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Characterisation of thermallyinduced phase separation in polymer blend thin layers using chip calorimetry and SPM related techniques

Friday, 15 October, 2010 - 17:00
Campus: Brussels Humanities, Sciences & Engineering campus
Nicolaas-Alexander Gotzen
phd defence

The aim of this PhD was the fundamental study of phase separation in amorphous
polymer blend thin films, using thermal techniques that allow a (direct) comparison
between phase separation in bulk and in thin films. Two approaches have been
followed: ‘cantilever-based thermal analysis’, and ‘chip-based thermal analysis’.

Cantilever-based thermal analysis comprises both high temperature atomic force
microscopy as a tool to study in-situ the morphology development upon phase
separation at high temperatures, and local thermal analysis measurements using
thermal cantilevers on specific locations of the specimen’s surface.

Chip-based thermal analysis, on the other hand, allows the calorimetric
measurement of (sub)nanogram samples. A new methodology was developed
allowing the construction of the state diagram, and the investigation of the kinetics
of mixing/demixing in thin films, evidencing the influence of the increased surface to
volume ratio in thin films on the phase separation behavior.

This PhD study showed that both approaches are useful for the monitoring of phase
transitions in polymer blend thin layers. Cantilever-based thermal analysis can
provide ‘microscopic’ information on a lateral sub-micron level, while chip-based
thermal analysis offers ‘macroscopic’ information on samples of sub-nanogram level,
such as films of a few nm thickness.

Although this is a more fundamental investigation, the developed methodologies can
easily be transferred to materials used in real-life applications. Examples are smart
stimuli (thermo)-responsive polymer surfaces, protective coatings (with/without selfhealing
capacity), thermoset coatings or active layers of organic solar cells.