@phdthesis{Justynska2005, author = {Justynska, Justyna}, title = {Towards a library of functional block copolymers : synthesis and colloidal properties}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-5907}, school = {Universit{\"a}t Potsdam}, year = {2005}, abstract = {Understanding the principles of self-organisation exhibited by block copolymers requires the combination of synthetic and physicochemical knowledge. The ability to synthesise block copolymers with desired architecture facilitates the ability to manipulate their aggregation behaviour, thus providing the key to nanotechnology. Apart from relative block volumes, the size and morphology of the produced nanostructures is controlled by the effective incompatibility between the different blocks. Since polymerisation techniques allowing for the synthesis of well-defined block copolymers are restricted to a limited number of monomers, the ability to tune the incompatibility is very limited. Nevertheless, Polymer Analogue Reactions can offer another possibility for the production of functional block copolymers by chemical modifications of well-defined polymer precursors. Therefore, by applying appropriate modification methods both volume fractions and incompatibility, can be adjusted. Moreover, copolymers with introduced functional units allow utilization of the concept of molecular recognition in the world of synthetic polymers. The present work describes a modular synthetic approach towards functional block copolymers. Radical addition of functional mercaptanes was employed for the introduction of diverse functional groups to polybutadiene-containing block copolymers. Various modifications of 1,2-polybutadiene-poly(ethylene oxide) block copolymer precursors are described in detail. Furthermore, extension of the concept to 1,2-polybutadiene-polystyrene block copolymers is demonstrated. Further investigations involved the self-organisation of the modified block copolymers. Formed aggregates in aqueous solutions of block copolymers with introduced carboxylic acid, amine and hydroxyl groups as well as fluorinated chains were characterised. Study of the aggregation behaviour allowed general conclusions to be drawn regarding the influence of the introduced groups on the self-organisation of the modified copolymers. Finally, possibilities for the formation of complexes, based on electrostatic or hydrogen-bonding interactions in mixtures of block copolymers bearing mutually interacting functional groups, were investigated.}, subject = {Blockcopolymere}, language = {en} } @phdthesis{Kubowicz2005, author = {Kubowicz, Stephan}, title = {Design and characterization of multicompartment micelles in aqueous solution}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-5752}, school = {Universit{\"a}t Potsdam}, year = {2005}, abstract = {Self-assembly of polymeric building blocks is a powerful tool for the design of novel materials and structures that combine different properties and may respond to external stimuli. In the past decades, most studies were focused on the self-assembly of amphiphilic diblock copolymers in solution. The dissolution of these block copolymers in a solvent selective for one block results mostly in the formation of micelles. The micellar structure of diblock copolymers is inherently limited to a homogeneous core surrounded by a corona, which keeps the micelle in solution. Thus, for drug-delivery applications, such structures only offer a single domain (the hydrophobic inner core) for drug entrapment. Whereas multicompartment micelles composed of a water-soluble shell and a segregated hydrophobic core are novel, interesting morphologies for applications in a variety of fields including medicine, pharmacy and biotechnology. The separated incompatible compartments of the hydrophobic core could enable the selective entrapment and release of various hydrophobic drugs while the hydrophilic shell would permit the stabilization of these