TY - GEN A1 - Schulze, Nicole A1 - Koetz, Joachim T1 - Kinetically Controlled Growth of Gold Nanotriangles in a Vesicular Template Phase by Adding a Strongly Alternating Polyampholyte N2 - This paper is focused on the temperature dependent synthesis of gold nanotriangles in a vesicular template phase, containing phosphatidylcholin and AOT, by adding the strongly alternating polyampholyte PalPhBisCarb. UV-vis absorption spectra in combination with TEM micrographs show that flat gold nanoplatelets are formed predominantly in presence of the polyampholyte at 45 °C. The formation of triangular and hexagonal nanoplatelets can be directly influenced by the kinetic approach, i.e., by varying the polyampholyte dosage rate at 45 °C. Corresponding zeta potential measurements indicate that a temperature dependent adsorption of the polyampholyte on the {111} faces will induce the symmetry breaking effect, which is responsible for the kinetically controlled hindered vertical and preferred lateral growth of the nanoplatelets. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 271 KW - Polyampholytes KW - Nanotriangles KW - Kinetically controlled nanocrystal growth Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-98380 ER - TY - JOUR A1 - Schulze, Nicole A1 - Koetz, Joachim T1 - Kinetically controlled growth of gold nanotriangles in a vesicular template phase by adding a strongly alternating polyampholyte JF - Journal of dispersion science and technology N2 - This paper is focused on the temperature-dependent synthesis of gold nanotriangles in a vesicular template phase, containing phosphatidylcholine and AOT, by adding the strongly alternating polyampholyte PalPhBisCarb. UV-vis absorption spectra in combination with TEM micrographs show that flat gold nanoplatelets are formed predominantly in the presence of the polyampholyte at 45°C. The formation of triangular and hexagonal nanoplatelets can be directly influenced by the kinetic approach, i.e., by varying the polyampholyte dosage rate at 45°C. Corresponding zeta potential measurements indicate that a temperature-dependent adsorption of the polyampholyte on the {111} faces will induce the symmetry breaking effect, which is responsible for the kinetically controlled hindered vertical and preferred lateral growth of the nanoplatelets. KW - Kinetically controlled nanocrystal growth KW - nanotriangles KW - polyampholytes Y1 - 2016 U6 - https://doi.org/10.1080/01932691.2016.1220318 SN - 0193-2691 SN - 1532-2351 VL - 38 IS - 8 SP - 1073 EP - 1078 PB - Taylor & Francis CY - Philadelphia ER - TY - JOUR A1 - Schulze, Nicole A1 - Appelhans, D. A1 - Tiersch, Brigitte A1 - Koetz, Joachim T1 - Morphological transformation of vesicles into tubular structures by adding polyampholytes or dendritic glycopolymers JF - Colloids and surfaces : an international journal devoted to the principles and applications of colloid and interface science ; A, Physicochemical and engineering aspects N2 - For the first time tubulating properties of spherical dendritic glycopolymers and linear alternating polyampholytes against non-uniform negatively charged giant vesicles are proven by light microscopy and cryo-scanning electron microscopy study. Real time observation of the morphological transformation from giant vesicles to tubular structures, simulating morphogenesis in living cells, is given by using the cationic and H-bond active dendritic glycopolymer accompanied by reducing the size of the giant vesicles and the evidence of vesicle-vesicle interaction which was only postulated in a previous study. Similar morphogenesis of non-uniform giant vesicles into tubular network structure can be observed by using a polyampholyte in the stretched conformation at pH 9. Pearl necklace and tubular network structure formation are also observed by applying anionic vesicles of significant smaller dimensions with average size dimensions of 35 nm, after adding the polyampholyte at pH 9. However, the fitting accuracy between the functional groups along the backbone chain of the polyampholyte on one side and the vesicle surface on the other side is of high importance for the transformation process by using polyampholytes. The resulting tubular and network structures offer new fields of application as microfluidic transport channels or template phases for the shape controlled formation of nanoparticles. (C) 2014 Elsevier B.V. All rights reserved. KW - Alternating polyampholytes KW - Maltose-modified PEI KW - Network structure KW - Template phase KW - Cryo-SEM KW - DLS Y1 - 2014 U6 - https://doi.org/10.1016/j.colsurfa.2014.06.007 SN - 0927-7757 SN - 