Browsing by Author "Yao, I-Chun"

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Block Copolymer Micelle Nanotubes by the Solvent-Annealing-Induced Nanowetting in Anodic Aluminum Oxide Templates
(2015-11-01)
Yao, I-Chun
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Cheng, Ming-Hsiang
;
Chen, Jiun-Tai
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應用化學系
;
Department of Applied Chemistry
Block copolymer micelles are generally formed by the self-assembly of amphiphilic copolymer molecules in aqueous medium. Although different types of block copolymer micelles have been studied, the self-assembly behavior of block copolymer micelles in confined geometries have been rarely studied. In this work, the fabrication of polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) micelle nanotubes in the cylindrical nanopores of anodic aluminum oxide templates using a solvent-annealing-assisted wetting method is presented. The PS-b-P4VP chains wet the pore walls in the form of micelles when the sample is annealed in the vapor of toluene, a good solvent for PS and a nonsolvent for P4VP. The formation of the PS-b-P4VP micelle nanotubes instead of nanorods implies that the micelles wet the nanopores in the complete wetting regime. This study not only contributes to a deeper understanding of the self-assembly behavior of block polymer micelles in confined geometries, but also provides more possible variations and design freedoms in the application of block copolymer micelles.
Block copolymer micelles confined in cylindrical nanopores: Effects of annealing solvents and hybridization
(2020-05-01)
Cheng, Ming-Hsiang
;
Yao, I-Chun
;
Chiu, Tang-Yao
;
Chen, Jiun-Tai
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交大名義發表
Amphiphilic block copolymer micelles have been intensively investigated and applied into various research fields for decades. One of the most promising characteristics for block copolymer micelles is the selective incorporation of metal precursors in the cores or coronas of the micelles. By combining with nanoporous membranes, aligned polymer nanostructures can be generated, facilitating the applications such as nanolithography and catalysis. The morphology transitions and controllability of block copolymer micelles in confined geometries, however, have seldom been studied. In addition, for hybrid micelles in which polymer segments are selectively incorporated with inorganic metal precursors, the relationship between hybridization and morphologies of polymer nanostructures in the confined states is still under discussion. In this work, we investigate the effects of annealing solvents and hybridization with metal precursors (gold(III) chloride trihydrate (HAuCl4 center dot 3H(2)O)) on the morphologies of polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) block copolymer micelles confined in the nanopores of anodic aluminum oxide (AAO) templates. Tuned by the annealing solvent vapors and the selective ion complexation between HAuCl4 and P4VP cores, various morphologies can be effectively controlled, such as the spherical-micelles-in-rod morphology, the parallel-cylinders-in-rod morphology, and the hemispherical-micelles-in-rod morphology. This study not only investigates the effects of annealing solvent vapors and hybridization on the morphologies of block copolymer micelles confined in cylindrical nano-geometries but also offers a viable route for preparing metal nanoparticles embedded in porous templates.
Effect of Thermal Annealing on the Surface Properties of Electrospun Polymer Fibers
(2014-02-01)
Chen, Jiun-Tai
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Chen, Wan-Ling
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Fan, Ping-Wen
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Yao, I-Chun
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應用化學系
Electrospun polymer fibers are gaining importance because of their unique properties and applications in areas such as drug delivery, catalysis, or tissue engineering. Most studies to control the morphology and properties of electrospun polymer fibers focus on changing the electrospinning conditions. The effects of post-treatment processes on the morphology and properties of electrospun polymer fibers, however, are little studied. Here, the effect of thermal annealing on the surface properties of electrospun polymer fibers is investigated. Poly(methyl methacrylate) and polystyrene fibers are fist prepared by electrospinning, followed by thermal annealing processes. Upon thermal annealing, the surface roughness of the electrospun polymer fibers decreases. The driving force of the smoothing process is the minimization of the interfacial energy between polymer fibers and air. The water contact angles of the annealed polymer fibers also decrease with the annealing time.
Rapid separation of gold nanorods in multilayer aqueous systems via centrifugation
(2016-01-01)
Yao, I-Chun
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Chang, Chun-Wei
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Ko, Hao-Wen
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Li, Heng
;
Lu, Tien-Chang
In this work, we demonstrate multilayer aqueous systems as media to separate gold nanoparticles of different shapes and sizes. The multilayer aqueous systems are composed of CTAB/EG solutions with different viscosities. By centrifugation, gold nanoparticles with different shapes and sizes can be dispersed in different layers of the aqueous systems. Gold nanorods synthesized by different conditions, such as changing the amount of AgNO3 or different aging times, are used to examine the multilayer aqueous systems. Gold nanorods with higher aspect ratios can be obtained by increasing the concentration of AgNO3, as confirmed by UV-Vis spectra and TEM studies. The separated gold nanorods are also characterized by surface-enhanced Raman scattering (SERS), showing lower activity for gold nanorods with higher aspect ratios, due to the size-dependent absorption of the longitudinal plasmon band. The multilayer aqueous systems can effectively separate gold nanorods prepared by different conditions and can be applied to separate other types of nanoparticles.
Solvent-Annealing-Induced Nanowetting in Templates: Towards Tailored Polymer Nanostructures
(2013-02-25)
Chen, Jiun-Tai
;
Lee, Chih-Wei
;
Chi, Mu-Huan
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Yao, I-Chun
;
應用化學系
We study the solvent-annealing-induced nanowetting in templates using porous anodic aluminum oxide membranes. The morphology of polystyrene and poly(methyl methacrylate) nanostructures can be controlled, depending on whether the swollen polymers are in the partial or complete wetting regimes, which are characterized by the spreading coefficient. When the swollen polymers are in the partial wetting regime, polymers wet the nanopores by capillary action, resulting in the formation of polymer nanorods. When the swollen polymers are in the complete wetting regime, polymers form wetting layers in the nanopores, resulting in the formation of polymer nanotubes. The solubility parameters of polymers and solvents are also used to predict the wetting behavior of swollen polymers in cylindrical geometry.