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Weiche Materie Poster: Do., 13:00–15:30 D-P347
GISAXS investigation of sol-gel templated nanocomposite films
J. Perlich 1 , Y. Cheng 2 , J.S. Gutmann 2,3 , S.V. Roth 4 , P. Müller-Buschbaum 1
1 TU München, Physik-Department LS E13, James-Franck-Str. 1, D-85748 Garching,
Germany – 2 Max-Planck Institute for Polymer Research, Ackermannweg 10, D-55128
Mainz, Germany – 3 Institute for Physical Chemistry, Johannes Gutenberg University,
Jakob-Welder-Weg 10, D-55099 Mainz, Germany – 4 HASYLAB at DESY, Notkestr.
85, D-22603 Hamburg, Germany
We focus on the creation of nanostructured TiO2 thin films, which are of great interest
for many applications, due to their electrical performance. The performance is strongly
dependent on the morphology of the nanocomposite films, therefore it is very important
to prepare the desired morphology with high reproducibility and homogeneously spread
out over areas of cm 2 . For the preparation of the TiO2 nanocomposite films we combine
the amphilic diblock-copolymer PS-b-PEO, which acts as a templating agent, with an
inorganic sol-gel chemistry [1]. First, the diblock copolymer is dissolved in 1.4-dioxane,
which is a good solvent for both, the hydrophobic as well as the hydrophilic block of PSb-PEO.
Afterwards, hydrochloric acid (HCl) and titanium tetraisopropoxide (TTIP)
are added into the polymer solution as the source for the sol-gel process. Because
HCl and TTIP are poor solvents for the hydrophobic block, a so-called good-poorsolvent
pair induced phase separation leads to the formation of nanostructures by film
preparation via spin-coating. The different morphologies can be controlled by the
weight ratios of the solvents. In order to obtain crystalline TiO2 films as the final step
calcination is conducted at higher temperature in air.
For the investigation of the morphologies of the sol-gel templated nanocomposite
films grazing incidence small angle x-ray scattering (GISAXS) is performed at the synchrotron
beamline BW4 of the DESY HASYLAB facillity in Hamburg [2]. For the
experiments a morderate micro-focussed beamsize of 30 x 60 µm 2 is used, which also
enables to investigate local gradients of the thin film morphology. The GISAXS experiments
are conducted on various substrate materials with different surface roughnesses
and variations in the morphology of the nanocomposite films. The GISAXS scattering
patterns exhibit features clearly correlated to morphologies of ordered nanostructures,
whereas the calcination may cause further ordering. It is also observed that the
nanocomposite films on top of a surface with ordered nanoscale roughness influence
the scattering patterns.
In addition to the x-ray scattering, analytical methods as atomic force microscopy
(AFM) and scanning electron microscopy (SEM) are used for characterization. The
results of AFM and SEM characterization are in good agreement with the GISAXS
experiments.
[1] Y.-J. Cheng, J. S. Gutmann, J. Am. Chem. Soc. 128(14) (2006) 4658-4674
[2] P. Müller-Buschbaum, Anal.Bioanal.Chem. 376 (2003) 3