Large-scale alignment of ABC block copolymer microdomains via solvent vapor treatment

We have studied the microdomain morphology of thin ABC triblock copolymer f ilms supported by a solid substrate. The films were exposed to various solv ent vapors, and the effect of the solvent removal speed on the resulting mo rphologies is investigated. Slow solvent extraction rates lead to a paralle l alignment of lamellar microphases within the plane of the film. On fast d rying, a perpendicular orientation of the lamellae is found. In the case of block copolymer samples with a highly anisotropic macroscopic shape, the m icrodomains can be aligned over large lateral areas. The results are discus sed in view of the mechanical strain fields present during the drying proce ss.