Browsing by Author "Kuo, Shiao-Wei"

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A cross-linkable triphenylamine derivative as a hole injection/transporting material in organic light-emitting diodes
(2015-01-01)
Shih, Hsi-Kang
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Chu, Yu-Lin
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Chang, Feng-Chih
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Zhu, Chao-Yuan
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Kuo, Shiao-Wei
We have synthesized TPABZ, a new thermally cross-linkable triphenylamine derivative containing a benzoxazine functional group, for application in organic light-emitting diodes (OLEDs). We used differential scanning calorimetry, thermogravimetric analysis, UV-Vis spectroscopy, and cyclic voltammetry to investigate the thermal, physical, and electrochemical properties of TPABZ, which is readily polymerized, through ring-opening polymerization of its benzoxazine unit, upon heating at 220 degrees C for 30 min. The cured TPABZ (P-TPABZ) is suitable for use as a hole injection/transport material in OLEDs because it has an appropriate HOMO energy level (-5.16 eV) to form a stepwise energy ladder and a high LUMO energy level (-1.68 eV) with great potential for electron blocking. We fabricated multilayered OLEDs (ITO/TPABZ or P-TPABZ/NPB/Alq(3)/LiF/Al) through successive spin-coating and vacuum deposition processes; the device incorporating P-TPABZ exhibited good performance (EQE: 2.44%; LEmax: 8.42 cd A(-1); PEmax: 4.34 lm W-1).
A facile cosolvent/chelation method for the preparation of semi-crystalline CuCl2(ethylene glycol)/poly(3-hexylthiophene) complexes displaying specific luminescence properties
(2015-01-01)
Lu, Fang-Hsien
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Mohamed, Mohamed Gamal
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Liu, Tzeng-Feng
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Chao, Chuen-Guang
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Kuo, Shiao-Wei
Semi-crystalline CuCl2(ethylene glycol)/poly(3-hexylthiophene) complexes (CE-P3HT) with specific textures and self-assembled structures can be fabricated using a facile co-solvent/chelation method. The morphologies and self-assembled structures of these CE-P3HT complexes were dependent on the concentration of CuCl2(ethylene glycol) (CuCl(2)EG) in solution. Transmission electron microscopy (TEM) revealed the CE-P3HT sample comprising EG and numerous CuCl2/P3HT dots (C-P3HT dots) that originated from the P3HT main chains interacting with CuCl2 crystals; the average size of this C-P3HT dots was ca. 20 nm. Prior to formation of the solid state of CE-P3HT structures, the CE-P3HT complex in solution displayed a novel phenomenon: a specific luminescence property with an absorption energy gap of 3.71-4.46 eV. This quantum effect resulted from the chelates formed between the Cu2+ ions and the thioether units of the conjugated P3HT polymer.
A Hollow Microtubular Triazine- and Benzobisoxazole-Based Covalent Organic Framework Presenting Sponge-Like Shells That Functions as a High-Performance Supercapacitor
(2019-05-02)
El-Mahdy, Ahmed F. M.
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Hung, Ying-Hui
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Mansoure, Tharwat Hassan
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Yu, Hsiao-Hua
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Chen, Tao
In this paper we report the construction of a hollow microtubular triazine- and benzobisoxazole-based covalent organic framework (COF) presenting a sponge-like shell through a template-free [3+2] condensation of the planar molecules 2,4,6-tris(4-formylphenyl)triazine (TPT-3CHO) and 2,5-diaminohydroquinone dihydrochloride (DAHQ-2HCl). The synthesized COF exhibited extremely high crystallinity, a high surface area (ca. 1855m(2)g(-1)), and ultrahigh thermal stability. Interestingly, a time-dependent study of the formation of the hollow microtubular COF having a sponge-like shell revealed a transformation from initial ribbon-like crystallites into a hollow tubular structure, and confirmed that the hollow nature of the synthesized COF was controlled by inside-out Ostwald ripening, while the non-interaction of the crystallites on the outer surface was responsible for the sponge-like surface of the tubules. This COF exhibited significant supercapacitor performance: a high specific capacitance of 256Fg(-1) at a current density of 0.5Ag(-1), excellent cycling stability (98.8% capacitance retention over 1850cycles), and a high energy density of 43Whkg(-1). Such hollow structural COFs with sponge-like shells appear to have great potential for use as high-performance supercapacitors in energy storage applications.
