Graduate School Materials Science in Mainz

Mainz, Germany

Graduate School Materials Science in Mainz

Mainz, Germany
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Mangold C.,Graduate School Materials Science in Mainz | Mangold C.,Johannes Gutenberg University Mainz | Dingels C.,Johannes Gutenberg University Mainz | Obermeier B.,Johannes Gutenberg University Mainz | And 2 more authors.
Macromolecules | Year: 2011

Introduction of highly reactive vinyl ether moieties along a poly(ethylene glycol) (PEG) backbone has been realized by copolymerization of the novel epoxide monomer ethoxy vinyl glycidyl ether (EVGE) with ethylene oxide (EO). A series of copolymers with varying structure (block and random) as well as EVGE comonomer content (5-100%) with molecular weights in the range of 3,900-13,200 g/mol and narrow molecular weight distributions (M w/M n = 1.06-1.20) has been synthesized and characterized with respect to their microstructure and thermal properties. The facile transformation of the vinyl ether side chains in click type reactions was verified by two different post polymerization modification reactions: (i) thiol-ene addition and (ii) acetal formation, employing various model compounds. Both strategies are very efficient, resulting in quantitative conversion. The rapid and complete acetal formation with alcohols results in an acid-labile bond and is thus highly interesting with respect to biomedical applications that require slow or controlled release of a drug, while the thiol-ene addition to a vinyl ether prevents cross-linking efficiently compared to other double bonds. © 2011 American Chemical Society.

Spirin L.,Graduate School Materials Science in Mainz | Spirin L.,Leibniz Institute of Polymer Research | Kreer T.,Leibniz Institute of Polymer Research
ACS Macro Letters | Year: 2013

By means of molecular dynamics simulations we provide evidence for pronounced counterion immobilization in strongly compressed polyelectrolyte- brush bilayers, where the counterions represent the vast majority of mobile solvent particles. As a consequence, hydrodynamic effects are strongly suppressed and semidilute bilayers can respond to shear motion like electrically neutral bilayers at melt density. For large, time-independent shear rates, γ̇, the shear force scales as f(γ̇) ∼ γ̇0.69, in agreement with scaling theory. In this regime, polyelectrolyte-brush bilayers can stabilize highly nonstationary processes, such as the instantaneous inversion of the shear direction. The absence of hydrodynamic flow leads to a suppression of the overshoot for the shear force, which is found for electrically neutral bilayers with the same molecular parameters. We suggest that nature uses this mechanism to optimize biolubrication, for instance in synovial joints. © 2012 American Chemical Society.

Steinbach T.,Graduate School Materials Science in Mainz | Steinbach T.,Max Planck Institute for Polymer Research | Steinbach T.,Johannes Gutenberg University Mainz | Ritz S.,Max Planck Institute for Polymer Research | Wurm F.R.,Max Planck Institute for Polymer Research
ACS Macro Letters | Year: 2014

A small difference brings high control: In poly(phosphonate)s a stable carbon-phosphorus linkage attaches a side chain to a degradable poly(phosphoester)-backbone. A novel cyclic phosphonate monomer was developed to generate water-soluble aliphatic poly(ethylene methylphospho-nate)s. The monomer is accessible via a robust three-step protocol that can be easily scaled-up. Polymerization was initiated by a primary alcohol, mediated by 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in less than 2 h at 0 C. The molecular weight distributions were monomodal and very narrow (below 1.1) in all cases and molecular weights up to about 20000 g/mol have been prepared, proving the living nature of this polymerization. The resulting polymers were characterized in detail via NMR spectroscopy, size exclusion chromatography, and differential scanning calorimetry. Also, the reaction kinetics have been evaluated for several monomer/initiator ratios and found to guarantee a living behavior in all cases superior to other poly(phosphate)s reported earlier. The polymers are all highly water-soluble without a lower critical solution temperature and are nontoxic against HeLa cells. © 2014 American Chemical Society.

