Porous films from cyclic block copolymers

Abstract

Porous films are attractive materials used in numerous fields, such as catalysis, templating, and separation. In previous examples of porous films prepared from block polymers, the pore size was usually determined by various factors, including mutual interaction between polymer chains, and was hard to precisely manipulate by modification of the block polymers. Herein, we report a novel method of preparing porous films from cyclic block copolymers with the pore size determined by the size of individual components. The incompatibility of the dangling polystyrene arms and cyclic polysiloxane backbones drove the assembly, which then led to the vertical alignment of the cyclic polysiloxane backbone to form porous films. Coarse-grained molecular dynamics simulations were also implemented to gain insight into the assembly process and the film microstructure at the molecular scale. A cyclic block copolymer allows feasible fabrication of porous films through designed interaction between its macromolecular arms. The morphology of pores is directly determined by the structural features of the block copolymer and can be easily tuned by modification of the length of its ring and arms.