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M. Tress et al.
dissolved in toluene together with the vinyl-terminated iPS. Under dry argon atmosphere the hydrosilylation reaction to connect the iPS to the edges of the octakis
(dimethylsilyloxy) silesquioxane was initiated by adding a xylene solution with
Karstedt catalyst. After 2 h reaction time the solvent was removed by drying, and
then, the product was purified in a chloroform solution and fractionation by methanol.
The resulting star-polymers have 6–8 iPS arms attached to a polyhedral oligomeric
silesquioxane (POSS) molecule. Details on the synthesis were published elsewhere
[17].
2.2 Crystallization Procedure
In order to remove any thermal history before each experiment, the sample is heated
above its melting temperature of T m = 206 °C (~480 K). The amorphous state is
prepared by annealing at 210 °C for about 1 h in the case of dielectric and calorimetric
experiments and 4 h before the infrared measurements. The sample was crystallized
at T c = 460 K for up to 20 h. In the case of the dielectric experiments, the sample
dynamics was probed at certain times during and after the crystallization whereby
the sample had to be cooled rapidly from T c to T g + 25 K (335 K) and below for
each measurement. In the case of the infrared measurements spectra are collected
continuously at T c and molecular vibrations are monitored.
2.3 Broadband Dielectric Spectroscopy (BDS)
The broadband dielectric spectroscopy (BDS) measurements were performed with an
Alpha-A Analyzer (Novocontrol) connected to a Quatro cryo-system (Novocontrol)
in a frequency and temperature range from 0.1 Hz to 1 MHz and 350 to 480 K,
respectively.
The sample was prepared by spin-coating from a toluene solution onto a piece of
highly conductive and ultra-flat silicon as lower electrode after a thorough cleaning by
acetone rinse, plasma treatment (100 W for 5 min) and expurgation with supercritical
CO 2 [12]. The film of several hundred nm thickness was then covered by a top
electrode also made of highly conductive silicon which had silica nano-structures
as spacers with a height of 550 nm. These spacers prevent an electrical short circuit
between the electrodes and establish a free upper interface of the film which allows
for relaxation of mechanical stresses and structural rearrangements during potential
phase transitions.
M. Tress et al.
dissolved in toluene together with the vinyl-terminated iPS. Under dry argon atmosphere the hydrosilylation reaction to connect the iPS to the edges of the octakis
(dimethylsilyloxy) silesquioxane was initiated by adding a xylene solution with
Karstedt catalyst. After 2 h reaction time the solvent was removed by drying, and
then, the product was purified in a chloroform solution and fractionation by methanol.
The resulting star-polymers have 6–8 iPS arms attached to a polyhedral oligomeric
silesquioxane (POSS) molecule. Details on the synthesis were published elsewhere
[17].
2.2 Crystallization Procedure
In order to remove any thermal history before each experiment, the sample is heated
above its melting temperature of T m = 206 °C (~480 K). The amorphous state is
prepared by annealing at 210 °C for about 1 h in the case of dielectric and calorimetric
experiments and 4 h before the infrared measurements. The sample was crystallized
at T c = 460 K for up to 20 h. In the case of the dielectric experiments, the sample
dynamics was probed at certain times during and after the crystallization whereby
the sample had to be cooled rapidly from T c to T g + 25 K (335 K) and below for
each measurement. In the case of the infrared measurements spectra are collected
continuously at T c and molecular vibrations are monitored.
2.3 Broadband Dielectric Spectroscopy (BDS)
The broadband dielectric spectroscopy (BDS) measurements were performed with an
Alpha-A Analyzer (Novocontrol) connected to a Quatro cryo-system (Novocontrol)
in a frequency and temperature range from 0.1 Hz to 1 MHz and 350 to 480 K,
respectively.
The sample was prepared by spin-coating from a toluene solution onto a piece of
highly conductive and ultra-flat silicon as lower electrode after a thorough cleaning by
acetone rinse, plasma treatment (100 W for 5 min) and expurgation with supercritical
CO 2 [12]. The film of several hundred nm thickness was then covered by a top
electrode also made of highly conductive silicon which had silica nano-structures
as spacers with a height of 550 nm. These spacers prevent an electrical short circuit
between the electrodes and establish a free upper interface of the film which allows
for relaxation of mechanical stresses and structural rearrangements during potential
phase transitions.