Effect of structural anisotropy on the coarsening kinetics of diblock copolymer striped patterns

Abstract

We compare the time evolution of striped pattern correlation lengths for three different poly(styrene- b -methyl methacrylate) (PS-b-PMMA) diblock copolymer materials having comparable molecular diffusion rates. Striped patterns formed from cylindrical-phase materials coarsen with enhanced growth exponents and have reduced disclination diffusion activation energies as compared to striped patterns formed from smectic A lamellar-phase materials. The observed differences stem from distinct topological constraints in cylindrical (columnar) and lamellar (SmA) striped patterns. Cylindrical domains create a channel for layer breaking without molecule interdiffusion, facilitating an enhanced rate of pattern coarsening and reducing the disclination diffusion activation energy. © 2008 The American Physical Society.