Flow and conductivity properties of comb-shaped self-organized supramolecules

Abstract

Structures, which are significantly smaller than e.g. in the present day microelectronics, are pursued in nanotechnology. Structures near molecular level can be constructed for example by imitating biological systems where self-organization and molecular recognition are used to form supramolecules.

In this work hierarchically self-organized supramolecular nanostructured materials are constructed with peculiar conductivity behavior. The structures are, as such, not macroscopically aligned and therefore the conductivity is isotropic throughout the macroscopic sample.

Two types of supramolecular materials are studied under an oscillatory shear flow in order to find routes towards macroscopically oriented hierarchical structures. The first type consists of 20 - 50 Å lamellar structure due to self-organization of comb-shaped supramolecules. The second structure is a hierarchically self-organized, i.e. lamellar-within-lamellar structure, where there are structures at two length scales, i.e. at 20 - 50 Å and 200 - 1000 Å. Shear flow conditions allowing optimal macroscopic order were identified. Finally, macroscopically aligned protonically conducting material is presented, which shows globally tridirectional conductivity with anisotropic hopping conductivity.

Asymmetric structures i.e. lamellae-within-cylinders are also briefly studied and a method is found to achieve mesoporous materials with polymer brushes at the walls of emptied cylinders. The brushes can be used to tailor the functionalities of the pores.

The results of this work show that materials, which are relatively simple to produce, allow tailored macroscopic properties due to their aligned self-organized nanoscale structures.