nanostructures in physiological media. However, so far, the preparation and control of stable multicompartment micellar systems are in the first stages and the number of morphological studies concerning such micelles is rather low. Thus considerably little is known about their exact inner structures. In the present study, we concentrate on four different approaches for the preparation of multicompartment micelles by self-assembly in aqueous media. A similarity of all approaches was that hydrocarbon and fluorocarbon blocks were selected for all employed copolymers since such segments tend to be strongly incompatible, and thus favor the segregation into distinct domains. Our studies have shown that the self-assembly of the utilized copolymers in aqueous solution leads in three cases to the formation of multicompartment micelles. As expected the shape and size of the micelles depend on the molecular architecture and to some extent also on the way of preparation. These novel structured colloids may serve as models as well as mimics for biological structures such as globular proteins, and may open interesting opportunities for nanotechnology applications.}, subject = {Amphiphile Verbindungen}, language = {en} } @article{GarnierLaschewsky2006, author = {Garnier, Sebastien and Laschewsky, Andre}, title = {Non-ionic amphiphilic block copolymers by RAFT-polymerization and their self-organization}, series = {Colloid and polymer science : official journal of the Kolloid-Gesellschaft}, volume = {284}, journal = {Colloid and polymer science : official journal of the Kolloid-Gesellschaft}, publisher = {Springer}, address = {Berlin}, issn = {0303-402X}, doi = {10.1007/s00396-006-1484-9}, pages = {1243 -- 1254}, year = {2006}, abstract = {Water-soluble, amphiphilic diblock copolymers were synthesized by reversible addition fragmentation chain transfer polymerization. They consist of poly(butyl acrylate) as hydrophobic block with a low glass transition temperature and three different nonionic water-soluble blocks, namely, the classical hydrophilic block poly(dimethylacrylamide), the strongly hydrophilic poly(acryloyloxyethyl methylsulfoxide), and the thermally sensitive poly(N-acryloylpyrrolidine). Aqueous micellar solutions of the block copolymers were prepared and characterized by static and dynamic light scattering analysis (DLS and SLS). No critical micelle concentration could be detected. The micellization was thermodynamically favored, although kinetically slow, exhibiting a marked dependence on the preparation conditions. The polymers formed micelles with a hydrodynamic diameter from 20 to 100 nm, which were stable upon dilution. The micellar size was correlated with the composition of the block copolymers and their overall molar mass. The micelles formed with the two most hydrophilic blocks were particularly stable upon temperature cycles, whereas the thermally sensitive poly(N-acryloylpyrrolidine) block showed a temperature-induced precipitation. According to combined SLS and DLS analysis, the micelles exhibited an elongated shape such as rods or worms. It should be noted that the block copolymers with the most hydrophilic poly(sulfoxide) block formed inverse micelles in certain organic solvents.}, language = {en} } @article{SchreiberHosemannBeuermann2011, author = {Schreiber, Ulrike and Hosemann, Benjamin and Beuermann, Sabine}, title = {1H,1H,2H,2H-Perfluorodecyl-Acrylate-Containing block copolymers from ARGET ATRP}, series = {Macromolecular chemistry and physics}, volume = {212}, journal = {Macromolecular chemistry and physics}, number = {2}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1022-1352}, doi = {10.1002/macp.201000307}, pages = {168 -- 179}, year = {2011}, abstract = {Block copolymers of 1H,1H,2H,2H-perfluorodecyl acrylate (AC8) were obtained from ARGET ATRP. To obtain block copolymers of low dispersity the PAC8 block was synthesized in anisole with a CuBr(2)/PMDETA catalyst in the presence of tin(II) 2-ethylhexanoate as a reducing agent. The PAC8 block was subsequently used as macroinitiator for copolymerization with butyl and tert-butyl acrylate carried out in scCO(2). To achieve catalyst solubility in CO(2) two fluorinated ligands were employed. The formation of block copolymers was confirmed by size exclusion chromatography and DSC.