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High-efficiency self-healing materials based on supramolecular polymer networks
(2015-01-01)
Cheng, Chih-Chia
;
Chang, Feng-Chih
;
Chen, Jem-Kun
;
Wang, Tzu-Yin
;
Lee, Duu-Jong
Supramolecular polymers, a combination of secondary interactions and a polymer material, can be used to control supramolecular self-assembly in a polymeric matrix; these materials exhibit unique stimuli-responsiveness and self-healing properties making them highly attractive for various applications. Herein, we developed a novel supramolecular poly-urea containing a urea-cytosine (UrCy) quadruple hydrogen bonding moiety that undergoes a dynamic healing mechanism, "supramolecular polymer networks (SPN)", and rapidly repairs after damage under mild conditions. Interestingly, this newly-developed material can also self-heal at room temperature without external intervention, as evidenced by repeated restoration of mechanical properties. Given its simplicity, efficiency and reliability, this material offers a unique paradigm for developing SPN-based self-healing materials.
Photo-Crosslinking of Pendent Uracil Units Provides Supramolecular Hole Injection/Transport Conducting Polymers for Highly Efficient Light-Emitting Diodes
(2015-05-01)
Shih, Hsi-Kang
;
Chen, Yi-Han
;
Chu, Yu-Lin
;
Cheng, Chih-Chia
;
Chang, Feng-Chih
A new process for modifying a polymeric material for use as a hole injection transport layer in organic light-emitting diodes has been studied, which is through 2 + 2 photodimerization of a DNA-mimetic -conjugated poly(triphenylamine-carbazole) presenting pendent uracil groups (PTC-U) under 1 h of UV irradiation. Multilayer florescence OLED (Organic light-emitting diodes) device with the PTC-U-1hr as a hole injection/transport layer (ITO (Indium tin oxide)/HITL (hole-injection/transport layer) (15 nm)/N,N'-di(1-naphthyl)-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (NPB) (15 nm)/Tris-(8-hydroxyquinoline)aluminum (Alq(3)) (60 nm)/LiF (1 nm)/Al (100 nm)) is fabricated, a remarkable improvement in performance (Q(max) (external quantum efficiency) = 2.65%, B-max (maximum brightness) = 56,704 cd/m(2), and LE (luminance efficiency)(max) = 8.9 cd/A) relative to the control PTC-U (Q(max) = 2.40%, B-max = 40,490 cd/m(2), and LEmax = 8.0 cd/A). Multilayer phosphorescence OLED device with the PTC-U-1hr as a hole injection/transport layer (ITO/HITL (15 nm)/Ir(ppy)(3):PVK (40 nm)/BCP (10nm)/Alq(3) (40 nm)/LiF (1 nm)/Al (100 nm)) is fabricated by successive spin-coating processes, a remarkable improvement in performance (Q(max) = 9.68%, B-max = 41,466 cd/m(2), and LEmax = 36.6 cd/A) relative to the control PTC-U (Q(max) = 8.35%, B-max = 34,978 cd/m(2), and LEmax = 30.8 cd/A) and the commercial product (poly(3,4-ethylenedioxythiophene):polystyrenesulfonate) PEDOT:PSS (Q(max) = 4.29%, B-max = 15,678 cd/m(2), and LEmax = 16.2 cd/A) has been achieved.
Bio-complementary supramolecular polymers with effective self-healing functionality
(2015-01-01)
Cheng, Chih-Chia
;
Chang, Feng-Chih
;
Dai, Shenghong A.
;
Lin, Yu-Li
;
Lee, Duu-Jong
Complementary nucleobase-functionalized polymers, a combination of base-pair interactions and a blend of two different polymers, can be used for efficient construction of supramolecular polymer networks; these materials exhibit tunable mechanical properties, rapid thermo-responsiveness and self-healing behavior making them highly attractive for a wide range of potential applications. Herein, a multi-uracil functionalized polyhedral oligomeric silsesquioxane (POSS-U) and adenine end-capped three-arm polycaprolactone oligomer (PCL-A) have been successfully developed and show high complementary ability in both solution and the solid state owing to reversible uracil-adenine (U-A)-induced physical cross-linking. The POSS-U/PCL-A blend system demonstrates that physically crosslinked films can be readily tailored to provide the desired mechanical properties and rapidly reprocessed after damage under mild temperature conditions. Importantly, these films can also spontaneously self-heal at room temperature as an autonomously repairing material, without the need for external intervention. Thus, this new system provides a potential route toward the design and fabrication of next-generation self-healing polymers.
