@article{MachatschekSaretiaLendlein2021, author = {Machatschek, Rainhard Gabriel and Saretia, Shivam and Lendlein, Andreas}, title = {Assessing the influence of temperature-memory creation on the degradation of copolyesterurethanes in ultrathin films}, series = {Advanced materials interfaces}, volume = {8}, journal = {Advanced materials interfaces}, number = {6}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {2196-7350}, doi = {10.1002/admi.202001926}, pages = {8}, year = {2021}, abstract = {Copolyesterurethanes (PDLCLs) based on oligo(epsilon-caprolactone) (OCL) and oligo(omega-pentadecalactone) (OPDL) segments are biodegradable thermoplastic temperature-memory polymers. The temperature-memory capability in these polymers with crystallizable control units is implemented by a thermomechanical programming process causing alterations in the crystallite arrangement and chain organization. These morphological changes can potentially affect degradation. Initial observations on the macroscopic level inspire the hypothesis that switching of the controlling units causes an accelerated degradation of the material, resulting in programmable degradation by sequential coupling of functions. Hence, detailed degradation studies on Langmuir films of a PDLCL with 40 wt\% OPDL content are carried out under enzymatic catalysis. The temperature-memory creation procedure is mimicked by compression at different temperatures. The evolution of the chain organization and mechanical properties during the degradation process is investigated by means of polarization-modulated infrared reflection absorption spectroscopy, interfacial rheology and to some extend by X-ray reflectivity. The experiments on PDLCL Langmuir films imply that degradability is not enhanced by thermal switching, as the former depends on the temperature during cold programming. Nevertheless, the thin film experiments show that the leaching of OCL segments does not induce further crystallization of the OPDL segments, which is beneficial for a controlled and predictable degradation.}, language = {en} } @article{KeckeisZellerJungetal.2021, author = {Keckeis, Philipp and Zeller, Enriko and Jung, Carina and Besirske, Patricia and Kirner, Felizitas and Ruiz-Agudo, Cristina and Schlaad, Helmut and C{\"o}lfen, Helmut}, title = {Modular toolkit of multifunctional block copoly(2-oxazoline)s for the synthesis of nanoparticles}, series = {Chemistry - a European journal}, volume = {27}, journal = {Chemistry - a European journal}, number = {32}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {0947-6539}, doi = {10.1002/chem.202101327}, pages = {8283 -- 8287}, year = {2021}, abstract = {Post-polymerization modification provides an elegant way to introduce chemical functionalities onto macromolecules to produce tailor-made materials with superior properties. This concept was adapted to well-defined block copolymers of the poly(2-oxazoline) family and demonstrated the large potential of these macromolecules as universal toolkit for numerous applications. Triblock copolymers with separated water-soluble, alkyne- and alkene-containing segments were synthesized and orthogonally modified with various low-molecular weight functional molecules by copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) and thiol-ene (TE) click reactions, respectively. Representative toolkit polymers were used for the synthesis of gold, iron oxide and silica nanoparticles.