Solvent-induced crystallization of PS-b-PEO-b-PS block copolymer films

摘要

Solvent-induced crystallization and dewetting behaviors of polystyrene-b-poly (ethylene oxide)-b-polystyrene (PS-b-PEO-b-PS) block copolymer films deposited on three different substrates, silicon, mica, and carbon-coated mica have been studied by atomic force microscope (AFM). When the common solvent dichloromethane was used for annealing, the films on all three of the substrates exhibited dewetting behavior; the dendritic crystallization patterns were found in the dewetted regions for the films on silicon and mica substrates, while for the films on carbon-coated mica, no crystallization pattern appeared. According to the observation of the crystallization patterns formed in the films with different initial thicknesses, it is shown that the width of the dendritic branches decreases with the increase of film thickness and solvent annealing time. When the PS-selective solvent toluene was used for annealing, the dewetting process was absent, and the crystallization patterns were observed on the surface of the films on all three kinds of substrates.