The topics of this thesis are self-organized templates, hierarchical structure-within-structure morphologies and induced chirality in solid state assemblies of dendritic molecules. They all contribute to our understanding of the mechanisms of structure formation in the nano- and mesoscale which is key to new materials with unparalleled properties and adaptive functionalities. In Publications I and II, the microphase separation of diblock copolymers is utilized to template a novolac-type resin to obtain porous carbonaceous material or flakes depending on the initial amount of resin in the mixture. The porous material readily exhibits mesoscale pores which enhance mass transportation while the amount of micropores and thus the total surface area can be controlled by pyrolyzation time. The flakes have high aspect ratio and may have either a solid surface or be covered by polymer brushes ("hairy" flakes) depending on the preparation method. In Publications III and IV, a second level of structural order is achieved by introducing side-chains to a diblock copolymer. These structures are studied in fixed lamellar morphology on the block copolymer level in bulk and in submicrometer particles. With low side-chain content, side-chains form a single layer sandwiched in the middle of the side-chain block lamellae. This structure changes gradually to liquid crystalline smectic layers ordered perpendicularly to the block domain interfaces as the side-chain content is increased. In the particles, the lamellae form an onion-like morphology except for the high side-chain content block copolymer where the onion-like structure breaks down due to increased splay deformation energy. Publication V explores the induction of chirality in solid state. Addition of chiral side-chains to three generations of three different types of dendritic molecules leads to nine homologous supramolecules. Structural and optical studies on these cases reveal that the final structures are indeed chiral and that the "strength" of the chirality depends on the quality of the structures. The low generation supramolecules with simpler structures result in better ordered and optically higher-quality morphologies than the higher generation and more complex molecules.
|Translated title of the contribution||Lohkopolymeerien ja dendristen molekyylien nano- ja mesoskaalan rakenteiden ohjaaminen|
|Publication status||Published - 2013|
|MoE publication type||G5 Doctoral dissertation (article)|
- induced chirality
- block copolymer
- dendronized polymer