| 초록 |
The orientations of block copolymer thin films were studied on phenylalkyl self-assembled monolayer (SAM) deposited substrates. Two different phenylalkylsiloxane self-assembled monolayers, from phenylethyltrichlorosilane (PETS) and phenylundecyltrichlorosilane (PUTS), were deposited on Si wafers. Then, Polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) with lamellar and cylindrical structure were spin-coated on PETS and PUTS deposited substrates and annealed at 180℃ in vacuum. To characterize the SAMs dynamic contact angle measurement and Near Edge X-ray Absorption Fine Structure were used and orientations of block copolymer films were investigated on the basis of Atomic Force Microscope (AFM). It is interesting to note that the orientations were changed from parallel to perpendicular depending on molecular weights of block copolymers. Parallel orientation was formed when the molecular weight of PS-b-PMMA was relatively small, in contrast, perpendicular orientation was occurred on relatively high molecular weights PS-b-PMMA for both lamellar and cylindrical block copolymers. In particular, perpendicular domains lasted longer on PUTS SAM which had longer alkyl chains than on PETS SAM. Based on these results, the structure of SAM affects the orientation of block copolymers and the molecular weight or degree of polymerization is important to determine the orientation of block copolymer thin films as well as surface morphology. |