1873-4359 VL - 457 SP - 326 EP - 332 PB - Elsevier CY - Amsterdam ER - TY - THES A1 - Schulze, Nicole T1 - Neue Templatphasen zur anisotropen Goldnanopartikelherstellung durch den Einsatz strukturbildender Polymere T1 - New template phases for anisotropic gold nanoparticle production through the use of structure-forming polymers N2 - Ziel der vorliegenden Arbeit war die Synthese und Charakterisierung von anisotropen Goldnanopartikeln in einer geeigneten Polyelektrolyt-modifizierten Templatphase. Der Mittelpunkt bildet dabei die Auswahl einer geeigneten Templatphase, zur Synthese von einheitlichen und reproduzierbaren anisotropen Goldnanopartikeln mit den daraus resultierenden besonderen Eigenschaften. Bei der Synthese der anisotropen Goldnanopartikeln lag der Fokus in der Verwendung von Vesikeln als Templatphase, wobei hier der Einfluss unterschiedlicher strukturbildender Polymere (stark alternierende Maleamid-Copolymere PalH, PalPh, PalPhCarb und PalPhBisCarb mit verschiedener Konformation) und Tenside (SDS, AOT – anionische Tenside) bei verschiedenen Synthese- und Abtrennungsbedingungen untersucht werden sollte. Im ersten Teil der Arbeit konnte gezeigt werden, dass PalPhBisCarb bei einem pH-Wert von 9 die Bedingungen eines Röhrenbildners für eine morphologische Transformation von einer vesikulären Phase in eine röhrenförmige Netzwerkstruktur erfüllt und somit als Templatphase zur formgesteuerten Bildung von Nanopartikeln genutzt werden kann. Im zweiten Teil der Arbeit wurde dargelegt, dass die Templatphase PalPhBisCarb (pH-Wert von 9, Konzentration von 0,01 wt.%) mit AOT als Tensid und PL90G als Phospholipid (im Verhältnis 1:1) die effektivste Wahl einer Templatphase für die Bildung von anisotropen Strukturen in einem einstufigen Prozess darstellt. Bei einer konstanten Synthesetemperatur von 45 °C wurden die besten Ergebnisse bei einer Goldchloridkonzentration von 2 mM, einem Gold-Templat-Verhältnis von 3:1 und einer Synthesezeit von 30 Minuten erzielt. Ausbeute an anisotropen Strukturen lag bei 52 % (Anteil an dreieckigen Nanoplättchen von 19 %). Durch Erhöhung der Synthesetemperatur konnte die Ausbeute auf 56 % (29 %) erhöht werden. Im dritten Teil konnte durch zeitabhängige Untersuchungen gezeigt werden, dass bei Vorhandensein von PalPhBisCarb die Bildung der energetisch nicht bevorzugten Plättchen-Strukturen bei Raumtemperatur initiiert wird und bei 45 °C ein Optimum annimmt. Kintetische Untersuchungen haben gezeigt, dass die Bildung dreieckiger Nanoplättchen bei schrittweiser Zugabe der Goldchlorid-Präkursorlösung zur PalPhBisCarb enthaltenden Templatphase durch die Dosierrate der vesikulären Templatphase gesteuert werden kann. In umgekehrter Weise findet bei Zugabe der Templatphase zur Goldchlorid-Präkursorlösung bei 45 °C ein ähnlicher, kinetisch gesteuerter Prozess der Bildung von Nanodreiecken statt mit einer maximalen Ausbeute dreieckigen Nanoplättchen von 29 %. Im letzten Kapitel erfolgten erste Versuche zur Abtrennung dreieckiger Nanoplättchen von den übrigen Geometrien der gemischten Nanopartikellösung mittels tensidinduzierter Verarmungsfällung. Bei Verwendung von AOT mit einer Konzentration von 0,015 M wurde eine Ausbeute an Nanoplättchen von 99 %, wovon 72 % dreieckiger Geometrien hatten, erreicht. N2 - The aim of the present work was the synthesis and characterization of anisotropic gold nanoparticles in a suitable polyelectrolyte-modified template phase. The focus was on the selection of a suitable template phase for the synthesis of uniform and reproducible anisotropic gold nanoparticles with the resulting special properties. In the synthesis of the anisotropic gold nanoparticles, the focus was on the use of vesicles as a template phase. Here, the influence of different structure-forming polymers (strongly alternating maleimide copolymers PalH, PalPh, PalPhCarb and PalPhBisCarb with different conformations) and surfactants (SDS, AOT - anionic surfactants) should be studied at various synthesis and separation conditions. In the first part of the work, it could be shown that PalPhBisCarb at pH 9 meets the requirements of a tubulating agent for a morphological transformation of a vesicular phase into a tubular network structure and thus can be used as a template phase for the shape-controlled formation of nanoparticles. In the second part of the work, it was shown that the template phase PalPhBisCarb (pH value of 9, concentration of 0.01 wt.