}, language = {en} } @phdthesis{Hechenbichler2021, author = {Hechenbichler, Michelle}, title = {New thermoresponsive amphiphilic block copolymers with unconventional chemical structure and architecture}, doi = {10.25932/publishup-54182}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-541822}, school = {Universit{\"a}t Potsdam}, pages = {XIX, 186}, year = {2021}, abstract = {Das Aggregationsverhalten von amphiphilen Blockcpoolymeren ist wichtig f{\"u}r zahlreiche Anwendungen, beispielsweise in der Waschmittelindustrie als Verdicker oder in der Pharmazie zur kontrollierten Freisetzung von Wirkstoffen. Wenn einer der Bl{\"o}cke thermoresponsiv ist, kann das Aggregationsverhalten zus{\"a}tzlich {\"u}ber die Temperatur gesteuert werden. W{\"a}hrend sich die bisherigen Untersuchungen solcher „intelligenten" Systeme zumeist auf einfache Diblockcopolymere beschr{\"a}nkt haben, wurde in der vorliegenden Arbeit die Komplexit{\"a}t der Polymere und damit die Vielseitigkeit dieser Systeme erh{\"o}ht. Dazu wurden spezifische Monomere, verschiedene Blockl{\"a}ngen, unterschiedliche Architekturen und zus{\"a}tzliche funktionelle Gruppen eingef{\"u}hrt. Durch systematische {\"A}nderungen wurde das Struktur-Wirkungsverhalten solcher thermoresponsiver amphiphiler Blockcopolymere untersucht. Dabei sind die Blockcopolymere typischerweise aus einem permanent hydrophoben „Sticker", einem permanent hydrophilen Block sowie einem thermoresponsiven Block, der ein Lower Critical Solution Temperature (LCST) Verhalten zeigt, aufgebaut. W{\"a}hrend der permanent hydrophile Block aus N,N Dimethylacrylamid (DMAm) bestand, wurden f{\"u}r den thermoresponsiven Block unterschiedliche Monomere, n{\"a}mlich N n Propylacrylamid (NPAm), N iso Propylacrylamid (NiPAm), N,N Diethylacrylamid (DEAm), N,N Bis(2 methoxyethyl)acrylamid (bMOEAm), oder N Acryloylpyrrolidin (NAP) mit entsprechend unterschiedlichen LCSTs von 25, 32, 33, 42 und 56 °C verwendet. Die Blockcopolymere wurden mittels aufeinanderfolgender reversibler Additions-Fragmentierungs-Ketten{\"u}bertragungspolymerisation (RAFT Polymerisation) hergestellt, um Polymere mit linearer, doppelt hydrophober sowie symmetrischer Quasi Miktoarm Architektur zu erhalten. Dabei wurden wohldefinierte Blockgr{\"o}ßen, Endgruppen und enge Molmassenverteilungen (Ɖ ≤ 1.3) erzielt. F{\"u}r komplexere Architekturen, wie die doppelt thermoresponsive und die nicht symmetrische Quasi Miktoarm Architekturen, wurde RAFT mit Atomtransfer-Radikalpolymerisation (ATRP) oder Single Unit Monomer Insertion (SUMI), kombiniert. Die dabei erhaltenen Blockcopolymere hatten ebenfalls wohldefinierte Blockl{\"a}ngen, allerdings war die Molmassenverteilung generell breiter (Ɖ ≤ 1.8) und Endgruppen gingen zum Teil verloren, da komplexere Syntheseschritte n{\"o}tig waren. Das thermoresponsive Verhalten in w{\"a}ssriger L{\"o}sung wurde mittels Tr{\"u}bungspunktmessung und Dynamischer Lichtstreuung (DLS) untersucht. Unterhalb der Phasen{\"u}berganstemperatur waren die Polymere l{\"o}slich in Wasser und mizellare Strukturen waren in der DLS sichtbar. Oberhalb der Phasen{\"u}bergangstemperatur war das Aggregationsverhalten dann stark abh{\"a}ngig von der Architektur und der chemischen Struktur des thermoresponsiven Blocks. Thermoresponsive Bl{\"o}cke aus PNAP und PbMOEAm mit einer Blockl{\"a}nge von DPn = 40 zeigten keinen Tr{\"u}bungspunkt (CP) bis hin zu 80 °C, da durch den angebrachten hydrophilen PDMAm Block die bereits hohe LCST der entsprechenden Homopolymere bei den Blockcopolymeren weiter erh{\"o}ht wurde. Blockcopolymere mit PNiPAm, PDEAm und PNPAm hinggeen zeigten abh{\"a}ngig von der Architektur und Blockgr{\"o}ße unterschiedliche CP's. Oberhalb der CP's waren gr{\"o}ßere Aggregate vor allem f{\"u}r die Blockcopolymere mit PNiPAm und PDEAm sichtbar, wohingegen der Phasen{\"u}bergang f{\"u}r Blockcopolymere mit PNPAm stark abh{\"a}ngig von der jeweiligen Architektur war und entsprechend kleinere oder gr{\"o}ßere Aggregate zeigte. Um das Aggregationsverhalten besser zu verstehen, wurden Fluoreszenzstudien an PDMAm und PNiPAm Homo und Blockcopolymeren mit linearer Architektur durchgef{\"u}hrt, welche mit komplement{\"a}ren Fluoreszenzfarbstoffen an den entgegengesetzten Kettenenden funktionalisiert wurden. Das thermoresponsive Verhalten wurde dabei sowohl in Wasser