A novel strategy for controlling the orientation of cylindrical domains in thin blend copolymer films via ‘double phase separation’

We discuss a simple and robust approach to control the orientation of cylindrical microdomains in block copolymer films. The approach is based on the so-called double phase separation occurring in the binary blend of incompatible compositionally asymmetric block copolymers and their selective adsorption on a homogeneous surface. As a proof-of-concept, we perform mesoscale simulations, using dynamic density functional theory and dissipative particle dynamics, and show that the target morphology with perpendicularly oriented cylinders can be thermodynamically stable for rather thick films when the intrinsic hexagonal period of the majority bulk phase is commensurate with the surface-induced pattern formed by the strongly adsorbed minority component.