A New Poly(amide urethane) Solid State Electrolyte Containing Supramolecular Structure
(2010-03-09)
Yen, Ying-Chieh
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Cheng, Chih-Chia
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Kuo, Shiao-Wei
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Chang, Feng-Chih
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應用化學系
A quenching method for the preparation of metal oxide-polythiophene composites having fiber structures
(2014-01-01)
Lu, Fang-Hsien
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Mohamed, Mohamed-Gamal
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Liu, Tzeng-Feng
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Chao, Chuen-Guang
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Dai, Lizong
In this study we developed a simple quenching method to fabricate metal oxide (CuO, ZnO, TiO2, Fe(OH) 3)polythiophene (PT) composites. By varying the metal oxide, PT, and rate of crystallization, we could control the fiber morphology in these composites. Four-probe-station analyses revealed that the conductivities of these metal oxide-PT composites ranged from 10(-5) to 10(-3) S cm(-1), higher than that of any species of metal oxide alone (from 10(-10) to 10(-7) S cm(-1)), because the fiber morphology behaved as an exceptional transmission factor for electrons. Moreover, these metal oxide-PT composites exhibited the characteristics of colloids, as well as high viscosity, suggesting that they could also be applied as coatings on silicon and glass substrates, and could provide the opportunity to form useful materials for large-scale gas sensors due to good flexibility and porosity. UV-vis spectroscopic analyses revealed variations in the energy level (>3.37 eV for ZnO) and confirmed the mechanism of the morphology change of the composite.
A Simple Route from Monomeric Nanofibers to Zinc Oxide/Zinc Sulfide Nanoparticle/Polymer Composites through the Combined Use of gamma-irradiation Polymerization, Gas/Solid Reaction and Thermal Decomposition
(2008-10-01)
Kuo, Shiao-Wei
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Chung, Yao-Chu
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Jeong, Kwang-Un
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Chang, Feng-Chih
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應用化學系
We report a simple route to hierarchical zinc oxide/zinc sulfide (ZnO/ZnS) nanoparticle/polymer nanofiber structures through self-assembly of zinc dimethacrylate (Zn(MA)(2)) in water/ethanol solution. The water clusters in formed around Zn(MA)(2) would undergo hydrogen-bonding interactions to create a supramolecular structure and then form the construction of three-dimensional nanofibers and random networks. These monomeric Zn(MA)(2) nanofibers are converted into ZnO or ZnS nanoparticle/polymer nanofiber composites through a combination of gamma-irradiated polymerizations and in situ thermal decomposition or H2S gas/solid reactions, respectively. The carboxylic ion groups of P-Zn(MA)(2) remained bonded to zinc ions on the particles' surfaces after thermal decomposition or the reaction with H2S. The compact polymer network prevented the ZnO or ZnS nanoparticles from aggregating to eliminate the defects. High-resolution transmission electron microscopes indicate that ZnO and ZnS particles are highly crystallized with a size of 3-7 nm. This is a simple approach to produce nanoparticle in polymer nanofibers. This preparation method can potentially be extended to other polymer matrices containing different metal ions.