Large-scale production of ureido-cytosine based supramolecular polymers with well-controlled hierarchical nanostructures
(2015-01-01)
Cheng, Chih-Chia
;
Chang, Feng-Chih
;
Wang, Jui-Hsu
;
Chu, Yu-Lin
;
Wang, Yeh-Sheng
A novel supramolecular polymer containing urea-cytosine (UrCy) quadruple hydrogen-bonding moieties that possesses a high association constant (K-a > 10(6) M-1) was synthesized at high yield (96%) at kilogram-scale. The synthesized telechelic macromer dissolved in solution can undergo a substantial change in solution viscoelasticity and can self-assemble due to the noncovalent nature of supramolecular polymerization. As the concentration of UrCy in solution was increased, the spherical assemblies gradually transformed to an ordered lamellar phase with an extremely high degree of polymerization. In addition, the dynamic behavior of UrCy units induced a sudden phase transition in the bulk state, revealing an interesting order-disorder transition from a crystalline solid to liquid state. This newly-discovered material has excellent polymer-like features that are distinct to existing systems. A simple path for forming supramolecular polymers is recommended for the design, large-scale production and manipulation of self-assembled materials with distinctive properties.
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
;
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.
Thermal properties and liquid crystallinity of side-chain azobenzene copolymer containing pendant polyhedral oligomeric silsequioxanes
(2010-11-01)
Wang, Xiao-Tao
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Yang, Ying-Kui
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Yang, Zhi-Fang
;
Zhou, Xing-Ping
;
Liao, Yong-Gui
Vinylated polyhedral oligomeric silsesquioxane (POSS-M) was prepared by the reaction of POSS containing amine groups with acrylic acid. Azobenzene liquid crystalline copolymer (LCP-POSS) was then synthesized with 6.0 mol% POSS-M and 94.0 mol% acrylate monomer containing azobenzene liquid crystalline moiety (Azo-M) by free-radical copolymerization. Homopolymer of Azo-M (LCP) was also synthesized under the same conditions. Their thermal properties and liquid crystallinity were characterized by Thermal gravimetric analysis (TG), differential scanning calorimetry (DSC), Wide-angle X-ray diffraction experiments (XRD) and polarized optical micrographs (POM). The results showed that LCP-POSS has higher thermal stability and glass transition temperature than pure LCP due to the incorporation of the rigid cage-like POSS. Especially, LCP-POSS exhibits enantiotropic smectic and nematic liquid crystalline behaviors, its smectic-nematic transition temperature (T (SN)) and nematic-isotropic transition temperature (T (NI)) are higher than those of pure LCP, which may promote and extend its applications on stimuli-responsive materials and devices.
