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@PHDTHESIS{Breuer:889587,
author = {Breuer, Timo},
othercontributors = {Müller, Thomas Ernst and Klankermayer, Jürgen},
title = {{S}ynthesis of oxazolidinones - a structural motif for
high-performance polymers},
school = {RWTH Aachen University},
type = {Dissertation},
address = {Aachen},
publisher = {RWTH Aachen University},
reportid = {RWTH-2023-01145},
pages = {1 Online-Ressource : Illustrationen, Diagramme},
year = {2022},
note = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
University 2023; Dissertation, RWTH Aachen University, 2022},
abstract = {This thesis concerns itself with the synthesis of
oxazolidinones and polyoxazolidinones from the corresponding
epoxides and isocyanates. The oxazolidinone moiety is
applied widely as constituent of antibiotics and auxiliaries
in enantioselective organic synthesis. Because of the
readily available raw materials, the oxazolidinone building
block is likewise of interest for the synthesis of
polyoxazolidinone-based high-performance thermoplastics. As
will be shown in this thesis, the oxazolidinone moiety is
obtained readily by conversion of epoxide and isocyanate,
when a suitable catalyst is applied. For application in the
polymerization reaction, the catalyst not only had to
provide excellent activity, but also outstanding
selectivity. The approach described in this thesis is
divided into two parts. The first part (Chapter II) deals
with the identification of a suitable catalyst. Catalysts
were assessed in a model system comprising a monofunctional
epoxide and isocyanate. The focus was placed on organic
Lewis acid-base catalysts, as the catalyst needed to be
metal-free. Literature-known tertiary ammonium salts were
the starting point. Azaspiro and imidazolium salts proved to
be selective catalysts, but their activity was not adequate
for industrial application. Comparing tetrabutyl ammonium
with tetrabutyl phosphonium bromide salts, we found that
phosphonium catalysts not only were more active, but also
provided similar or enhanced selectivity. The effect of the
chemical groups attached to the phosphonium center were
explored in detail. Substitution of alkyl by aryl groups led
to drastic increase in activity, while the high selectivity
was preserved. The activity was optimized further by
amending the aryl group with adequate substituents. The
catalysts developed this way were then applied to the
polymerization reaction of difunctional epoxides with
diisocyanates. As the polyoxazolidinone synthesis was
subject to the formation of various side products, the
selectivity of the catalyst was a central aspect. A suitable
reactor system and appropriate reaction parameters had to be
defined. Successfully, we synthesized polyoxazolidinones
that performed as high-performance thermoplastics. The
second part of this thesis (Chapter III) focuses on the
chemical and thermophysical properties of the thermoplastics
that were obtained. The polyoxazolidinones were thermally
highly stable with glass transition temperatures of
170-180°C and decomposition temperatures up to 400°C.
First tests showed that antioxidants have a beneficial
effect on the thermal stability of polyoxazolidinones at
elevated temperatures. Last but not least, the application
aspects were explored by spinning polymer samples into
fibers.},
cin = {154310 / 150000},
ddc = {540},
cid = {$I:(DE-82)154310_20190725$ / $I:(DE-82)150000_20140620$},
typ = {PUB:(DE-HGF)11},
doi = {10.18154/RWTH-2023-01145},
url = {https://publications.rwth-aachen.de/record/889587},
}
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