A solvent-resistant azide-based hole injection/transporting conjugated polymer for fluorescent and phosphorescent light-emitting diodes
(2015-01-01)
Huang, Cheng-Wei
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Chang, Feng-Chih
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Chu, Yu-Lin
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Lai, Cheng-Chang
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Lin, Tzu-En
Interfacial mixing of polymers is a critical issue when attempting to improve the charge transport and stabilize the operation of solution-processed organic light-emitting diodes (OLEDs). Herein, we describe a simple methodology for overcoming interfacial mixing, based on the use of a photo-crosslinkable hole injection/transporting material (HITM). We synthesized a conjugated polymer, PTCAzide, bearing ready crosslinking ability and investigated its suitability for use as an HITM. Photo-crosslinking of the PTCAzide copolymer gave X-PTCAzide, which exhibited much higher thermal stability (the glass transition temperature increased by 21 K relative to that of PTCAzide), remarkable electrochemical stability, and excellent solvent-resistance, thereby expanding the operation time of corresponding electronic devices. Such a tris(8-hydroxy-quinolinato) aluminum-based trilayer device reached a maximum brightness of 52 971 cd m(-2), and the maximum luminance efficiency (LE) and power efficiency (eta E) are both higher than those of the corresponding device based on commercial PEDOT:PSS. In addition, a solution-processed phosphorescent OLED device incorporating X-PTCAzide also exhibited good performance (external quantum efficiency: 7.93%; LE: 29.6 cd A(-1); eta E: 14.3 lm W-1; maximum brightness: 34484 cd m(-2)). The efficient and simple photocrosslinking without adding an initiator could facilitate the fabrication process. Thus, PTCAzide appears to be a promising next-generation HITM for the development of highly efficient and inexpensive OLEDs. Its photo-crosslinkable nature allows improvements in morphological stability and hole injection/transporting ability, leading to more stable devices with better operation, without disrupting molecular packing or charge transport.
Association of poly(N-isopropylacrylamide) containing nucleobase multiple hydrogen bonding of adenine for DNA recognition
(2013-04-15)
Yang, Hsiu-Wen
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Chen, Jem-Kun
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Cheng, Chih-Chia
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Kuo, Shiao-Wei
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應用化學系
In this study we used the poly(N-isopropylacrylamide) (PNIPAAm) as a medium to generate PNIPAAm-adenine supramolecular complexes. A nucleobase-like hydrogen bonding (NLHB) between PNIPAAm and adenine was found that changed the morphology, crystalline structure, and temperature responsiveness of PNIPAAm microgels relatively to the adenine concentrations. With increasing the adenine concentration, the PNIPAAm-adenine supramolecular complexes gradually altered their morphologies from microgel particles to thin film structures and suppressed the thermodynamical coil-to-globule transition of PNIPAAm because of the NLHB existed between the PNIPAAm amide and ester groups and the adenine amide groups (C=O center dot center dot center dot H-N and N-H center dot center dot center dot N-R), verified by FTIR spectral analysis. NLHB was also diverse and extensive upon increasing the temperature; therefore, the thermoresponsive behavior of the complexes was altered with the NLBH intensity, evaluated by the inter-association equilibrium constant (K-a) above and below their LCST. Therefore, PNIPAAm can be as a medium to recognize adenine in various concentrations, which could potentially be applied in DNA recognition. (C) 2013 Elsevier B.V. All rights reserved.
Bio-Inspired Supramolecular Chemistry Provides Highly Concentrated Dispersions of Carbon Nanotubes in Polythiophene
(2016-06-01)
Lin, Yen-Ting
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Singh, Ranjodh
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Kuo, Shiao-Wei
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Ko, Fu-Hsiang
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材料科學與工程學系
In this paper we report the first observation, through X-ray diffraction, of noncovalent uracil-uracil (U-U) dimeric 7r-stacking interactions in carbon nanotube (CNT)-based supramolecular assemblies. The directionally oriented morphology determined using atomic force microscopy revealed highly organized behavior through pi-stacking of U moieties in a U-functionalized CNT derivative (CNT-U). We developed a dispersion system to investigate the bio-inspired interactions between an adenine (A)-terminated poly(3-adeninehexyl thiophene) (PAT) and CNT-U. These hybrid CNT-U/PAT materials interacted through pi-stacking and multiple hydrogen bonding between the U moieties of CNT-U and the A moieties of PAT. Most importantly, the U center dot center dot center dot A multiple hydrogen bonding interactions between CNT-U and PAT enhanced the dispersion of CNT-U in a high-polarity solvent (DMSO). The morphology of these hybrids, determined using transmission electron microscopy, featured grape-like PAT bundles wrapped around the CNT-U surface; this tight connection was responsible for the enhanced dispersion of CNT-U in DMSO.
