In situ grazing incidence small‐angle X‐ray scattering study of solvent vapor annealing in lamellae‐forming block copolymer thin films: Trade‐off of defects in deswelling

Abstract

ABSTRACTSolvent vapor annealing (SVA) is one route to prepare block copolymer (BCP) thin films with long‐range lateral ordering. The lattice defects in the spin‐coated BCP thin film can be effectively and rapidly reduced using SVA. The solvent evaporation after annealing was shown to have a significant impact on the in‐plane ordering of BCP microdomains. However, the effect of solvent evaporation on the out‐of‐plane defects in BCPs has not been considered. Using grazing‐incidence x‐ray scattering, the morphology evolution of lamellae‐forming poly(2‐vinlypyridine)‐b‐polystyrene‐b‐poly(2vinylpyridine) triblock copolymers, having lamellar microdomains oriented normal to substrate surface during SVA, was studied in this work. A micelle to lamellae transformation was observed during solvent uptake. The influence of solvent swelling ratio and solvent removal rate on both the in‐plane and out‐of‐plane defect density was studied. It shows that there is a trade‐off between the in‐plane and out‐of‐plane defect densities during solvent evaporation. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017, 55, 980–989