als auch in {\"O}l-in-Wasser Mikroemulsion untersucht. Die Ergebnisse zeigten, dass das Blockcopolymer sich, {\"a}hnlich wie die anderen hergestellten Architekturen, bei niedrigen Temperaturen wie ein Polymertensid verh{\"a}lt. Dabei bilden die hydrophoben Stickergruppen den Kern und die hydrophilen Arme die Corona der Mizelle. Oberhalb des Phasen{\"u}bergangs des PNiPAm Blocks verhielten sich die Blockcopolymere allerdings wie assoziative Telechele mit zwei nicht symmetrischen hydrophoben Endgruppen, die sich untereinander nicht mischten. Daher bildeten die Blockcopolymere anstatt aggregierter „Blumen"-Mizellen gr{\"o}ßere, dynamische Aggregate. Diese sind einerseits {\"u}ber die urspr{\"u}nglichen Mizellkerne bestehend aus den hydrophoben Sticker als auch {\"u}ber Cluster der kollabierten thermoresponsiven Bl{\"o}cke miteinander verkn{\"u}pft. In Mikroemulsion ist diese Art der Netzwerkbildung noch st{\"a}rker ausgepr{\"a}gt.}, language = {en} } @article{DaiMateGlebeetal.2018, author = {Dai, Xiaolin and Mate, Diana M. and Glebe, Ulrich and Garakani, Tayebeh Mirzaei and K{\"o}rner, Andrea and Schwaneberg, Ulrich and B{\"o}ker, Alexander}, title = {Sortase-mediated ligation of purely artificial building blocks}, series = {Polymers}, volume = {10}, journal = {Polymers}, number = {2}, publisher = {MDPI}, address = {Basel}, issn = {2073-4360}, doi = {10.3390/polym10020151}, pages = {13}, year = {2018}, abstract = {Sortase A (SrtA) from Staphylococcus aureus has been often used for ligating a protein with other natural or synthetic compounds in recent years. Here we show that SrtA-mediated ligation (SML) is universally applicable for the linkage of two purely artificial building blocks. Silica nanoparticles (NPs), poly(ethylene glycol) and poly(N-isopropyl acrylamide) are chosen as synthetic building blocks. As a proof of concept, NP-polymer, NP-NP, and polymer-polymer structures are formed by SrtA catalysis. Therefore, the building blocks are equipped with the recognition sequence needed for SrtA reaction-the conserved peptide LPETG-and a pentaglycine motif. The successful formation of the reaction products is shown by means of transmission electron microscopy (TEM), matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-ToF MS), and dynamic light scattering (DLS). The sortase catalyzed linkage of artificial building blocks sets the stage for the development of a new approach to link synthetic structures in cases where their synthesis by established chemical methods is complicated.}, language = {en} } @phdthesis{Schmidt2020, author = {Schmidt, Bernhard V. K. J.}, title = {Polymers, self-assembly and materials}, doi = {10.25932/publishup-48481}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-484819}, school = {Universit{\"a}t Potsdam}, pages = {VI, 350}, year = {2020}, abstract = {In der vorliegenden Arbeit wurden die Selbstorganisation von hydrophilen Polymeren, verst{\"a}rkte Hydrogele, sowie anorganische/Polymer Hybridmaterialien untersucht. Dabei beschreibt die Arbeit den Weg von Polymersynthese mittels verschiedener Methoden {\"u}ber Polymerselbstanordnung bis zur Herstellung von Polymermaterialien mit vielversprechenden Eigenschaften f{\"u}r zuk{\"u}nftige Anwendungen. Hydrophile Polymere wurden verwendet, um Mehrphasensysteme herzustellen, Wasser-in-Wasser Emulsionen zu bilden und selbstangeordneten Strukturen zu erzeugen, z. B. Partikel/Aggregate oder hohle Strukturen aus komplett wasserl{\"o}slichen Bausteinen. Die Strukturbildung in w{\"a}ssriger Umgebung wurde ferner f{\"u}r supramolekulare Hydrogele mit definierter Unterstruktur und reversiblem Gelierungsverhalten eingesetzt. Auf dem Gebiet der Hydrogele wurde das anorganische Material graphitisches Kohlenstoffnitrid (g-CN) als Photoinitiator f{\"u}r die Hydrogelsynthese und als Verst{\"a}rker der Gelstruktur beschrieben. Hierbei konnten Hydrogele mit