Conducting Ag/oligothiophene complex pastes through a simple quenching/chelation method
(2014-08-14)
Lu, Fang-Hsien
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Chang, Feng-Chih
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Mohamed, Mohamed-Gamal
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Liu, Tzeng-Feng
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Chao, Chuen-Guang
This paper describes a simple and environmentally friendly approach-a facile, one-pot, quenching/ chelation method-for the fabrication of a silver paste in the form of Ag/oligothiophene complex composites. These Ag/oligothiophene complex composites possess excellent conductivities of 1.8 x 10(4) S cm(-1) in the bulk state and 6.08 x 10(2) S cm(-1) in the form of thin films. We have used X-ray diffraction (XRD). X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) to characterize the microstructures of these novel Ag/oligothiophene complex composites.
Conducting Ag/oligothiophene complex pastes through a simple quenching/chelation method
(2014-08-14)
Lu, Fang-Hsien
;
Chang, Feng-Chih
;
Mohamed, Mohamed-Gamal
;
Liu, Tzeng-Feng
;
Chao, Chuen-Guang
This paper describes a simple and environmentally friendly approach-a facile, one-pot, quenching/ chelation method-for the fabrication of a silver paste in the form of Ag/oligothiophene complex composites. These Ag/oligothiophene complex composites possess excellent conductivities of 1.8 x 10(4) S cm(-1) in the bulk state and 6.08 x 10(2) S cm(-1) in the form of thin films. We have used X-ray diffraction (XRD). X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) to characterize the microstructures of these novel Ag/oligothiophene complex composites.
Effect of an organically modified nanoclay on low-surface-energy materials of polybenzoxazine
(2008-07-16)
Fu, Huei-Kuan
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Huang, Chih-Feng
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Kuo, Shiao-Wei
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Lin, Han-Ching
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Yei, Ding-Ru
Novel low surface free energy materials of polybenzoxazine/organically modified silicate nanocomposites have been prepared and characterized. The CPC (cetylpyridinium chloride)/ claylo%/poly(3-phenyl-3,4-dihydro-2H-1,3-benzoxazine) (PP-a) material possesses an extremely low surface free energy (12.7 Mj. M-2) after 4 h curing at 200'C, which is even lower than that of poly(tetrafluoroethylene) (22.0 Mj. M-2) calculated on the basis of the threeliquid geometric method. X-Ray photoelectron spectroscopy (XPS) shows a higher silicon content on the surface of the nanocomposites than for an average composition, which implies that the clay is more preferentially enriched on the outermost layer. In addition, the glass transition temperature (Tg) of the polybenzoxazine (PP-a) in the nanocomposite is 22.6'C higher and its thermal decomposition temperature is also 31.5'C higher than the pure PP-a. This finding provides a simple way to prepare low surface energy and high thermal stability materials.
Effect of intermolecular hydrogen bonding on low-surface-energy material of poly(vinylphenol)
(2007-04-07)
Lin, Han-Ching
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Wang, Chih-Feng
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Kuo, Shiao-Wei
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Tung, Pao-Hsiang
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Huang, Chih-Feng
We discovered that poly(vinylphenol) (PVPh) possesses an extremely low surface energy (15.7 mJ/m(2)) after a simple thermal treatment procedure, even lower than that of poly(tetrafluoroethylene) ( 2.0 mJ/m(2)) calculated on the basis of the two-liquid geometric method. Infrared analyses indicate that the intermolecular hydrogen bonding of PVPh decreases by converting the hydroxyl group into a free hydroxyl and increasing intramolecular hydrogen bonding after thermal treatment. PVPh results in a lower surface energy because of the decrease of intermolecular hydrogen bonding between hydroxyl groups. In addition, we also compared surface energies of PVPh-co-PS (polystyrene) copolymers (random and block) and their corresponding blends. Again, these random copolymers possess a lower fraction of intermolecular hydrogen bonding and surface energy than the corresponding block copolymers or blends after similar thermal treatment. This finding provides a unique and easy method to prepare a low-surface-energy material through a simple thermal treatment procedure without using fluoro polymers or silicones.
