Summary

Topological defects are omnipresent in nanostructured materials made of block copolymers, and can have a critical influence on mechanical or transport properties of the materials. The goal of this project is to explore and analyse ways to control the structure and distribution of such defects by numerical simulations on different scales. Specifically, we will investigate the effect of blending in small fractions of dopant molecules such as star copolymers, or dopant particles such as polymer-grafted colloids, which are designed such that they might promote defect formation and/or stabilize defects. We will study the influence of such dopant defects on the topological defects in the materials depending on the dopant structure and concentration, but also on the parameters of the self-assembly process such as the thermal history. The motivation for the project is two-fold: First, it will provide insight into the relation between ordering kinetics, molecular defects and topological defects in block copolymers, which is still poorly understood. Second, by selectively inducing defects, we hope to obtain control over the topological defect structure of the material.

We will investigate the stabilization mechanisms of the topological defects in detail and distinguish between equilibrium structures (i.e., defects that correspond to global minima in the free energy landscape) and kinetically arrested structures (local minima) that can also be manipulated by processing pathways.