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Plenarvorträge - DPG-Tagungen

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Chemische Physik und Polymerphysik Dienstag<br />

tures decreases with decreasing film thickness. Destabilizing confined<br />

ultra-thin diblock copolymer films thus offers the opportunity to introduce<br />

two intrinsic lateral length scales, the characteristic periodicity of<br />

the micro phase separation structure Lo and the most prominent in-plane<br />

length of the dewetting structure Λ. While on a local scale the surface<br />

structure is nicely pictured by atomic force microscopy (AFM) to obtain<br />

CPP 15 POSTER: Polymers and Biomaterials<br />

a statistically significant information scattering is helpful. With grazing<br />

incidence small-angle scattering a length regime from molecular to<br />

micrometer-sized and thus comparable to AFM is addressed [2].<br />

[1] P.Müller-Buschbaum, R.Cubitt, W.Petry, Langmuir 19, 7778 (2003)<br />

[2] P. Müller-Buschbaum, Anal.Bioanal.Chem. 376, 3 (2003)<br />

Zeit: Dienstag 17:00–19:00 Raum: B<br />

CPP 15.1 Di 17:00 B<br />

Phase-behavior of bidisperse ferrocolloids — •Gabriel M.<br />

Range and Sabine H.L. Klapp — Stranski-Laboratorium für<br />

Physikalische und Theoretische Chemie, Sekr. TC7, Fakultät II,<br />

Technische Universität Berlin, Straße des 17. Juni 124, 10623 Berlin,<br />

Germany<br />

Using density functional theory in the modified mean-field (MMF) approximation<br />

we study the phase behavior of bidisperse ferrocolloids, consisting<br />

of a binary mixture of dipolar hard spheres (DHS). We focus on<br />

the fluid phase regime, where we consider both isotropic and anisotropic<br />

phases.<br />

In a recent MMF study of binary mixtures of equisized DHS, differing<br />

only in their dipole moments, we found a rich phase behavior resulting<br />

from the interplay of isotropic-to-ferroelectric and demixing transitions.<br />

In systems with strongly asymmetric dipole moments the isotropic-toferroelectric<br />

transition is shifted towards significantly lower temperatures<br />

compared to the one-component case, while the demixing transition becomes<br />

more and more dominating. We also found, that demixing is always<br />

accompanied by spontaneous ferroelectricity in the MMF approach.<br />

Based on these findings we analyze the relative importance of differing<br />

sizes versus differing dipole moments on the phase-behavior of ferrocolloids.<br />

We also investigate the influence of external fields, particularly on<br />

demixing and size separation.<br />

CPP 15.2 Di 17:00 B<br />

Properties and Crystallization of PNIPAM-co-PS core-shell microgels<br />

— •Thomas Hellweg — TU Berlin, Stranski Laboratorium,<br />

Strasse des 17.Juni 112, 10623 Berlin<br />

During the last decade thermosensitive hydrogels have received increasing<br />

attention due to their potential with respect to applications<br />

in drug delivery or as sensors. However, macroscopic gels have rather<br />

long equilibration times with respect to swelling and deswelling. In some<br />

cases it might take days until the equilibrium state is reached. Therefore,<br />

with respect to applications as sensors or drug delivery systems<br />

so called microgels have preferable properties compared to their macroscopic<br />

homologues. Recently, these particles were also investigated with<br />

respect to their crystallization behaviour. Due to their low polydispersity<br />

they form colloidal crystals in solution as usual hard-sphere colloids.<br />

Additionally, their response to temperature allows to vary the volume<br />

fraction over a wide range. Here, we are going to discuss the properties<br />

of poly((N-isopropyl acrylamide)-co-polystyrene (PNIPAM-co-PS) coreshell<br />

microgel particles with extended PNIPAM shells. The particles are<br />

characterized by dynamic light scattering (DLS), electron microscopy and<br />

SANS.<br />

CPP 15.3 Di 17:00 B<br />

Elastic and Thermal Properties of Nano-Particle Composites<br />

within Polymer Matrices — •Andrä le Coutre 1,2 , Bernd<br />

Wetzel 3 , Jörg Baller 1,2 , Ravi Bactavatchalou 1,2 , Ulrich<br />

Müller 1,2 , and Jan K. Krüger 1,2 — 1 Laboratoire Européen de<br />

Recherche Universitaire Saarland-Lorraine (LERUSL) — 2 Universität<br />

des Saarlandes, Fakultät für Physik und Elektrotechnik 7.2, Geb. 38,<br />

Saarbrücken, Germany — 3 Universität Kaiserslautern, Institut für<br />

Verbundwerkstoffe GmbH, Germany<br />

Composite systems gain importance in material science as well as in<br />

industrial applications. One aim is the improvement of the mechanical<br />

properties by reinforcement of polymer matrices with particles or fibers.<br />

By means of Brillouin spectroscopy we investigated the effective elastic<br />

modulus (compressional and shear modulus) of DGEBA/DETA-epoxies<br />

filled with Al2O3 and SiO2 nanoparticles with sizes below 50 nm. In addition<br />

