Browsing by Author "Wu, Ren-Jye"

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Copolymer and platinum ion assisted growth of functionalized gold nanonests
(2015-01-01)
Yang, Jing-Cyuan
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Chang, Yi-Hsiang
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Whang, Wha-Tzong
;
Chen, Chun-Hua
;
Wu, Ren-Jye
This paper describes a facile low-toxicity synthesis of two different types of Au nanonests and one binary Au-Pt core-shell nanonest with high yield and excellent uniformity in size and morphology using block copolymer P123 (EO20PO70EO20) as a soft template and the main reductant in an ice water bath. The introduction of a suitable second metallic source, i.e. Pt ions in the present case, was proven to be a unique strategy for effectively governing the reduction sites of P123 for Au nucleation, which leads to significant changes especially in the crystallite size of the grown Au nanonests. The Au nanonests exhibited a distinct morphology-dependent surface plasmon resonance (SPR) that is red-shifted by similar to 140 nm from the spherical particles wavelength, and significant surface-enhanced Raman scattering (SERS), allowing the rapid determination of rare malachite green oxalate (MGO).
Effect of Ionic Liquid on Structure and Properties of Polysquaraines
(2012-04-10)
Ho, Mei-Chan
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Chao, Ching-Hsun
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Chen, Chun-Hua
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Wu, Ren-Jye
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Whang, Wha-Tzong
Polycondensation of 4-bis[2-(1-methylpyrrol-2-yl)vinyl]-2,5-didodecyloxybenzene and squaric acid yielded the polysquaraine SQ with two isomeric subunits-1,3-addition (zwitterionic) and 1,2-addition (diketonic) moieties in the main chain structure. The former featured a C-O/C=O infrared (IR) absorption frequency at 1622 cm(-1); the latter, a C=O signal at 1716 cm(-1). Traditional synthesis yielded SQ as a powder with metallic luster that could not be cast as a polymer film from solution. When the ionic liquid [Oct(3)NMe][TfO] (IL) was present in the cosolvent of BuOH and benzene (1:3), however, the resulting SQI(x) polymers (x = 0.01-5 wt %) did not precipitate from solution, making it possible to cast continuous free-standing films with a large area (>1 X 1 cm(2)). A greater content of IL in the solution favored the formation of the 1,3-addition zwitterionic subunits in the SQI(x) polymer main chains, thereby changing the physical and optical properties of the polysquaraine, as evidenced in IR and optical absorption spectra. The features in the UV-Vis-NIR absorption spectra of SQ and SQL(x) were dependent on the IL concentration and the nature of the solvent. Among our synthesized SQI(x) polymers, SQI(0.01) and SQI(0.1) formed flexible free-standing films with metallic luster, smooth surfaces, and good semiconductivities (2.27 x 10(-5) and 4.74 x 10(-5) S/cm, respectively). X-ray diffraction patterns revealed that the presence of IL in the polymerization medium increased the SQI(x) interchain packing distance. SQI(0.01), and SQI(0.1) possessed thermal stabilities comparable with that of SQ. Our successful use of IL in the preparation of SQI(x) polymers appears to have great potential for application in ionic liquid-related organic or polymeric preparation and processing.
Facile growth of silver crystals with greatly varied morphologies by PEO-PPO-PEO tri-block copolymers
(2012)
Yang, Jing-Cyuan
;
Chen, Chun-Hua
;
Wu, Ren-Jye
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材料科學與工程學系
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Department of Materials Science and Engineering
Silver crystals with various novel nano-scale morphologies were synthesized from the reduction of silver nitrate (AgNO3) by ascorbic acid (AsA) in aqueous PEO-PPO-PEO tri-block copolymer (F127) solutions. The presence of only high-concentration AsA at the very initial stage of reduction acts as a key factor in forming distinct branched quasi-spherical Ag nanocrystals where coral-like and houseleek-like morphologies can be kinetically controlled via subsequent addition of F127. When AsA and F127 were mixed before the reduction, three-dimensional dendritic Ag nanocrystals with highly ordered dendrites were largely obtained. In contrast to these branched crystals prepared under low F127 concentration, the face-centered cubic (FCC) packed micelles at high F127 concentration, which provided orderly reaction spaces for AgNO3 and AsA reagents, dominated the growth of triangular and hexagonal prisms. The great variety in morphology is directly correlated with not only the concentration ratio between these reactants but the F127 induced kinetic mechanisms. Moreover, the greatly branched Ag nanocrystals exhibit significant surface-enhanced Raman scattering (SERS) for facilely, rapidly and effectively determining malachite green oxalate (MG) in aqueous solution. The present results provide valuable data not only for fundamental understanding of the directing effect of both F127 and AsA on the synthesis of Ag nanocrystals, but for advanced design and practical manufacturing of metals enhanced SERS sensors.
Pt-Pd Floating Nanoarrays Templated on Pluronic F127 Micelles as Effective Surface-Enhanced Raman Scattering Sensors
(2019-04-01)
Chang, Fang-Ching
;
Li, Yen-Cheng
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Wu, Ren-Jye
;
Chen, Chun-Hua
;
材料科學與工程學系
An innovative concept of floating nanoarrays (FNAs) as promising new-generation surface-enhanced Raman scattering (SERS) sensors was proposed for the first time and has been successfully realized via a facile triblock-copolymer-assisted chemical route. At least two categories of the complicated highly uniform Pt-Pd FNAs with a fairly small assembled diameter of less than 100 nm respectively consisted of quasi-orderly assembled spherical and petal-like nanocrystals with unique radially distributed compositions were evidently classified and reproducibly fabricated. The synthesized Pt-Pd FNAs were found to exhibit unusually strong surface plasmon resonance bands in the visible region and have been successfully demonstrated as practical SERS sensors with remarkably low analytical limits of detection.
Significant improvement in the thermoelectric properties of zwitterionic polysquaraine composite films
(2013-09-16)
Ho, Mei-Chan
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Chao, Ching-Hsun
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Lo, An-Ya
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Chen, Chun-Hua
;
Wu, Ren-Jye
In this study, the polysquaraine SQI(0.1), a zwitterionic pi-conjugated polymer, was adopted as the matrix for the preparation of flexible and freestanding films; the low band gap of this semiconducting polymer made it a natural choice for use as a thermoelectric (TE) polymer. To enhance their TE applications, both single-walled carbon nanotubes (SWNTs) and mesoporous carbon (i.e., CMK-3) were integrated into the SQI(0.1)-based films and the effects of doping with iodine were also investigated. Using scanning electron microscopy, the variations in morphology of these SQI(0.1)-based films were examined. Raman spectroscopy was used to study the pi-pi interactions between iodine and the carbon materials (Le., SWNT, CMK-3); X-ray diffraction and Raman spectroscopy to investigate the intercalation of the doped iodine in the composite films; and X-ray photoelectron spectroscopy to determine the valence state of the doped iodine. The TE properties of these materials were characterized in terms of the electrical conductivity (sigma), thermal conductivity (kappa), and Seebeck coefficient (S). The TE properties of the iodine-doped composite film prepared from SWNTs, CMK-3, and SQI(0.1) included a notable value of ZT (Figure of Merit) of 4.563 x 10(-3), which was 143% of that of the corresponding iodine-doped SQI(0.1) film. (c) 2013 Elsevier B.V. All rights reserved.