herausragenden Eigenschaften generiert werden, z. B. hohe Kompressibilit{\"a}t, hohe Speichermodule oder Gleitf{\"a}higkeit. Die Kombinationen von g-CN mit verschiedenen Polymeren erlaubte es zudem neue Materialien f{\"u}r die Photokatalyse bereitzustellen. Als weiteres anorganisches Material wurden Metall-organische Ger{\"u}ste (MOFs) mit Polymeren kombiniert. Es konnte gezeigt werden, dass die Verwendung von MOFs in der Polymersynthese einen starken Einfluss auf die erzeugte Polymerstruktur hat und MOFs als Katalysator f{\"u}r Polymerisationen verwendet werden k{\"o}nnen. Zuletzt wurde die MOF Synthese an sich untersucht, wobei Polymeradditive oder L{\"o}sungsmittel eingesetzt wurden um die kristalline Struktur der MOFs zu modulieren. Insgesamt wurden hier verschiedene Errungenschaften f{\"u}r die Polymerchemie beschrieben, z.B. neuartige hydrophile Polymere und Hydrogele, die zur Zeit wichtige Materialien im Polymerbereich durch ihre vielversprechenden Anwendungen im biomedizinischen Sektor darstellen. Außerdem ergab die Kombination von Polymeren mit Materialien aus anderen Bereichen der Chemie, z. B. g-CN und MOFs, neue Materialien mit bemerkenswerten Eigenschaften, die ebenfalls von Interesse f{\"u}r zuk{\"u}nftige Anwendungen sind, z. B. Beschichtungen, Partikeltechnologie und Katalyse.}, 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{WagnerOdedShenharetal.2017, author = {Wagner, Tom and Oded, Meirav and Shenhar, Roy and B{\"o}ker, Alexander}, title = {Two-dimensionally ordered AuNP array formation via microcontact printing on lamellar diblock copolymer films}, series = {Polymers for advanced technologies}, volume = {28}, journal = {Polymers for advanced technologies}, publisher = {Wiley}, address = {Hoboken}, issn = {1042-7147}, doi = {10.1002/pat.3853}, pages = {623 -- 628}, year = {2017}, abstract = {The construction of nano-sized, two-dimensionally ordered nanoparticle (NP) superstructures is important for various advanced applications such as photonics, sensing, catalysis, or nano-circuitry. Currently, such structures are fabricated using the templated organization approach, in which the templates are mainly created by photo-lithography or laser-lithography and other invasive top-down etching procedures. In this work, we present an alternative bottom-up preparation method for the controlled deposition of NPs into hierarchical structures. Lamellar polystyrene-block-poly(2-vinylpyridinium) thin films featuring alternating stripes of neutral PS and positively charged P2VP domains serve as templates, allowing for the selective adsorption of negatively charged gold NPs. Dense NP assembly is achieved by a simple immersion process, whereas two-dimensionally ordered arrays of NPs are realized by microcontact printing (mu CP), utilizing periodic polydimethylsiloxane wrinkle grooves loaded with gold NPs. This approach enables the facile construction of hierarchical NP arrays with variable geometries. Copyright (C) 2016 John Wiley \& Sons, Ltd.}, language = {en} } @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} } @phdthesis{Dai2018, author = {Dai, Xiaolin}, title = {Synthesis of artificial building blocks for sortase-mediated ligation and their enzymatic linkage}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-420060}, school = {Universit{\"a}t Potsdam}, pages = {XIV, 125}, year = {2018}, abstract = {Das Enzym Sortase A katalysiert die Bildung einer Peptidbindung zwischen der Erkennungssequenz LPXTG und einem Oligoglycin. W{\"a}hrend vielf{\"a}ltige Ligationen zwischen Proteinen und verschiedenen Biomolek{\"u}len, Proteinen und kleinen synthetischen Molek{\"u}len, sowie Proteinen und Oberfl{\"a}chen durchgef{\"u}hrt wurden, besteht das Ziel dieser Arbeit darin, die Sortase-katalysierte Verlinkung von synthetischen Bausteinen zu untersuchen. Dies k{\"o}nnte den Weg bereiten f{\"u}r die Anwendung von