to the stiffening as expected by averaging models of elastic properties,<br />

an enhanced stiffness for particle concentrations below 6% volume<br />

fraction is observed. The reason for this is assumed either to be an ef-<br />

fect of a special chemical affinity of the hardening component (DETA)<br />

to the nanoparticle surface or a structurizing effect of the surface on the<br />

surrounding epoxy matrix. As a kind of inverse situation DGEBA-filled<br />

nanoporous glass matrices were investigated giving hints for a structurizing<br />

effect of the inner surfaces to the DGEBA molecules.<br />

CPP 15.4 Di 17:00 B<br />

Micro-Nanopattern by Block Copolymer Micelle Nanolithography<br />

— •Roman Glass 1 , Martin Moeller 2 , and Joachim Spatz 1<br />

— 1 Institute for Physical Chemistry, Biophysical Chemistry, University<br />

of Heidelberg, Germany — 2 Deutsches Wollforschungsinstitut at the<br />

RWTH Aachen, Germany<br />

A key issue in the fabrication of functional nanostructures is the defined<br />

placement and connection of nanometre sized objects in periodic or<br />

aperiodic arrangements on surfaces with different chemical composition<br />

and electrical properties. The basis of our approach is the self-assembly<br />

of polystyrene-b-poly[2-vinylpyridine (HAuCl4)] diblock copolymer micelles<br />

into uniform monomicellar films on solid supports such as Si-wafers<br />

or glass cover slips. Subsequent hydrogen plasma treatment of micellar<br />

film causes deposition of Au-nanoparticles (between 2 and 8 nm) onto<br />

the substrate by entire removal of the polymer. The limitation of the<br />

separation distance between individual dots or the pattern geometry is<br />

overcome by combining self-assembly of diblock copolymer micelles with<br />

pre-structures formed by photo or e-beam lithography. Capillary forces of<br />

a retracting liquid film due to solvent evaporation on the pre-structured<br />

substrate push micelles in the corners of these defined topographies. A<br />

more direct process is demonstrated by applying monomicellar films as<br />

negative e-beam resist. This process is also feasible on electrical isolating<br />

substrates if the monomicellar film is coated in addition with a 5 nm<br />

thick conductive layer of carbon before e-beam treatment.<br />

CPP 15.5 Di 17:00 B<br />

Chemical Modification of microphase-separated Triblock Terpolymer<br />

Films — •Kristin Schmidt, Sabine Ludwigs, Andrej<br />

Voronv, Robert Magerle, and Georg Krausch — Physikalische<br />

Chemie II, Universität Bayreuth, Bayreuth, Germany<br />

In this presentation we discuss a polystyrene-b-poly(2vinylpyridine)-b-poly(tertbutylme<br />

thacrylate) triblock terpolymer<br />

(SVT) exhibiting a core-shell cylinder structure in bulk<br />

(φPS = 0.16, φP2V P = 0.21, φPtBMA = 0.63, Mw = 140k, Mw/Mn = 1.02)<br />

which was synthesized via sequential living anionic polymerization 1 .<br />

After annealing in controlled solvent vapour atmosphere thin films of<br />

these triblock terpolymer self-assemble into a highly ordered perforated<br />

lamellae structure with PS-core and a P2VP-shell in the PtBMA matrix<br />

phase.<br />

A chemical modification of the poly(tertbutylmethacrylate) matrix<br />

phase to poly(methacrylic acid) via acid-catalyzed saponification leads<br />

to a pH-responsive nanostructure which was investigated with scanning<br />

force microscopy in aqueous environment. Furthermore, we show that<br />

the perforated lamella might serve as a lithographic mask by selective<br />

UV-depolymerization of the poly(tertbutylmethacrylate) matrix phase 2 .<br />

1 Ludwigs, S.; Böker, A.; Abetz, V.; Müller, A.H.E.; Krausch, G. Polymer<br />

2003, 44, 6815<br />

2 Ludwigs, S.; Böker, A.; Voronov, A.; Rehse, N.; Magerle, R.; Krausch,<br />

G. Nature Materials 2003, 2, 744<br />

CPP 15.6 Di 17:00 B<br />

Response of polyelectrolyte multilayers to external stimuli —<br />

•Regine v. Klitzing 1 , John Wong 1 , and Roland Steitz 2 —<br />

1 Stranski-Laboratorium, TU Berlin, Strasse d. 17. Juni 112, 10623 Berlin<br />

— 2 Hahn-Meitner-Institut, Glienicker Strasse 100, 14109 Berlin<br />

The polymer films presented in this study were made by alternate adsorption<br />

of polyanions and polycations from aqueous solution onto solid

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