Browsing by Author "Huang, Cheng-Wei"

Now showing 1 - 7 of 7

A solvent-resistant azide-based hole injection/transporting conjugated polymer for fluorescent and phosphorescent light-emitting diodes
(2015-01-01)
Huang, Cheng-Wei
;
Chang, Feng-Chih
;
Chu, Yu-Lin
;
Lai, Cheng-Chang
;
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.
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
;
Mohamed, Mohamed Gamal
;
Zhu, Chao-Yuan
;
Kuo, Shiao-Wei
;
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.
Nucleobase-grafted polycaprolactones as reversible networks in a novel biocompatible material
(2013)
Lin, I. -Hong
;
Cheng, Chih-Chia
;
Huang, Cheng-Wei
;
Liang, Mei-Chih
;
Chen, Jem-Kun
A series of nucleobase-grafted polycaprolactones have been prepared which exhibits a high complementary ability in solution and solid states owing to the formation of uracil-adenine pairs by induced hierarchical self-assembly. In addition, they can self-organize into spherical structure and result in excellent biomaterial properties.
Stimuli-responsive supramolecular materials: photo-tunable properties and molecular recognition behavior
(2016)
Huang, Cheng-Wei
;
Wu, Pei-Wei
;
Su, Wei-Hung
;
Zhu, Chao-Yuan
;
Kuo, Shiao-Wei
A new homopolymer of polystyrene (PS) presenting pendant diaminopyridine (DAP) moieties has been prepared using controlled free radical polymerization and a CuAAC "click" reaction. Through directional complementary multiple hydrogen bonding, this PVB-DAP polymer underwent complexation with a thymine-functionalized azobenzene (Azo-T). The resulting supramolecular complex exhibited amorphous and chromophoric behavior without microphase separation. This strategy allowed the fabrication of homogeneous stimuli-responsive thin films with photocontrollable behavior through photoinduced trans-cis isomerization. The PVB-DAP/Azo-T supramolecular complex facilitated the dispersion of an azo-dye through noncovalent interactions; the resulting complex was used to fabricate a surface relief grating displaying an interference pattern. The "recordability" and "rewritability" of these supramolecular complexes suggest that they are promising materials for optical applications and therefore advance the pathway for supramolecular development.
Stimuli-responsive supramolecular materials: photo-tunable properties and molecular recognition behavior
(2016-01-01)
Huang, Cheng-Wei
;
Wu, Pei-Wei
;
Su, Wei-Hung
;
Zhu, Chao-Yuan
;
Kuo, Shiao-Wei
A new homopolymer of polystyrene (PS) presenting pendant diaminopyridine (DAP) moieties has been prepared using controlled free radical polymerization and a CuAAC "click" reaction. Through directional complementary multiple hydrogen bonding, this PVB-DAP polymer underwent complexation with a thymine-functionalized azobenzene (Azo-T). The resulting supramolecular complex exhibited amorphous and chromophoric behavior without microphase separation. This strategy allowed the fabrication of homogeneous stimuli-responsive thin films with photocontrollable behavior through photoinduced trans-cis isomerization. The PVB-DAP/Azo-T supramolecular complex facilitated the dispersion of an azo-dye through noncovalent interactions; the resulting complex was used to fabricate a surface relief grating displaying an interference pattern. The "recordability" and "rewritability" of these supramolecular complexes suggest that they are promising materials for optical applications and therefore advance the pathway for supramolecular development.
Superhydrophobic Si nanowires for enhanced condensation heat transfer
(2017-08-01)
Lu, Ming-Chang
;
Lin, Chien-Chang
;
Lo, Ching-Wen
;
Huang, Cheng-Wei
;
Wang, Chi-Chuan
Condensation is an essential process in various industrial systems. Enhancing condensation by employing superhydrophobic (SHB) surfaces had drawn significant attention in recent years because of the emerging technology for surface engineering. However, the efficacy of SHB surfaces in condensation is controversy in the literature. The observed deteriorated heat transfer on SHB in condensation is presumably a result of highly pinned Wenzel droplets or flooding formed on the SHB surfaces. Si nanowire (SiNW) array-coated surface which can simultaneously provide a large number of nucleation sites and prevent condensate from penetrating into the nano-structure is a promising candidate for enhancing condensation. In this work, heat transfer on the SHB SiNW surface was investigated. At low subcooling, jumping of liquid droplets accompanied with a high droplet departure frequency resulted in a large heat transfer coefficient (HTC) of 88 16 kW/m(2) K on the SHB surface. This value is one of the highest reported condensation HTCs in the literature. It was 155% and 87% higher than those on the plain hydrophilic and hydrophobic surfaces, respectively. Heat transfer decreased with the rise of subcooling due to an increased condensate surface coverage ratio. However, condensate can still be rapidly shed away from the SHB SiNW surface at high subcooling, which render the comparatively larger HTC of 18.6 2 kW/m(2) K on the SHB SiNW surface as opposed to plain hydrophobic and hydrophilic surfaces. It was evidenced that SHB surface could have a superior heat and mass transfer performance than hydrophobic surface provided that the liquid droplets on the SHB could be shed away efficiently. (C) 2017 Elsevier Ltd. All rights reserved.
Synthesis and self-assembly of water-soluble polythiophene-graft-poly(ethylene oxide) copolymers
(2014)
Mohamed, Mohamed Gamal
;
Cheng, Chih-Chia
;
Lin, Yung-Chih
;
Huang, Cheng-Wei
;
Lu, Fang-Hsien
In this study, we synthesized amphiphilic poly(3-hexylthiophene)-graft-poly(ethylene oxide) (P3HT-g-PEO) rod-coil conjugated random copolymers through oxidative polymerization with FeCl3 and facile click chemistry and characterized them using H-1 nuclear magnetic resonance spectroscopy, size exclusion chromatography, differential scanning calorimetry (DSC), X-ray photoelectron spectroscopy, UV-Vis spectroscopy, and fluorescence spectroscopy. We then used atomic force microscopy, transmission electron microscopy, and dynamic light scattering to investigate the self-assembled structures formed from these amphiphilic random copolymers in solution and in the bulk state. In the bulk state, DSC analyses revealed that after PEO had been grafted onto P3HT, the crystallization temperature of PEO decreased from +20 to -26 degrees C as a result of hard confinement of microphase separation in the copolymer system. In addition, we found that the amphiphilic conjugated random copolymers could form micelle structures in the DMF-water system.