Sortase A f{\"u}r chemische Aufgabenstellungen und eventuell sogar in den Materialwissenschaften. F{\"u}r diese grunds{\"a}tzliche Untersuchung wurden die verwendeten Bausteine zun{\"a}chst so einfach wie m{\"o}glich gehalten und leicht zug{\"a}ngliche SiO2 Nanopartikel und kommerziell erh{\"a}ltliche Polymerbl{\"o}cke ausgew{\"a}hlt. Die Bausteine wurden als erstes mit den Peptidsequenzen f{\"u}r Sortase-vermittelte Ligationen funktionalisiert. SiO2 Nanopartikel wurden mit Durchmessern von 60 und 200 nm hergestellt und mit C=C Doppelbindungen oberfl{\"a}chenmodifiziert. Dann wurden Peptide mit einem terminalen Cystein kovalent durch eine Thiol-en Reaktion angebunden. An die 60 nm NP wurden Peptide mit einem Pentaglycin und an die 200 nm Partikel Peptide mit LPETG Sequenz gebunden. Auf die gleiche Art und Weise wurden Peptide mit terminalem Cystein an die Polymere Polyethylenglykol (PEG) und Poly(N Isopropylacrylamid) (PNIPAM), die beide {\"u}ber C=C Endgruppen verf{\"u}gen, gebunden und G5-PEG und PNIPAM-LPETG Konjugate erhalten. Mit den vier Bausteinen wurden nun durch Sortase-vermittelte Ligation NP-Polymer Hybride, NP-NP und Polymer-Polymer Strukturen hergestellt und die Produkte u. a. durch Transmissionselektronen-mikroskopie, MALDI-ToF Massenspektrometrie sowie Dynamische Lichtstreuung charakterisiert. Die Verlinkung dieser synthetischen Bausteine konnte eindeutig gezeigt werden. Das Verwenden von kommerziell erh{\"a}ltlichen Polymeren hat jedoch zu einem Gemisch der Polymer-Peptid Konjugate mit unmodifiziertem Polymer gef{\"u}hrt, welches nicht gereinigt werden konnte. Deswegen wurden anschließend Synthesestrategien f{\"u}r reine Peptid-Polymer und Polymer-Peptid Konjugate als Bausteine f{\"u}r Sortase-vermittelte Ligationen entwickelt. Diese basieren auf der RAFT Polymerisation mit CTAs, die entweder an N- oder C-Terminus eines Peptids gebunden sind. GG-PNIPAM wurde durch das Anbinden eines geeigneten RAFT CTAs an Fmoc-GG in einer Veresterungsreaktion, Polymerisation von NIPAM und Abspalten der Fmoc Schutzgruppe synthetisiert. Weiterhin wurden mehrere Peptide durch Festphasen-Peptidsynthese erhalten. Die Anbindung eines RAFT CTAs (oder eines Polymerisationsinitiators) an den N-Terminus eines Peptids kann automatisiert als letzter Schritt in einem Peptid-Synthetisierer erfolgen. Die Synthese eines solchen Konjugats konnte in dem Zeithorizont dieser Arbeit noch nicht erreicht werden. Jedoch existieren mehrere vielversprechende Strategien, um diesen Ansatz mit verschiedenen Kopplungsreagenzien zur Anbindung des CTAs fortzusetzen. Solche Polymer Bausteine k{\"o}nnen in Zukunft f{\"u}r die Synthese von Protein-Polymer Konjugaten durch Sortase-Katalyse verwendet werden. Außerdem kann der Ansatz auch f{\"u}r die Synthese von Block-Copolymeren aus Polymerbl{\"o}cken mit Peptidmotiven an beiden Enden ausgebaut werden. Auch wenn bei der grunds{\"a}tzlichen Untersuchung im Rahmen dieser Arbeit Hybridstrukturen hergestellt wurden, die auch durch traditionelle chemische Synthesen erhalten werden k{\"o}nnten, wird ein Bausatz solcher Bausteine in Zukunft die Synthese neuer Materialien erm{\"o}glichen und kann auch den Weg f{\"u}r die Anwendung von Enzymen in den Materialwissenschaften ebnen. In Erg{\"a}nzung zu Nanopartikeln und Block-Copolymeren k{\"o}nnen dann auch Hybridmaterialien unter Einbezug von Protein-basierten Bausteinen hergestellt werden. Daher k{\"o}nnten Sortase Enzyme zu einem Werkzeug werden, welches etablierte chemische Verlinkungstechniken erg{\"a}nzt und mit den hoch spezifischen Peptidmotiven {\"u}ber funktionale Einheiten verf{\"u}gt, die orthogonal zu allen chemischen Gruppen sind.}, 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} } @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{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} } @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} }