}, language = {en} } @phdthesis{Miasnikova2012, author = {Miasnikova, Anna}, title = {New hydrogel forming thermo-responsive block copolymers of increasing structural complexity}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-59953}, school = {Universit{\"a}t Potsdam}, year = {2012}, abstract = {This work describes the synthesis and characterization of stimuli-responsive polymers made by reversible addition-fragmentation chain transfer (RAFT) polymerization and the investigation of their self-assembly into "smart" hydrogels. In particular the hydrogels were designed to swell at low temperature and could be reversibly switched to a collapsed hydrophobic state by rising the temperature. Starting from two constituents, a short permanently hydrophobic polystyrene (PS) block and a thermo-responsive poly(methoxy diethylene glycol acrylate) (PMDEGA) block, various gelation behaviors and switching temperatures were achieved. New RAFT agents bearing tert-butyl benzoate or benzoic acid groups, were developed for the synthesis of diblock, symmetrical triblock and 3-arm star block copolymers. Thus, specific end groups were attached to the polymers that facilitate efficient macromolecular characterization, e.g by routine 1H-NMR spectroscopy. Further, the carboxyl end-groups allowed functionalizing the various polymers by a fluorophore. Because reports on PMDEGA have been extremely rare, at first, the thermo-responsive behavior of the polymer was investigated and the influence of factors such as molar mass, nature of the end-groups, and architecture, was studied. The use of special RAFT agents enabled the design of polymer with specific hydrophobic and hydrophilic end-groups. Cloud points (CP) of the polymers proved to be sensitive to all molecular variables studied, namely molar mass, nature and number of the end-groups, up to relatively high molar masses. Thus, by changing molecular parameters, CPs of the PMDEGA could be easily adjusted within the physiological interesting range of 20 to 40°C. A second responsivity, namely to light, was added to the PMDEGA system via random copolymerization of MDEGA with a specifically designed photo-switchable azobenzene acrylate. The composition of the copolymers was varied in order to determine the optimal conditions for an isothermal cloud point variation triggered by light. Though reversible light-induced solubility changes were achieved, the differences between the cloud points before and after the irradiation were small. Remarkably, the response to light differed from common observations for azobenzene-based systems, as CPs decreased after UV-irradiation, i.e with increasing content of cis-azobenzene units. The viscosifying and gelling abilities of the various block copolymers made from PS and PMDEGA blocks were studied by rheology. Important differences were observed between diblock copolymers, containing one hydrophobic PS block only, the telechelic symmetrical triblock copolymers made of two associating PS termini, and the star block copolymers having three associating end blocks. Regardless of their hydrophilic block length, diblock copolymers PS11 PMDEGAn were freely flowing even at concentrations as high as 40 wt. \%. In contrast, all studied symmetrical triblock copolymers PS8-PMDEGAn-PS8 formed gels at low temperatures and at concentrations as low as 3.5 wt. \% at best. When heated, these gels underwent a gel-sol transition at intermediate temperatures, well below the cloud point where phase separation occurs. The gel-sol transition shifted to markedly higher transition temperatures with increasing length of the hydrophilic