Pirro P.,Graduate School Materials Science in Mainz | Heussner F.,Graduate School Materials Science in Mainz | Serga A.A.,Graduate School Materials Science in Mainz | Hillebrands B.,Graduate School Materials Science in Mainz
Applied Physics Letters | Year: 2014

We present the experimental observation of localized parallel parametric generation of spin waves in a transversally in-plane magnetized Ni 81Fe19 magnonic waveguide. The localization is realized by combining the threshold character of parametric generation with a spatially confined enhancement of the amplifying microwave field. The latter is achieved by modulating the width of the microstrip transmission line which is used to provide the pumping field. By employing microfocussed Brillouin light scattering spectroscopy, we analyze the spatial distribution of the generated spin waves and compare it with numerical calculations of the field distribution along the Ni81Fe19 waveguide. This provides a local spin-wave excitation in transversally in-plane magnetized waveguides for a wide wave-vector range which is not restricted by the size of the generation area. © 2014 AIP Publishing LLC.

Pirro P.,Graduate School Materials Science in Mainz | Meyer T.,Graduate School Materials Science in Mainz | Heussner F.,Graduate School Materials Science in Mainz | Serga A.A.,Graduate School Materials Science in Mainz | Hillebrands B.,Graduate School Materials Science in Mainz
Applied Physics Letters | Year: 2014

We present parallel parametric amplification of coherently excited, propagating spin waves in a microstructured magnonic Ni81Fe 19 waveguide. Amplification is achieved by the pumping field generated by a microwave current flowing through a Cu micro-stripline underneath the waveguide. By employing microfocussed Brillouin light scattering spectroscopy, we investigate the spatial decay of the propagating spin waves and their amplification by means of parallel pumping. We analyze the dependence of the intensity of the amplified spin waves on the spin-wave excitation power, pumping power, and pumping duration, revealing the most efficient working point for a noise-free amplification. This paves the way for a frequency selective amplification of spin waves in microstructured magnonic circuits. © 2014 AIP Publishing LLC.

Tonhauser C.,Graduate School Materials Science in Mainz | Tonhauser C.,Johannes Gutenberg University Mainz | Schull C.,Graduate School Materials Science in Mainz | Schull C.,Johannes Gutenberg University Mainz | And 2 more authors.
ACS Macro Letters | Year: 2012

The introduction of acid-degradable acetal moieties into a hyperbranched polyether backbone has been achieved by the design of a novel epoxide-based degradable inimer. This new monomer, namely, 1-(glycidyloxy)ethyl ethylene glycol ether (GEGE), has been copolymerized in the anionic ring-opening polymerization (AROP) with ethylene oxide (EO) or glycidol (G), respectively, yielding branched polyethers, that is, P(EO-co-GEGE) and P(G-co-GEGE), that possess an adjustable amount of acid-cleavable acetal units. In addition, a novel class of multiarm star copolymers P(G-co-GEGE-g-EO) with acid-labile polyether core and PEG side chains was synthesized by using the P(G-co-GEGE) copolymers as multifunctional macroinitiators for AROP of EO. The new materials have been characterized in a detailed manner, revealing narrow to moderate molecular weight distributions. The degradation of these polymers under acidic conditions was characterized via SEC and 1H NMR spectroscopy. © 2012 American Chemical Society.

Tonhauser C.,Graduate School Materials Science in Mainz | Tonhauser C.,Johannes Gutenberg University Mainz | Alkan A.,Johannes Gutenberg University Mainz | Alkan A.,Max Planck Institute for Polymer Research | And 6 more authors.
Macromolecules | Year: 2013

The first ferrocene-containing epoxide monomer, ferrocenyl glycidyl ether (fcGE), is introduced. The monomer has been copolymerized with ethylene oxide (EO). This leads to electroactive, water-soluble, and thermoresponsive poly(ethylene glycol) (PEG) derived copolyethers. Anionic homo- and copolymerization of fcGE with EO was possible. Molecular weights could be varied from 2000 to 10 000 g mol-1, resulting in polymers with narrow molecular weight distribution (Mw/Mn = 1.07-1.20). The ferrocene (fc) content was varied from 3 to 30 mol %, obtaining water-soluble materials up to 10 mol % incorporation of the apolar ferrocenyl comonomer. Despite the steric bulk of fcGE, random copolymers were obtained, as confirmed via detailed 1H NMR kinetic measurements as well as 13C NMR studies of the polymer microstructure, including detailed triad characterization. In addition, the poly(fcGE) homopolymer has been prepared. All water-soluble copolyethers with fc side chains exhibited a lower critical solution temperature (LCST) in the range 7.2-82.2 C in aqueous solution, depending on the amount of fcGE incorporated. The LCST is further tunable by oxidation/reduction of ferrocene, as demonstrated by cyclic voltammetry. Investigation of the electrochemical properties by cyclovoltammetry revealed that the iron centers can be oxidized reversibly. Further, to evaluate the potential for biomedical application, cell viability tests of the fc-containing PEG copolymers were performed on a human cervical cancer cell line (HeLa), revealing good biocompatibility only in the case of low amounts of fcGE incorporated (below 5%). Significant cytotoxic behavior was observed with fcGE content exceeding 5%. The ferrocene-substituted copolyethers are promising for novel redox sensors and create new options for the field of organometallic (co)polymers in general. © 2013 American Chemical Society.

