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@PHDTHESIS{Campagna:976821,
author = {Campagna, Davide},
othercontributors = {Herrmann, Andreas and Pich, Andrij},
title = {{U}nmasking secondary amines by force: carbamoyloximes as
novel class of mechanoresponsive moieties in polymers},
school = {RWTH Aachen University},
type = {Dissertation},
address = {Aachen},
publisher = {RWTH Aachen University},
reportid = {RWTH-2024-00356},
pages = {1 Online-Ressource : Illustrationen},
year = {2023},
note = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
University 2024; Dissertation, RWTH Aachen University, 2023},
abstract = {The progress of smart polymeric materials towards life-like
systems requires the ability to spatially and temporally
control the amplification of specific chemical processes and
related signals by means of activable and switchable
catalysts. Among important stimuli, mechanical forces are
ubiquitous in any type of material and crucial in the
regulation of the biological activities. Polymer
mechanochemistry has become an important field which aims to
understand how mechanical stress dissipates and how it can
be productively exploited by incorporating molecular
structures in polymers that can respond to directional
tensile forces, undergoing specific transformations and
giving physical or chemical outputs (i.e., mechanophores).
Among these, the mechanical activation of catalysts (i.e.,
mechanocatalysts) represents an intriguing concept but it
has been limited so far to only few examples that comprise
the activation of transition metals, carbenes, and acids.
Amine functional groups are well known for their reactivity
and organocatalytic activity, besides being dominant in
biological processes. As these aspects match with the
advancements of smart polymers with life-like characters,
the design and realization of a novel mechanophore which
works as latent secondary amine generator was the major goal
of the project. The mechanochemical study was based on the
insertion of targeted mechanoresponsive structures in the
middle of linear polymer chains to which tensile force was
applied via ultrasonication in solution. After having
verified the mechanochemical inactivity of conventional
carbamates as amines protecting groups, a successful
mechanochemical generation of a secondary amine was achieved
with a carbamoylaldoxime moiety as validated mechanophore,
whose activation is postulated to proceed via an homolytic
scission of the oxime (N-O) bond followed by a radical
pathway that ultimately afforded the free secondary amine,
for which the triggered organocatalytic activity was
verified. Subsequently, a comparative survey with a
carbamoylketoxime variant evidenced interesting divergences
in the difference between the force-free and the
force-modified energetic pathways, manifested by enhanced
mechanochemical activity and thermal stability for the
ketoxime-based structure. These findings can pose the basis
for further optimizations and implementation of this novel
type of mechanophore in different polymeric materials,
achieving mechanical spatial and temporal control over
specific amplification processes that could serve for
improved smart features in our progressing materials (e.g.,
advancement of self-reinforcement and self-healing
properties).},
cin = {155910 / 150000 / 052200},
ddc = {540},
cid = {$I:(DE-82)155910_20190516$ / $I:(DE-82)150000_20140620$ /
$I:(DE-82)052200_20140620$},
typ = {PUB:(DE-HGF)11},
doi = {10.18154/RWTH-2024-00356},
url = {https://publications.rwth-aachen.de/record/976821},
}
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