inner block. This effect increased also with the number of arms, and with the length of the hydrophobic end blocks. The mechanical properties of the gels were significantly altered at the cloud point and liquid-like dispersions were formed. These could be reversibly transformed into hydrogels by cooling. This thesis demonstrates that high molar mass PMDEGA is an easily accessible, presumably also biocompatible and at ambient temperature well water-soluble, non-ionic thermo-responsive polymer. PMDEGA can be easily molecularly engineered via the RAFT method, implementing defined end-groups, and producing different, also complex, architectures, such as amphiphilic triblock and star block copolymers, having an analogous structure to associative telechelics. With appropriate design, such amphiphilic copolymers give way to efficient, "smart" viscosifiers and gelators displaying tunable gelling and mechanical properties.}, language = {en} } @article{WeissWienkBoelensetal.2014, author = {Weiss, Jan and Wienk, Hans and Boelens, Rolf and Laschewsky, Andr{\´e}}, title = {Block copolymer micelles with an intermediate star-/flower-like structure studied by H-1 NMR relaxometry}, series = {Macromolecular chemistry and physics}, volume = {215}, journal = {Macromolecular chemistry and physics}, number = {9}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1022-1352}, doi = {10.1002/macp.201300753}, pages = {915 -- 919}, year = {2014}, abstract = {H-1 NMR relaxation is used to study the self-assembly of a double thermoresponsive diblock copolymer in dilute aqueous solution. Above the first transition temperature, at which aggregation into micellar structures is observed, the trimethylsilyl (TMS)-labeled end group attached to the shell-forming block shows a biphasic T-2 relaxation. The slow contribution reflects the TMS groups located at the periphery of the hydrophilic shell, in agreement with a star-like micelle. The fast T-2 contribution corresponds to the TMS groups, which fold back toward the hydrophobic core, reflecting a flower-like micelle. These results confirm the formation of block copolymer micelles of an intermediate nature (i.e., of partial flower-like and star-like character), in which a part of the TMS end groups folds back to the core due to hydrophobic interactions.}, language = {en} } @article{BrosnanSchlaadAntonietti2015, author = {Brosnan, Sarah M. and Schlaad, Helmut and Antonietti, Markus}, title = {Aqueous Self-Assembly of Purely Hydrophilic Block Copolymers into Giant Vesicles}, series = {Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition}, volume = {54}, journal = {Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition}, number = {33}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1433-7851}, doi = {10.1002/anie.201502100}, pages = {9715 -- 9718}, year = {2015}, abstract = {Self-assembly of macromolecules is fundamental to life itself, and historically, these systems have been primitively mimicked by the development of amphiphilic systems, driven by the hydrophobic effect. Herein, we demonstrate that self-assembly of purely hydrophilic systems can be readily achieved with similar ease and success. We have synthesized double hydrophilic block copolymers from polysaccharides and poly(ethylene oxide) or poly(sarcosine) to yield high molar mass diblock copolymers through oxime chemistry. These hydrophilic materials can easily assemble into nanosized (<500nm) and microsized (>5m) polymeric vesicles depending on concentration and diblock composition. Because of the solely hydrophilic nature of these materials, we expect them to be extraordinarily water permeable systems that would be well suited for use as cellular mimics.