| Abstract
| - Spherical micelles of a polystyrene-b-poly(dimethylsiloxane) (PS-b-PDMS) diblock copolymer with thenumber-average molecular weight of 193 000 g/mol for PS and 39 000 g/mol for PDMS were obtained byusing n-dodecane or n-octane as the selective solvent for the PDMS block. The drying process of micellesolution drops with relatively high polymer concentration on solid substrates and the resultant dryingpatterns were studied using optical microscopy and atomic force microscopy. The drying drops exhibitedan inner solution “cap” connecting with an outer gelled “foot” through a transition zone. A crust was firstformed on the surface of the transition zone and remained on the top of the foot region. An inhomogeneousstress perpendicular to the radial direction within the crust, which was due to the solvent evaporationaccompanied by the receding of the solution cap, induced regular 45°-tilted stripes (pleats) in the transitionzone and main radial cracks in the foot region. The stripes and cracks have periods of a few and tens ofmicrons, respectively. Concave micelle “bricks” were also observed between cracks. In addition to micelleclose packing, these patterns demonstrate that drying micelle solution drops may provide a potentialmeans to manipulate fine and multiscale structures for technological applications.
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