Effect of the Primary Structure of Amphiphilic Block Copolymers on Their Surface Orientation

Abstract

The amphiphilic block copolymer, poly{2‐[2(2‐methoxyethoxy)ethoxy]ethyl acrylate}‐block‐polystyrene (PMEEEA‐b‐PS), is a well‐designed polymer that forms a microphase‐separated structure oriented perpendicular to the film surface via simple thermal annealing. However, the preferential segregation tendency of one component and the resulting wettability to water are unavoidable at the local conformational level. To achieve better control of the surface structure of the polymer film, we systematically examine the effect of the primary structure of PMEEEA‐b‐PS prepared by controlled radical polymerization on the surface orientation behavior of its film with respect to the thermal annealing temperature. The optimization of the chemical composition of the block copolymer enables a clearer surface orientation of both components through thermal annealing over a wide range of temperatures. Variation in the primary structure of the block copolymer results in different surface structures and changes in the wettability to water. The key to surface orientation is an appropriate balance between the surface segregation of one component and stability of the microphase‐separated structure of the block copolymer, which is controlled by the primary structure and thermal annealing. These findings serve as useful guidelines for the precise design of the surface structures for the development of functional polymers with minimal energy and resources.