Hierarchical Structures of P(S-b-4VP) Thin Films Fabricated through a Combination of Solvent Annealing and Micro-Contact Imprinting

• Main Authors: Yu-chi Lee, 李育綺
• Other Authors: Ya-sen Sun
• Format: Others
• Language: en_US
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/06166868193019889726

博士 === 國立中央大學 === 化學工程與材料工程研究所 === 100 === We studied the self-assembly of block copolymer thin films with a combination of micro-contact imprinting and solvent annealing. Patterned substrates were prepared by selectively grafting PS chains on SiOx/Si by micro-contact imprinting. The PS-grafted regions have a hexagonal array on SiOx/Si. After spin coating on the patterned substrates, the block copolymer would selectively wet the PS-grafted regions with solvent vapor exposure. Therefore, solvent annealing causes dewetting-induced microdroplets with a microscopic order defined by the pattern of PS-grafted substrates. In this thesis, we investigated how relief polystyrene-block-poly(4-vinylpyridine), (P(S-b-4VP)) microstructures effected the internal nanostructures and microscopic shape on PS-patterned substrates in response to the solvent vapor selectivity. Upon annealing in THF vapor, the droplets comprised of nanospheres and the shape of each droplet is hemispherical cap. Solvent annealing in chloroform and acetone vapors led to terraced stack of lamellae. Each lamellar layer has the thickness of an entire PS-P4VP/P4VP-PS layer. In a dynamic process of DMF vapor annealing, the droplets would transform into three types of microstructures. They are nanosphere-comprised terraces, nanolamella-comprised terraces and nanocylinder-comprised droplets. For DMF annealed terraces, lamellar layers comprise PS-P4VP layer indicated that the thickness of PS-P4VP layer is half of the thickness of an entire PS-P4VP/P4VP-PS layer. The changes in nanoscale and microscale structures are due to the adaption of stimuli-responsive polymer materials to the free surface under the confinement of the patterned substrates. Finally, the movement of relief microstructures on a 30°-inclined patterned substrate was found to depend on the solvent solubility and internal nanostructures.