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dc.contributor.advisor Vana, Philipp Prof. Dr.
dc.contributor.author Hendrich, Katharina
dc.date.accessioned 2020-03-04T10:53:51Z
dc.date.available 2020-03-04T10:53:51Z
dc.date.issued 2020-03-04
dc.identifier.uri http://hdl.handle.net/21.11130/00-1735-0000-0005-134A-3
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 Smart RAFT-Polymer Surfaces: Exploring their Self-assembly and Dynamics on the Nanoscale de
dc.type doctoralThesis de
dc.contributor.referee Vana, Philipp Prof. Dr.
dc.date.examination 2020-02-11
dc.description.abstracteng Synthetic polymers on surfaces are excellent models to mimic biological systems which are highly sophisticated in their responsive behaviour to environmental changes. To expand the application possibilities of smart polymer surfaces as modern devices like sensors, microfluidic channels or even next-generation computer chips, the development of new surface analyzing techniques is required. In the context of this thesis, tethered polymers were synthesized and comprehensively analyzed using metal induced energy transfer (MIET) to establish this technique in polymeric surface science. With the gained insight of surface-tethered polymers, the generation of nanostructures mediated by constrained dewetting of homopolymers was investigated. MIET is a novel method that allows for the measurement of accurate distances at the scale of macromolecular systems using fluorescence lifetime imaging. This technique offers the possibility to investigate single molecules attached to a silicon dioxide spacer on a thin gold layer. To exploit this potential, the preparation of structurally well-defined polymer chains is indispensable. Using reversible addition-fragmentation chain transfer (RAFT) polymerization, the goal of synthesizing immobilized polymer chains of desired grafting density, molar mass and end-group functionalization could be accomplished. Specifically, by the thorough investigation of different reaction conditions, optimum polymerization parameters were established to prepare MIET substrates with tethered poly(2-(dimethylamino)ethyl prop-2-enoate) (p(DMAEMA)), a pH-responsive polymer. This achievement provided the basis for exploring the scope of MIET in collaboration with the Enderlein group (Third Institute of Physics, University Göttingen). For the first time, MIET measurements could successfully be conducted for polymer layers with grafting densities that range from individual tethered chains to high density polymer brushes. It was observed, that the layer thickness increases with increasing grafting density, which is in agreement with theoretical descriptions known from the literature. In order to explore the range of applicability of the MIET technique, p(DMAEMA) was exposed to aqueous solutions at different pH values and measurements were performed to investigate the responsive polymer properties. Here, monitoring of repulsive segment-segment interactions for small grafting densities and additional repulsive interactions between adjacent polymer chains was achieved. The results of the MIET measurements were also confirmed by spectroscopic ellipsometry. Within the second project of this thesis, it could be demonstrated that only a few tethered homopolymer chains are required to generate tailored nanostructured surfaces. The systems of choice were linear and four-arm star polystyrene samples prepared by RAFT polymerization on gold substrates. Without activation or chemical modification of the gold substrate, polymeric molecules of both architectures could be immobilized only via their sulfur-containing RAFT group. Subsequently, by means of an optimized dewetting technique, a variety of spherical and worm-like micelles as well as network structures were obtained. The nanostructures were specifically tuned by the adjustment of different grafting densities and the solvent quality during the dewetting procedure. As the visual evaluation of the formed morphologies can be misleading, a strategy to quantitatively analyze the differently shaped domains was developed. An unambiguous characterization was achieved using Minkowski quantities and completed by the specification of the obtained domains through calculation of circularities. Furthermore, the assembly of gold nanoparticles on planar gold substrates featuring polystyrene layers. Gold nanoparticles stabilized in aqueous solution could be precisely arranged within a preformed polymeric nanostructure. The latter prevented the uncontrolled aggregation of the gold nanoparticles, and instead mediated the formation of a dense nanoparticle monolayer. In contrast, the immersion of uniform polystyrene layers in dispersions of gold nanoparticles in toluene yielded multicomponent aggregates of tunable size, which could be controlled by the number of tethered polymer molecules. de
dc.contributor.coReferee Müller, Marcus Prof. Dr.
dc.subject.eng Nanoscale Materials de
dc.subject.eng RAFT-Polymerization de
dc.subject.eng Fluorescence Microscopy de
dc.subject.eng Metal-induced Energy Transfer de
dc.identifier.urn urn:nbn:de:gbv:7-21.11130/00-1735-0000-0005-134A-3-8
dc.affiliation.institute Fakultät für Chemie de
dc.subject.gokfull Chemie  (PPN62138352X) de
dc.identifier.ppn 1691728608

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