dc.contributor.advisor | Vana, Philipp Prof. Dr. | |
dc.contributor.author | Hendrich, Michael | |
dc.date.accessioned | 2016-12-13T09:04:05Z | |
dc.date.available | 2016-12-13T09:04:05Z | |
dc.date.issued | 2016-12-13 | |
dc.identifier.uri | http://hdl.handle.net/11858/00-1735-0000-002B-7CD8-0 | |
dc.identifier.uri | http://dx.doi.org/10.53846/goediss-6039 | |
dc.language.iso | eng | de |
dc.publisher | Niedersächsische Staats- und Universitätsbibliothek Göttingen | de |
dc.rights.uri | http://creativecommons.org/licenses/by-nc-nd/4.0/ | |
dc.subject.ddc | 540 | de |
dc.title | Biomimetic Polymer Systems via RAFT Polymerization - Routes to High-Performance Materials | de |
dc.type | doctoralThesis | de |
dc.contributor.referee | Vana, Philipp Prof. Dr. | |
dc.date.examination | 2016-12-02 | |
dc.description.abstracteng | Nature provides numerous examples of structural materials with
outstanding mechanical properties. An especially intriguing material is
spider dragline silk that outmatches man-made high-performance fibers
such as Kevlar or high-tensile steel. Therefore, it has been a prolific
source of inspiration to research in various scientific fields.
In this thesis, the macromolecular structure of spider dragline silk
was adapted by preparation of multiblock copolymers with hydrogen
bonding domains, and soft, amorphous segments, and their mechanical
performance was evaluated via tensile testing. The multiblock copolymer
structure was achieved by the use of polyfunctional RAFT (reversible
addition−fragmentation chain transfer) agents with trithiocarbonate
groups acting as junction points between individual blocks. For
comparison, triblock copolymers were prepared with similar block
lengths and composition. It was found that the multiblock copolymers
show superior mechanical performance, exibiting higher elasticity,
tensile strength and toughness. After initial tensile testing and failure of
test specimens, samples of both tri- and multiblock copolymers could be
regenerated via thermal annealing. Then, significantly enhanced sample
toughness was observed which indicated an increased number of
hydrogen bonding interactions.
In order to expand the scope of polyfunctional RAFT agents for
tailored material design, the RAFT polymerization of polyfunctional
trithiocarbonates was explored in closer detail. During polymerization,
RAFT groups being connected to polymer segments are redistributed
between macromolecular chains and a characteristic distribution of
RAFT groups in the polymer is obtained. This concept was used for the
preparation of polystyrene samples by mixing a bi- and a polyfunctional
RAFT agent in specific ratios. By characterizing the prepared samples via
size-exclusion chromatography (SEC) it could be demonstrated, that the
resulting molar mass and hence the number of RAFT groups per
macromolecule can be tailored.To exploit this concept for advanced material design, star-shaped
RAFT agent was mixed with polyfunctional RAFT agent and multiblock
copolymers of styrene and n-butyl acrylate were prepared that exhibited
the star-shaped topological features. The mechanical properties of the
prepared materials were investigated via tensile testing. Compared with
multiblock copolymers obtained from pure polyfunctional RAFT agents,
significantly improved material toughness was observed for the
materials that were prepared using the novel mixing approach.
Additionally, strain whitening of polymer samples could be prevented
and it was demonstrated, that the mixing approach yields materials with
superior toughness than conventional blends of star and multiblock
copolymers. In conclusion, this work could demonstrate excellent
versatility of polyfunctional RAFT agents for the preparation of highperformance
materials. | de |
dc.contributor.coReferee | Samwer, Konrad Prof. Dr. | |
dc.contributor.thirdReferee | Geil, Burkhard Prof. Dr. | |
dc.contributor.thirdReferee | Buback, Michael Prof. Dr. | |
dc.contributor.thirdReferee | Ehlers, Florian Dr. | |
dc.contributor.thirdReferee | Zeuch, Thomas PD Dr. | |
dc.subject.eng | Biomimetic Polymers | de |
dc.subject.eng | Spider Dragline Silk | de |
dc.subject.eng | RAFT Polymerization | de |
dc.subject.eng | Mechanical Properties | de |
dc.identifier.urn | urn:nbn:de:gbv:7-11858/00-1735-0000-002B-7CD8-0-6 | |
dc.affiliation.institute | Fakultät für Chemie | de |
dc.subject.gokfull | Chemie (PPN62138352X) | de |
dc.identifier.ppn | 874847885 | |