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Item type:Item, Formation of honeycomb structures and superhydrophobic surfaces by casting a block copolymer from selective solvent mixtures(2007-02-02) ;Tung, Pao-Hsiang ;Kuo, Shiao-Wei ;Jeong, Kwang-Un ;Cheng, Stephen Z. D.Huang, Chih-FengPoly(vinyl phE!nol)-block-polystyrene (PVPh-b-PS) diblock copolymers are synthesized by sequential anionic polymerization with sec-butyl lithium as the initiator. The Pvph-b-PS diblock copolymer is cast (on a substrate) from several solvent mixtures that contain tetrahydrofuran/toluene ratios of 1:0.1, 1:1, and 1:2. After solvent evaporation the resulting films are characterized by SEM, TEM, and contact angle measurements. A honeycomb structure is fabricated from the vesicle structure at relatively low toluene contents. On the contrary, at relatively higIier toluene contents, a micelle structure with porous microspheres is formed, which possesses higher surface roughness and results in film surface superhydrophobicity. The simple method described here that uses common/selective mixed solvents may be easily extended to prepare honeycomb structures and superhydrophobic surfaces simultaneously from a wide variety of block copolymers by carefully controlling the weight composition of the block copolymer and the selective solvent con-tent.Item type:Item, Micellization and the surface hydrophobicity of amphiphilic poly(vinylphenol)-block-polystyrene block copolymers(2007-08-20) ;Tung, Pao-Hsaing ;Kuo, Shiao-Wei ;Chan, Shih-Chien ;Hsu, Chih-HaoWang, Chih-FengThe self-assembly of PVPh-b-PS in different solvents was studied. Upon replacing toluene by THF as the solvent, the morphology of the resulting aggregates change from core-shell spheres, rod-like micelles and vesicles to onion-like aggregates. With increasing block copolymer concentration, morphologies such as honeycomb-like films, surfaces of aggregated large porous spheres, or pincushion-like spheres with protruding tubular vesicle aggregates are observed. These surface-patterned films show significantly enhanced hydrophobicity. The results suggest that a superhydrophobic . behavior can be achieved, with a maximum contact angle of 158 degrees, by using the pincushion-like micellar structure.