Supramolecular assembly of functionalized polymers : straightforward synthesis and dynamic investigations of individual nanostructures

摘要

Understanding self-assembly of matter on the nanometer scale is crucial in modern materials’ science to increase the control over novel properties such as responsiveness and reversibility for, e.g., self-healing or stimuli-repsonive materials. The results shown in this thesis discuss the use of difunctional initiators in nitroxide-mediated polymerization for the one-step preparation of telechelic polymers with supramolecular bondings sites – namely 2-ureido-4[1H]-pyrimidinone as hydrogen bonding and 2,2’:6’,2‘’-terpyridine as metal complexing moieties – and its use for defined self-assembly towards responsive and amphiphilic linear suprapolymers. The approach is suitable to easily adjust the polymeric spacer between the supramolecular binding sites to optimize features such as reversibility for efficient responsive architectures. Since supramolecular assembly is also driven by self-assembly of covalently bonded block copolymer segments, ABC triblock oxazolines containing fluorophilic block were investigated by cryoTEM investigations showing unique examples of the coexistence of lamellar and bicontinuous phases in transient structures in solution. However, hierarchical or dynamic processes of these supramolecular assemblies can not be characterized by the static nature of cryoTEM. The introduction of ionic liquids as liquid media in TEM enables for the first time with low preparative efforts the possibility to investigate dynamic processes of individual supramolecular assemblies on the nanometer scale. For example, the motion of block copolymer assemblies were investigated in-situ revealing individual motion of the particles in the free-standing ionic liquid films. Also dynamic processes of assemblies of block copolymer containing insoluble blocks with low glass transition temperatures were observed in situ showing deformations, e.g. membrane fission of vesicles, upon beam irradiation.