Kinetic pathways of gyroid-to-cylinder transitions in diblock copolymers under external fields: cell dynamics...

Using cell dynamics simulation we investigate the cubic gyroid morphology of block copolymer melts under simple shear flow and electric field. The electric field should be stronger than a certain critical value to induce transition to a cylindrical phase. In the case of simple steady shear the gyroid-to-cylinder transition was observed even for a very weak shear. Quantitative analysis of pathways of gyroid-to-cylinder transition is performed by means of Minkowski functionals. We found that the kinetics of the gyroid-to-cylinder transition are different under electric field and shear flow. Moreover, the gyroid structure under different strengths of electric field shows different pathways. Different types of intermediates such as five-, four-fold connections and "winding" cylinders are found for different pathways.