage},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-69692},
  school      = {Universit{\"a}t Potsdam},
  year      = {2013},
  abstract  = {The sharply rising level of atmospheric carbon dioxide resulting from anthropogenic emissions is one of the greatest environmental concerns facing our civilization today. Metal-organic frameworks (MOFs) are a new class of materials that constructed by metal-containing nodes bonded to organic bridging ligands. MOFs could serve as an ideal platform for the development of next generation CO2 capture materials owing to their large capacity for the adsorption of gases and their structural and chemical tunability. The ability to rationally select the framework components is expected to allow the affinity of the internal pore surface toward CO2 to be precisely controlled, facilitating materials properties that are optimized for the specific type of CO2 capture to be performed (post-combustion capture, precombustion capture, or oxy-fuel combustion) and potentially even for the specific power plant in which the capture system is to be installed. For this reason, significant effort has been made in recent years in improving the gas separation performance of MOFs and some studies evaluating the prospects of deploying these materials in real-world CO2 capture systems have begun to emerge. We have developed six new MOFs, denoted as IFPs (IFP-5, -6, -7, -8, -9, -10, IFP = Imidazolate Framework Potsdam) and two hydrogen-bonded molecular building block (MBB, named as 1 and 2 for Zn and Co based, respectively) have been synthesized, characterized and applied for gas storage. The structure of IFP possesses 1D hexagonal channels. Metal centre and the substituent groups of C2 position of the linker protrude into the open channels and determine their accessible diameter. Interestingly, the channel diameters (range : 0.3 to 5.2 {\AA}) for IFP structures are tuned by the metal centre (Zn, Co and Cd) and substituent of C2 position of the imidazolate linker. Moreover hydrogen bonded MBB of 1 and 2 is formed an in situ functionalization of a ligand under solvothermal condition. Two different types of channels are observed for 1 and 2. Materials contain solvent accessible void space. Solvent could be easily removed by under high vacuum. The porous framework has maintained the crystalline integrity even without solvent molecules. N2, H2, CO2 and CH4 gas sorption isotherms were performed. Gas uptake capacities are comparable with other frameworks. Gas uptake capacity is reduced when the channel diameter is narrow. For example, the channel diameter of IFP-5 (channel diameter: 3.8 {\AA}) is slightly lower than that of IFP-1 (channel diameter: 4.2 {\AA}); hence, the gas uptake capacity and Brunauer-Emmett-Teller (BET) surface area are slightly lower than IFP-1. The selectivity does not depend only on the size of the gas components (kinetic diameter: CO2 3.3 {\AA}, N2 3.6 {\AA} and CH4 3.8 ) but also on the polarizability of the surface and of the gas components. IFP-5 and-6 have the potential applications for the separation of CO2 and CH4 from N2-containing gas mixtures and CO2 and CH4 containing gas mixtures. Gas sorption isotherms of IFP-7, -8, -9, -10 exhibited hysteretic behavior due to flexible alkoxy (e.g., methoxy and ethoxy) substituents. Such phenomenon is a kind of gate effects which is rarely observed in microporous MOFs. IFP-7 (Zn-centred) has a flexible methoxy substituent. This is the first example where a flexible methoxy substituent shows the gate opening behavior in a MOF. Presence of methoxy functional group at the hexagonal channels, IFP-7 acted as molecular gate for N2 gas. Due to polar methoxy group and channel walls, wide hysteretic isotherm was observed during gas uptake. The N2 The estimated BET surface area for 1 is 471 m2 g-1 and the Langmuir surface area is 570 m2 g-1. However, such surface area is slightly higher than azolate-based hydrogen-bonded supramolecular assemblies and also comparable and higher than some hydrogen-bonded porous organic molecules.},
  language  = {en}
}
@phdthesis{Kroener2013,
  author    = {Kr{\"o}ner, Dominik},
  title     = {Analysis and control of light-induced processes in molecules: Electron and nuclear quantum dynamics for aspects of stereoisomerism and spectroscopy},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-70477},
  school      = {Universit{\"a}t Potsdam},
  year      = {2013},
  abstract  = {The habilitation thesis covers theoretical investigations on light-induced processes in molecules. The study is focussed on changes of the molecular electronic structure and geometry, caused either by photoexcitation in the event of a spectroscopic analysis, or by a selective control with shaped laser pulses. The applied and developed methods are predominantly based on quantum chemistry as well as on electron and nuclear quantum dynamics, and in parts on molecular dynamics. The studied scientific problems deal with stereoisomerism and the question of how to either switch or distinguish chiral molecules using laser pulses, and with the essentials for the simulation of the spectroscopic response of biochromophores, in order to unravel their photophysics. The accomplished findings not only explain experimental results and extend existing approaches, but also contribute significantly to the basic understanding of the investigated light-driven molecular processes. The main achievements can be divided in three parts: First, a quantum theory for an enantio- and diastereoselective or, in general, stereoselective laser pulse control was developed and successfully applied to influence the chirality of molecular switches. The proposed axially chiral molecules possess different numbers of "switchable" stable chiral conformations, with one particular switch featuring even a true achiral "off"-state which allows to enantioselectively "turn on" its chirality. Furthermore, surface mounted chiral molecular switches with several well-defined orientations were treated, where a newly devised highly flexible stochastic pulse optimization technique provides high stereoselectivity and efficiency at the same time, even for coupled chirality-changing degrees of freedom. Despite the model character of these studies, the proposed types of chiral molecular switches and, all the more, the developed basic concepts are generally applicable to design laser pulse controlled catalysts for asymmetric synthesis, or to achieve selective changes in the chirality of liquid crystals or in chiroptical nanodevices, implementable in information processing or as data storage. Second, laser-driven electron wavepacket dynamics based on ab initio calculations, namely time-dependent configuration interaction, was extended by the explicit inclusion of magnetic field-magnetic dipole interactions for the simulation of the qualitative and quantitative distinction of enantiomers in mass spectrometry by means of circularly polarized ultrashort laser pulses. The developed approach not only allows to explain the origin of the experimentally observed influence of the pulse duration on the detected circular dichroism in the ion yield, but also to predict laser pulse parameters for an optimal distinction of enantiomers by ultrashort shaped laser pulses. Moreover, these investigations in combination with the previous ones provide a fundamental understanding of the relevance of electric and magnetic interactions between linearly or non-linearly polarized laser pulses and (pro-)chiral molecules for either control by enantioselective excitation or distinction by enantiospecific excitation. Third, for selected light-sensitive biological systems of central importance, like e.g. antenna complexes of photosynthesis, simulations of processes which take place during and after photoexcitation of their chromophores were performed, in order to explain experimental (spectroscopic) findings as well as to understand the underlying photophysical and photochemical principles. In particular, aspects of normal mode mixing due to geometrical changes upon photoexcitation and their impact on (time-dependent) vibronic and resonance Raman spectra, as well as on intramolecular energy redistribution were addressed. In order to explain unresolved experimental findings, a simulation program for the calculation of vibronic and resonance Raman spectra, accounting for changes in both vibrational frequencies and normal modes, was created based on a time-dependent formalism. In addition, the influence of the biochemical environment on the electronic structure of the chromophores was studied by electrostatic interactions and mechanical embedding using hybrid quantum-classical methods. Environmental effects were found to be of importance, in particular, for the excitonic coupling of chromophores in light-harvesting complex II. Although the simulations for such highly complex systems are still restricted by various approximations, the improved approaches and obtained results have proven to be important contributions for a better understanding of light-induced processes in biosystems which also adds to efforts of their artificial reproduction.},
  language  = {en}
}