}, language = {en} } @article{LiedelLewinTsarkovaetal.2015, author = {Liedel, Clemens and Lewin, Christian and Tsarkova, Larisa and B{\"o}ker, Alexander}, title = {Reversible Switching of Block Copolymer Nanopatterns by Orthogonal Electric Fields}, series = {Small}, volume = {11}, journal = {Small}, number = {45}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1613-6810}, doi = {10.1002/smll.201502259}, pages = {6058 -- 6064}, year = {2015}, abstract = {It is demonstrated that the orientation of striped patterns can be reversibly switched between two perpendicular in-plane orientations upon exposure to electric fields. The results on thin films of symmetric polystyrene-block-poly(2-vinyl pyridine) polymer in the intermediate segregation regime disclose two types of reorientation mechanisms from perpendicular to parallel relative to the electric field orientation. Domains orient via grain rotation and via formation of defects such as stretched undulations and temporal phase transitions. The contribution of additional fields to the structural evolution is also addressed to elucidate the generality of the observed phenomena. In particular solvent effects are considered. This study reveals the stabilization of the meta-stable in-plane oriented lamella due to sequential swelling and quenching of the film. Further, the reorientation behavior of lamella domains blended with selective nanoparticles is addressed, which affect the interfacial tensions of the blocks and hence introduce another internal field to the studied system. Switching the orientation of aligned block copolymer patterns between two orthogonal directions may open new applications of nanomaterials as switchable electric nanowires or optical gratings.}, language = {en} } @phdthesis{Stahlhut2016, author = {Stahlhut, Frank}, title = {Entwicklung neuer triphiler, fluorkohlenstofffreier Blockcopolymere und Untersuchung ihrer Eigenschaften f{\"u}r Multikompartiment-Mizellen}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-96299}, school = {Universit{\"a}t Potsdam}, pages = {iv, 191}, year = {2016}, abstract = {Neue Systeme f{\"u}r triphile, fluorkohlenstofffreie Blockcopolymere in Form von Acrylat-basierten thermoresponsiven Blockcopolymeren sowie Acrylat- bzw. Styrol-basierten Terblock-Polyelektrolyten mit unterschiedlich chaotropen Kationen des jeweiligen polyanionischen Blocks wurden entwickelt. Multikompartiment-Mizellen, mizellare Aggregate mit ultrastrukturiertem hydrophobem Mizellkern die biologischen Strukturen wie dem Humanalbumin nachempfunden sind, sollten bei der Selbstorganisation in w{\"a}ssriger Umgebung entstehen. Durch Verwendung apolarer und polarer Kohlenwasserstoff-Dom{\"a}nen anstelle von fluorophilen Fluorkohlenstoff-Dom{\"a}nen sollte erstmals anhand solcher triphilen Systeme nachgewiesen werden, ob diese in der Lage zur selektiven Aufnahme hydrophober Substanzen in unterschiedliche Dom{\"a}nen des Mizellkerns sind. Mit Hilfe von sequentieller RAFT-Polymerisation wurden diese neuen triphilen Systeme hergestellt, die {\"u}ber einen permanent hydrophilen, eine permanent stark hydrophoben und einen dritten Block verf{\"u}gen, der durch externe Einfl{\"u}sse, speziell die Induzierung eines thermischen Coil-to-globule-{\"U}bergangs bzw. die Zugabe von organischen, hydrophoben Gegenionen von einem wasserl{\"o}slichen in einen polar-hydrophoben Block umgewandelt werden kann. Als RAFT-Agens wurde 4-(Trimethylsilyl)benzyl(3-(trimethylsilyl)-propyl)-trithiocarbonat mit zwei unterschiedlichen TMS-Endgruppen verwendet, das kontrollierte Reaktions-bedingungen sowie die molekulare Charakterisierung der komplexen Copolymere erm{\"o}glichte. Die beiden Grundtypen der linearen tern{\"a}ren Blockcopolymere wurden jeweils in zwei 2 Modell-Systeme, die geringf{\"u}gig in ihren chemischen Eigenschaften sowie in dem Blockl{\"a}ngenverh{\"a}ltnis von hydrophilen und hydrophoben Polymersegmenten variierten, realisiert und unterschiedliche Permutation der Bl{\"o}cke aufwiesen. Als ersten Polymertyp wurden amphiphile thermoresponsive Blockcopolymere verwendet. Modell-System 1 bestand aus dem permanent hydrophoben Block Poly(1,3-Bis(butylthio)-prop-2-yl-acrylat), permanent hydrophilen Block