%) with AOT as surfactant and PL90G as phospholipid (in the ratio 1:1) is the most effective choice of template phase for the formation of anisotropic structures in a one-step process. At a constant synthesis temperature of 45 °C, the best results were achieved with a gold chloride concentration of 2 mM, a gold-template ratio of 3:1 and a synthesis time of 30 minutes. The yield of anisotropic structures was 52% (triangular nanoplatelet content of 19%). By increasing the synthesis temperature, the yield could be increased to 56% (29%). In the third part, it was shown by time-dependent investigations that in the presence of PalPhBisCarb, the formation of the not energetically preferred platelet structures is initiated at room temperature and assumes an optimum at 45 °C. Kinetical studies have shown that the formation of triangular nanosheets can be controlled by the dosing rate of the vesicular template phase when the gold chloride precursor solution is gradually added to the PalPhBisCarb-containing template phase. Conversely, upon addition of the template phase to the gold chloride precursor solution at 45 °C, a similar, kinetically controlled process of formation of nanodimers takes place with a maximum yield of triangular nanoplatelets of 29%. In the last chapter, initial attempts were made to separate triangular nanoplatelets from the other geometries of the mixed nanoparticle solution by means of surfactant-induced depletion flocculation. When AOT was used at a concentration of 0.015 M, a yield of nanoplatelets of 99%, of which 72% had triangular geometries, was achieved. KW - Nanopartikel KW - nanoparticle KW - Templatphase KW - template phase KW - Gold KW - gold KW - anisotrop KW - anisotropic Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-409515 ER - TY - JOUR A1 - Schulze, Nicole A1 - Prietzel, Claudia Christina A1 - Koetz, Joachim T1 - Polyampholyte-mediated synthesis of anisotropic gold nanoplatelets JF - Colloid and polymer science : official journal of the Kolloid-Gesellschaft N2 - This paper focused on the synthesis of triangular nanoplatelets in the presence of a tubular network structure. The tubular network structure is formed by adding a strongly alternating polyampholyte, i.e., PalPhBisCarb, to a mixed vesicle system with a negatively charged bilayer containing phosphatidylcholin and AOT. Using the tubular network as a reducing agent in a one-step procedure, triangular and hexagonal nanoplatelets are formed. One can show that the nanoplatelet yield is enhanced by increasing the temperature and decreasing the reaction time. The platelet edge length can be decreased by heating the system up to 100 A degrees C. Due to specific interactions between PalPhBisCarb and the AOT/phospholipid bilayer, stacking and welding effects lead to the formation of ordered platelet structures. The reaction pathway to flat gold nanotriangles is discussed with regard to the twin plane growth model of gold nanoplates. KW - Polyampholytes KW - Tubular network structure KW - Anisotropic gold nanoplatelets KW - Nanocrystal growth KW - Nanotriangle stacking and welding Y1 - 2016 U6 - https://doi.org/10.1007/s00396-016-3890-y SN - 0303-402X SN - 1435-1536 VL - 294 SP - 1297 EP - 1304 PB - Springer CY - New York ER - TY - JOUR A1 - Schulze, Nicole A1 - Tiersch, B. A1 - Zenke, I. A1 - Koetz, Joachim T1 - Polyampholyte-tuned lyotrop lamellar liquid crystalline systems JF - COLLOID AND POLYMER SCIENCE N2 - The influence of a polyampholyte, i.e., poly(N,N’-diallyl-N,N’-dimethyl-altmaleamic carboxylate) (PalH), on the lamellar liquid crystalline (LC) system sodium dodecyl sulfate (SDS)/decanol/water was investigated by means of microdifferential scanning calorimetry, small-angle X-ray diffraction (SAXS), and cryo-scanning electron microscopy. After incorporating PalH into the lamellar liquid crystalline system, SAXS measurements show that three different LC phases exist: i.e., a swelling, slightly swelling, and non-swelling one. At pH 4, the positively charged polymer with an extended conformation can directly adsorb at the anionic head groups of the surfactant and more compact vesicles are formed at room temperature. At pH 9, the electrostatic interactions between the polyampholyte (in a more coiled conformation) and the sulfate head groups of the SDS are leveled off and incompact vesicles are formed at room temperature. That means in presence of the polyampholyte the morphology of the LC phase, i.e., the supramolecular vesicle structure, can be tuned by varying the pH and/or the temperature. KW - Polyampholytes KW - Lamellar liquid crystals KW - Vesicle formation KW - SAXS KW - Cryo-SEM KW - mu-DSC Y1 - 2013 U6 - https://doi.org/10.1007/s00396-013-2999-5 SN - 0303-402X SN - 1435-1536 VL - 291 IS - 11 SP - 2551 EP - 2559 PB - SPRINGER CY - NEW YORK ER -