| 초록 |
It is well known that the structure of symmetric diblock copolymer thin films is governed by boundary conditions, i.e. commensurability and interfacial interactions. For unconfined films having lamellar morphology, film thickness is quantized to nL0 (where n is an integer and L0 is the bulk equilibrium lamellar period) in case of symmetric wetting or (n+1/2)L0 in case of asymmetric wetting. If the initial film thickness is not commensurate with this constraint, either holes or islands of height L0 are formed. In our previous works, the formation of unusual hierarchical micropatterns was observed at low spinning speed and was inferred to occur by residual solvent in thin films. In order to investigate the role of residual solvent, symmetric poly(styrene-b-methyl methacrylate) (PS-b-PMMA) block copolymer thin films were prepared from various solvents, i.e. chloroform, xylene, dichlorobenzene, which have different boiling temperatures. After annealed above glass transition temperature, intriguing surface morphology of thin films was observed by both optical microscopy and atomic force microscopy. |