Poly(Oligo(ethylenglykol)monomethyletheracrylat) und den thermoresponsiven Block Poly(N,N'-Diethylacrylamid), dessen Homopolymer eine LCST-Phasen{\"u}bergang (LCST, engl.: lower critical solution temperature) bei ca. 36°C aufweist. Das Modell-System 2 bestand aus dem permanent hydrophilen Block Poly(2-(Methylsulfinyl)ethylacrylat), dem permanent hydrophoben Block Poly(2-Ethylhexylacrylat) und wiederum Poly(N,N'-Diethylacrylamid). Im tern{\"a}ren Blockcopolymer erh{\"o}hte sich, je nach Blocksequenz und relativen Blockl{\"a}ngen, der LCST-{\"U}bergang auf 50 - 65°C. Bei der Untersuchung der Selbstorganisation f{\"u}r die Polymer-Systeme dieses Typs wurde die Temperatur variiert, um verschieden mizellare {\"U}berstrukturen in w{\"a}ssriger Umgebung zu erzeugen bzw. oberhalb des LCST-{\"U}bergangs Multikompartiment-Mizellen nachzuweisen. Die Unterschiede in der Hydrophilie bzw. den sterischen Anspr{\"u}che der gew{\"a}hlten hydrophilen Bl{\"o}cke sowie die Variation der jeweiligen Blocksequenzen erm{\"o}glichte dar{\"u}ber hinaus die Bildung verschiedenster Morphologien mizellarer Aggregate. Der zweite Typ basierte auf ein Terblock-Polyelektrolyt-System mit Polyacrylaten bzw. Polystyrolen als Polymerr{\"u}ckgrat. Polymere ionische Fl{\"u}ssigkeiten wurden als Vorlage der Entwicklung zweier Modell-Systeme genommen. Eines der beiden Systeme bestand aus dem permanent hydrophilen Block Poly(Oligo(ethylenglykol)monomethyletheracrylat, dem permanent hydrophoben Block Poly(2-Ethylhexylacrylat) sowie dem Polyanion-Block Poly(3-Sulfopropylacrylat). Die Hydrophobie des Polyanion-Blocks variierte durch Verwendung großer organischer Gegenionen, n{\"a}mlich Tetrabutylammonium, Tetraphenylphosphonium und Tetraphenylstibonium. Analog wurde in einem weiteren System aus dem permanent hydrophilen Block Poly(4-Vinylbenzyltetrakis(ethylenoxy)methylether), dem permanent hydrophoben Block Poly(para-Methylstyrol) und Poly(4-Styrolsulfonat) mit den entsprechenden Gegenionen gebildet. Aufgrund unterschiedlicher Kettensteifigkeit in beiden Modell-Systemen sollte es bei der Selbstorganisation der mizellarer Aggregate zu unterschiedlichen {\"U}berstrukturen kommen. Mittels DSC-Messungen konnte nachgewiesen werden, dass f{\"u}r alle Modell-Systeme die Bl{\"o}cke in Volumen-Phase miteinander inkompatibel waren, was eine Voraussetzung f{\"u}r Multikompartimentierung von mizellaren Aggregaten ist. Die Gr{\"o}ße mizellarer Aggregate sowie der Einfluss externer Einfl{\"u}sse wie der Ver{\"a}nderung der Temperatur bzw. der Hydrophobie und Gr{\"o}ße von Gegenionen auf den hydrodynamischen Durchmesser mittels DLS-Untersuchungen wurden f{\"u}r alle Modell-Systeme untersucht. Die Ergebnisse zu den thermoresponsiven tern{\"a}ren Blockcopolymeren belegten , dass sich oberhalb der Phasen{\"u}bergangstemperatur des thermoresponsiven Blocks die Struktur der mizellaren Aggregate {\"a}nderte, indem der p(DEAm)-Block scheinbar kollabierte und so zusammen mit den permanent hydrophoben Block den jeweiligen Mizellkern bildete. Nach gewisser Equilibrierungszeit konnten bei Raumtemperatur dir urspr{\"u}nglichen mizellaren Strukturen regeneriert werden. Hingegen konnte f{\"u}r die Terblock-Polyelektrolyt-Systeme bei Verwendung der unterschiedlich hydrophoben Gegenionen kein signifikanter Unterschied in der Gr{\"o}ße der mizellaren Aggregate beobachtet werden. Zur Abbildung der mizellaren Aggregate mittels kryogene Transmissionselektronenmikroskopie (cryo-TEM) der mizellaren Aggregate war mit Poly(1,3-Bis(butylthio)-prop-2-yl-acrylat) ein Modell-System so konzipiert, dass ein erh{\"o}hter Elektronendichtekontrast durch Schwefel-Atome die Visualisierung ultrastrukturierter hydrophober Mizellkerne erm{\"o}glichte. Dieser Effekt sollte in den Terblock-Polyelektrolyt-Systemen auch durch die Gegenionen Tetraphenylphosphonium und Tetraphenylstibonium nachgestellt werden. W{\"a}hrend bei den thermoresponsiven Systemen auch oberhalb des Phasen{\"u}bergangs kein Hinweis auf Ultrastrukturierung