Fabrication of superhydrophobic and superoleophilic polystyrene surfaces by a facile one-step method
(2007-12-03)
Tu, Cheng-Wei
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Tsai, Chia-Hua
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Wang, Chih-Feng
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Kuo, Shiao-Wei
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Chang, Feng-Chih
A facile one-step method has been developed to prepare both superhydrophobic and superoleophilic surfaces of polystyrene (PS) without any chemical modification. A rough film consisting of micro-bead and nano-fiber mixed structures is formed by spraying a PS solution onto a large area and any type of substrate. The mixed structures with such unique wettability properties can be used in oil/water separation and as oil sorbents.
Formation of honeycomb structures and superhydrophobic surfaces by casting a block copolymer from selective solvent mixtures
(2007-02-02)
Tung, Pao-Hsiang
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Kuo, Shiao-Wei
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Jeong, Kwang-Un
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Cheng, Stephen Z. D.
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Huang, Chih-Feng
Poly(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.
Functional Supramolecular Polypeptides Involving pi-pi Stacking and Strong Hydrogen-Bonding Interactions: A Conformation Study toward Carbon Nanotubes (CNTs) Dispersion
(2016-08-09)
Huang, Cheng-Wei
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Mohamed, Mohamed Gamal
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Zhu, Chao-Yuan
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Kuo, Shiao-Wei
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應用化學系
New supramolecular polypeptides have been prepared through simple ring-opening polymerization and "click" reactions. Postfunctionalization with diaminopyridine (DAP) moieties, capable of multiple hydrogen bonding, was an efficient approach toward forming a-helical-dominant polypeptides. The physically cross-linked networks produced upon self-organization of the DAP units increased the glass transition temperature (T-g) of the polymers and sustained the secondary structures of the polypeptides. Additional thermal responsivity resulted from dynamic noncovalent bonding on the polymer side chains. Molecular recognition through heterocomplementary DAP thymine (T) base pairs was revealed spectroscopically and then used to construct poly(y-propargylL-glutamate)-g-N-(6-acetamidopyridin-2-y1)-11-undecanamide/thyminylpyrene (PPLG-DAP/Py-T) supramolecular complexes. Transmission electron microscopy images revealed that this complex was an efficient dispersant of carbon nanotubes (CNTs). Indeed, it could disperse CNTs in both polar and nonpolar media, the direct result of combining two modes of secondary noncovalent bonding: multiple hydrogen bonding and pi-pi interactions. Furthermore, CNT composites fabricated with biocompatible polymers and high value of T-g should enable the development of bio-inspired carbon nanostructures and lead the way toward their biomedical applications.
Glass transition temperature enhancement of PMMA through copolymerization with PMAAM and PTCM mediated by hydrogen bonding
(2010-02-15)
Lin, Chien-Ting
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Kuo, Shiao-Wei
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Huang, Chih-Feng
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Chang, Feng-Chih
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應用化學系
A series of poly(methyl methacrylate-co-methacrylamide-co-tricyclodecyl methacrylate) (PMMA-co-PMAAM-co-PTCM) copolymers possessing high glass transition temperatures and high transparency are prepared. By incorporating the aliphatic tricyclodecyl methacrylate moiety into the PMMA-co-PMAA main chain results in high glass transition temperature and high transparency of PMMA-based polymeric material. The TCM content affects the fraction of hydrogen bonding in these terpolymers, small content of TCM does not sacrifice the fraction of hydrogen-bonded association in and does not cause T(g) decrease. The extent of free amide group plays the major role in dictating moisture absorption of terpolymers. The incorporation of TCM significantly reduces the moisture absorption of terpolymers due to its hydrophobic and bulky tricyclodecyl group. In addition, the TCM plays the role of inert diluent to convert portion of the strong self-associated hydrogen bonded amide groups into inter-associated hydrogen bonding between carbonyl groups of ester units and MAAM. (C) 2010 Elsevier Ltd. All rights reserved.
