title: Three-dimensional block copolymer nanostructures by the solvent-annealing-induced wetting in anodic aluminum oxide templates.
abstract: Block copolymers have been extensively studied over the last few decades because they can self-assemble into well-ordered nanoscale structures. The morphologies of block copolymers in confined geometries, however, are still not fully understood. In this work, the fabrication and morphologies of three-dimensional polystyrene-block-polydimethylsiloxane (PS-b-PDMS) nanostructures confined in the nanopores of anodic aluminum oxide (AAO) templates are studied. It is discovered that the block copolymers can wet the nanopores using a novel solvent-annealing-induced nanowetting in templates (SAINT) method. The unique advantage of this method is that the problem of thermal degradation can be avoided. In addition, the morphologies of PS-b-PDMS nanostructures can be controlled by changing the wetting conditions. Different solvents are used as the annealing solvent, including toluene, hexane, and a co-solvent of toluene and hexane. When the block copolymer wets the nanopores in toluene vapors, a perpendicular morphology is observed. When the block copolymer wets the nanopores in co-solvent vapors (toluene/hexane = 3:2), unusual circular and helical morphologies are obtained. These three-dimensional nanostructures can serve as naontemplates for refilling with other functional materials, such as Au, Ag, ZnO, and TiO2 .
authors.affiliation: Department of Applied Chemistry, National Chiao Tung University, Hsinchu, Taiwan, 30050, Republic of China.
authors.forename: Chiang-Jui
authors.initials: CJ
authors.lastname: Chu
authors.forename: Pei-Yun
authors.initials: PY
authors.lastname: Chung
authors.forename: Mu-Huan
authors.initials: MH
authors.lastname: Chi
authors.forename: Yi-Huei
authors.initials: YH
authors.lastname: Kao
authors.forename: Jiun-Tai
authors.initials: JT
authors.lastname: Chen
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry*; D004129:Dimethylpolysiloxanes / Q000737:chemistry*; D004566:Electrodes; D006586:Hexanes / Q000737:chemistry; D018625:Microscopy, Atomic Force; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D058608:Nanopores / Q000648:ultrastructure; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D011108:Polymers / Q000737:chemistry*; D011137:Polystyrenes / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry*; D014050:Toluene / Q000737:chemistry; D017155:Wettability
chemical_list: D004129:Dimethylpolysiloxanes; D006586:Hexanes; D011108:Polymers; D011137:Polystyrenes; D012997:Solvents; D014050:Toluene; C013830:baysilon; D000537:Aluminum Oxide
keywords: block copolymers; self-assembly; solvent annealing; template; wetting