beobachtet wurde, waren f{\"u}r die Polyelektrolyt-Systeme, insbesondere im Fall von Tetraphenylstibonium als Gegenion {\"U}berstrukturen zu erkennen. Der Nachweis der Bildung von Multikompartiment-Mizellen war f{\"u}r beide Polymertypen mit dieser abbildenden Methode nicht m{\"o}glich. Die Unterschiede in der Elektronendichte einzelner Bl{\"o}cke m{\"u}sste m{\"o}glicherweise weiter erh{\"o}ht werden um Aussagen diesbez{\"u}glich zu treffen. Die Untersuchung von ortsspezifischen Solubilisierungsexperimenten mit solvatochromen Fluoreszenzfarbstoffen mittels „steady-state"-Fluoreszenzspektroskopie durch Vergleich der Solubilisierungsorte der Terblockcopolymere bzw. -Polyelektrolyte mit den jeweiligen Solubilisierungsorten von Homopolymer- und Diblock-Vorstufen sollten den qualitativen Nachweis der Multikompartimentierung erbringen. Aufgrund der geringen Mengen an Farbstoff, die f{\"u}r die Solubilisierungsexperimente eingesetzt wurden zeigten DLS-Untersuchungen keine st{\"o}renden Effekte der Sonden auf die Gr{\"o}ße der mizellaren Aggregate. Jedoch erschwerten Quench-Effekte im Falle der Polyelektrolyt Modell-Systeme eine klare Interpretation der Daten. Im Falle der Modell-Systeme der thermoresponsiven Blockcopolymere waren dagegen deutliche solvatochrome Effekte zwischen der Solubilisierung in den mizellaren Aggregaten unterhalb und oberhalb des Phasen{\"u}bergangs zu erkennen. Dies k{\"o}nnte ein Hinweis auf Multikompartimentierung oberhalb des LCST-{\"U}bergangs sein. Ohne die Informationen einer Strukturanalyse wie z.B. der R{\"o}ntgen- oder Neutronenkleinwinkelstreuung (SAXS oder SANS), kann nicht abschließend gekl{\"a}rt werden, ob die Solubilisierung in mizellaren hydrophoben Dom{\"a}nen des kollabierten Poly(N,N'-Diethylacrylamid) erfolgt oder in einer Mischform von mizellaren Aggregaten mit gemittelter Polarit{\"a}t.}, language = {de} } @article{WagnerLazarSchnakenbergetal.2016, author = {Wagner, Tom and Lazar, Jaroslav and Schnakenberg, Uwe and B{\"o}ker, Alexander}, title = {In situ Electrothemical Impedance Spectroscopy of Electrostatically Driven Selective Gold Nanoparticle Adsorption on Block Copolymer Lamellae}, series = {Trials}, volume = {8}, journal = {Trials}, publisher = {American Chemical Society}, address = {Washington}, issn = {1944-8244}, doi = {10.1021/acsami.6b07708}, pages = {27282 -- 27290}, year = {2016}, abstract = {Electrostatic attraction between charged nano particles and oppositely charged nanopatterned polymeric films enables tailored structuring of functional nanoscopic surfaces. The bottom-up fabrication of organic/inorganic composites for example bears promising potential toward cheap fabrication of catalysts, optical sensors, and the manufacture of miniaturized electric circuitry. However, only little is known about the time-dependent adsorption behavior and the electronic or ionic charge transfer in the film bulk and at interfaces during nanoparticle assembly via electrostatic interactions. In situ electrochemical impedance spectroscopy (EIS) in combination with a microfluidic system for fast and reproducible liquid delivery was thus applied to monitor the selective deposition of negatively charged gold nanoparticles on top of positively charged poly(2-vinylpyridinium) (qP2VP) domains of phase separated lamellar poly(styrene)-block-poly(2-vinylpyridinium) (PS-b-qP2VP) diblock copolymer thin films. The acquired impedance data delivered information with respect to interfacial charge alteration, ionic diffusion, and the charge dependent nanoparticle adsorption kinetics, considering this yet unexplored system. We demonstrate that the selective adsorption of negatively charged gold nanoparticles (AuNPs) on positively charged qP2VP domains of lamellar PS-b-qP2VP thin films can indeed be tracked by EIS. Moreover, we show that the nanoparticle adsorption kinetics and the nanoparticle packing density are functions of the charge density in the qP2VP domains.}, language = {en} }