Hybridization sensing by electrical enhancement with nanoparticles in nanogap
(2008-11-01)
Chen, Chun-Chi
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Ko, Fu-Hsiang
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Chang, Edward Yi
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Chang, Feng-Chih
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Kuo, Shiao-Wei
In this work, the monolayer of gold nanoparticles within 72 nm gap has been proposed to function as a DNA sensor. The authors suggest that the nanoparticles in the nanogap could act as hopping sites which amplify the conductance of hybridized DNA strands. The conductance amplification between single strand and hybridized DNAs through gold nanoparticles is observed. Various concentrations of capture and target DNA are discussed for optimal hybridization sensing purpose. With the help of 1 nM capture DNAs, this sensor is able to analyze target DNA sequences at very low concentration of 1 fM. Furthermore, by means of adjusting the denature temperature to 60 degrees C, even single mismatch hybridization could be discriminated.
Hydrogen bond mediated supramolecular micellization of diblock copolymer mixture in common solvents
(2009-07-01)
Kuo, Shiao-Wei
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Tung, Pao-Hsaing
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Chang, Feng-Chih
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應用化學系
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Department of Applied Chemistry
We report a new approach toward preparing self-assembled hydrogen-bonded complexes having vesicle and patched spherical structures from two species of block copolymers in nonselective solvents. Two diblock copolymers, poly(styrene-b-vinyl phenol) (PS-b-PvPh) and poly(methyl methacrylate-b-4-vinylpyridine) (PMMA-b-P4VP), were synthesized through anionic polymerization. The assembly of vesicles from the intermolecular complex formed after mixing PS-b-PVPH with PMMA-b-P4VP in THF was driven by strong hydrogen bonding between the complementary binding sites on the PVPH and P4VP blocks. In contrast, well-defined patched spherical micelles formed after blending PS-b-PVPh with PMMA-b-P4VP in DMF: the weaker hydrogen bonds formed between the PVPh and P4VP blocks in DMF, relative to those in THF, resulted in the formation of spherical micelles having compartmentalized coronas consisting of PS and PMMA blocks. (C) 2009 Elsevier Ltd. All rights reserved.
Hydrogen Bond-Mediated Self-Assembly of Polyhedral Oligomeric Silsesquioxane-Based Supramolecules
(2010-08-05)
Shih, Ruey-Sheng
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Lu, Chu-Hua
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Kuo, Shiao-Wei
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Chang, Feng-Chih
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應用化學系
In this study, a functionalized pentaerythritol star polyester compound [tetrakis(nicotinoxymethyl)methane, TNMM] and an octakis[dimethyl(4-hydroxyphenethyl)siloxy]silsesquioxane (OP-POSS) were synthesized and used as tetrahedral and cubic building blocks, respectively, for three-dimensional, hydrogen-bond-mediated, polyhedral oligomeric silsesquioxane- (POSS-) based supramolecular network structures. With noncovalent chain extension of hydrogen bonds between its pyridine and phenol groups, the PUSS-based supramolecular networks exhibited thermally reversible properties. Compared with the glass transition temperature of OP-POSS (ca. 20 degrees C) and the melting temperature of TNMM (ca. 70 degrees C), the hydrogen-bond-mediated miscible blend of 40 wt % TNMM in OP-POSS exhibited a single and higher glass transition temperature (37 degrees C). Because of its strong intermolecular hydrogen bonding, the dewetting pattern of the blend of 40 wt % TNMM in OP-POSS formed ringlike structures rather than the droplets formed by pure OP-POSS. A transparent, brittle, and glassy solid at room temperature, the blend of 40 wt % TNMM in OP-POSS is an explicit and successful example of a PUSS-based hydrogen-bonded supramolecular network.