PhD Ceremony - Anton Hofman - Hierarchical structure formation in supramolecular comb-shaped block copolymers
|When:||Fr 10-06-2016 14:30 - 15:30|
|Where:||Academy building RUG|
Because of their chain-like architecture, blends of chemically different homopolymers are generally known to phase separate, similar to mixtures of water and oil. In block copolymers, however, two (diblock) or more (multiblock) of such macromolecules are covalently linked to each other, thereby making it impossible to phase separate macroscopically. Indeed, phase separation of block copolymers is confined to the molecular level. By changing the molecular weight or the composition of the copolymer, phase separation of diblock copolymers leads to spontaneous formation of numerous ordered structures with sizes ranging from approximately 10 up to 100 nm. Examples include lamellar, cylindrical and spherical structures.
Increasing the complexity of the macromolecular architecture usually leads to a more complex phase behavior. Structures formed by multiblock copolymers have for instance been thoroughly studied by both experimentalists and theoreticians. Since their synthesis is rather challenging, alternative, less demanding approaches are required for real-life technological applications. Supramolecular chemistry is one of these methods. By combining linear diblock copolymers and small organic surface active molecules, comb-shaped copolymers can be prepared by simply mixing both compounds. This often leads to the formation of multiblock-like hierarchical structures, i.e. structures within another structure.
The work described in this thesis is focused on the synthesis and self-assembly of a new class of supramolecular materials, so-called double-comb diblock copolymers. Microphase separation of such complexes resulted in several new, unique hierarchical morphologies that were not observed in block copolymer-based materials before. In addition, the general observed phase behavior was found to be in excellent agreement with previously developed theoretical models.