Golde S.,Graduate School Materials Science in Mainz | Golde S.,Johannes Gutenberg University Mainz | Palberg T.,Johannes Gutenberg University Mainz | Schope H.J.,Johannes Gutenberg University Mainz | Schope H.J.,University of Tübingen
Nature Physics | Year: 2016

Dynamical and structural heterogeneities have long been thought to play a key role in a unified picture of solidification in view of the two competitive processes of crystallization and vitrification. Here, we study these heterogeneities by means of a combination of dynamic and static light-scattering techniques applied to the simplest model system exhibiting crystallization and vitrification: the colloidal hard-sphere system. Our method enables us to quantify and correlate the temporal evolution of the amount of ordered clusters (precursors) and the amount of slow particles. Our analysis shows that their temporal evolutions are closely related and that there is an intimate link between structural and dynamic heterogeneities, crystal nucleation and the non-crystallization transition. © 2016 Macmillan Publishers Limited.

Klinker K.,Graduate School Materials Science in Mainz | Klinker K.,Johannes Gutenberg University Mainz | Barz M.,Johannes Gutenberg University Mainz
Macromolecular Rapid Communications | Year: 2015

Polypept(o)ides combine the multifunctionality and intrinsic stimuli-responsiveness of synthetic polypeptides with the "stealth"-like properties of the polypeptoid polysarcosine (poly(N-methyl glycine)). This class of block copolymers can be synthesized by sequential ring opening polymerization of α-amino acid N-carboxy-anhydrides (NCAs) and correspondingly of the N-substituted glycine N-carboxyanhydride (NNCA). The resulting block copolymers are characterized by Poisson-like molecular weight distributions, full end group integrity, and dispersities below 1.2. While polysarcosine may be able to tackle the currently arising issues regarding the gold standard PEG, including storage diseases in vivo and immune responses, the polypeptidic block provides the functionalities for a specific task. Additionally, polypeptides are able to form secondary structure motives, e.g., α-helix or β-sheets, which can be used to direct self-assembly in solution. In this feature article, we review the relatively new field of polypept(o)ides with respect to synthesis, characterization, and first data on the application of block copolypept(o)ides in nanomedicine. The summarized data already indicates the great potential of polypept(o)ides. Polypept(o)ides are hybrid materials consisting of polypeptides and polypeptoids. In this feature article, the synthetic methods, polymer properties, self-assembly in solution, and first applications as nanomedicines are summarized. Moreover, future perspectives for polypept(o)ides are outlined. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Golde S.,Graduate School Materials Science in Mainz | Golde S.,Johannes Gutenberg University Mainz | Franke M.,Graduate School Materials Science in Mainz | Schope H.J.,Graduate School Materials Science in Mainz
AIP Conference Proceedings | Year: 2013

We describe a new designed multispeckle correlation spectroscopy (MSCS) setup which uses a CCD-camera as optical detector. Due to the simultaneous detection of many coherence areas (speckles) we get a much better statistic than in standard dynamic light scattering (DLS) measurements. Furthermore the intermediate scattering function (ISF) for nonergodic samples can be determined from one measurement. A special feature of our setup is the direct imaging of the scattering volume on the CCD-camera. Therefore every speckle can be connected to its origin scattering volume. This space-resolution gives us the possibility to probe the particle dynamics at different sample positions. Further, we present frequency distributions of the intensity autocorrelation functions for a fluid and a metastable sample. © 2013 American Institute of Physics.

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