Plenarvorträge - DPG-Tagungen
Plenarvorträge - DPG-Tagungen
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