Removal of Hg2+ from Aqueous Solution Using a Novel Composite Carbon Adsorbent
(2009-05-15)
Chang, Yu-Hsin
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Hsieh, Kuo-Huang
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Chang, Feng-Chih
;
應用化學系
;
Department of Applied Chemistry
A novel composite carbon adsorbent (GCA) has been prepared by immobilizing activated carbon and genipin-crosslinked chitosan into calcium alginate gel beads via entrapment and applied to the removal of mercury (Hg2+) ions from aqueous solution (e.g., drinking water). Two bead sizes and two mixing ratios of components were obtained and characterized. Batch experiments were performed to study the Uptake equilibrium and kinetics, of Hg2+ ions by the GCA. The Hg2+ adsorption capacity of GCA was found to be dependent of pH and independent of size of the adsorbent. The Hg2+ adsorption rate of GCA increases with decreasing its bead size. However, both adsorption capacity and rate of GCA for Hg2+ increase with increasing its chitosan content. Otherwise, it was shown that the GCA has higher Hg2+ adsorption capacity and rate than activated carbon, which might he caused by the incorporation of chitosan into the GCA. The maximum Hg2+ adsorption capacity of GCA was found to be 576 mg/g, which is over seven times higher than that of activated carbon. Our results reveal the uniform distribution of activated carbon and chitosan within the alginate gel bead and that Hg2+ ions can diffuse inside the bead. It also demonstrated the feasibility of using this GCA for Hg2+ removal at low pH values. The Hg2+ absorbed beads of the GCA can be effectivelY regenerated and reused using H2SO4. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 112: 2445-2454, 2009
Improved reliability from a plasma-assisted metal-insulator-metal capacitor comprising a high-k HfO2 film on a flexible polyimide substrate
(2010-01-01)
Meen, Jagan Singh
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Chu, Min-Ching
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Kuo, Shiao-Wei
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Chang, Feng-Chih
;
Ko, Fu-Hsiang
We have used a sol-gel spin-coating process to fabricate a new metal-insulator-metal (MIM) capacitor comprising a 10 nm-thick high-k thin dielectric HfO2 film on a flexible polyimide (PI) substrate. The surface morphology of this HfO2 film was investigated using atomic force microscopy and scanning electron microscopy, which confirmed that continuous and crack-free film growth had occurred on the film surface. After oxygen (O-2) plasma pretreatment and subsequent annealing at 250 degrees C, the film on the PI substrate exhibited a low leakage current density of 3.64 x 10(-9) A cm(-2) at 5 V and a maximum capacitance density of 10.35 fF mu m(-2) at 1 MHz. The as-deposited sol-gel film was completely oxidized when employing O2 plasma at a relatively low temperature (ca. 250 degrees C), thereby enhancing the electrical performance. We employed X-ray photoelectron spectroscopy (XPS) at both high and low resolution to examine the chemical composition of the film subjected to various treatment conditions. The shift of the XPS peaks towards higher binding energy, revealed that O-2 plasma treatment was the most effective process for the complete oxidation of hafnium atoms at low temperature. A study of the insulator properties indicated the excellent bendability of our MIM capacitor; the flexible PI substrate could be bent up to 10(5) times and folded to near 360 degrees without any deterioration in its electrical performance.
Highly reliable Si3N4-HfO2 stacked heterostructure to fully flexible poly-(3-hexylthiophene) thin-film transistor
(2011-08-01)
Meena, Jagan Singh
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Chu, Min-Ching
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Wu, Chung-Shu
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Chang, Feng-Chih
;
Ko, Fu-Hsiang
A new and fully flexible Si3N4-HfO2 stacked poly-(3-hexylthiophene) p-type thin film transistor (P3HT-TFT) was successfully fabricated on thin semi-transparent polyimide (PI) substrate. The success of the TFT manufacturing adopts: (a) very simple and cost-effective sol-gel spin-coating technique to obtain 10-nm high-k HfO2 as dielectric layer over fully flexible PI substrate; (b) 50-nm silicon nitride (Si3N4) as the most efficient passivation layer on top of HfO2 film; (c) bendable 30-nm P3HT channel film by spin-coating method. Current-electric field characteristics of HfO2 layer in metal-insulator-metal (MIM) and TFT configurations, with or without Si3N4 passivation layer, were carefully evaluated. The origin of unsatisfactory leakage current in MIM and TFT structures could be effectively suppressed by means of Si3N4 film as the efficient passivation layer. The bottom-gate TFT demonstrated the on-to-off ratio 2 x 10(4) for drain current, -1.9 V threshold voltage and good saturation mobility (0.041 cm(2) V (1) s (1)). The proposed devices were examined in convex and concave types of various radii of curvature (R-C) in order to explore the manufacturing feasibility and electrical reliability of the fully flexible TFT for practical applications. In addition, various folding times and environmental stability on aforementioned devices with respective to electrical performances were also evaluated. (C) 2011 Elsevier B.V. All rights reserved.
Plasma-enhanced flexible metal-insulator-metal capacitor using high-k ZrO2 film as gate dielectric with improved reliability
(2010-08-01)
Chu, Min-Ching
;
Meena, Jagan Singh
;
Cheng, Chih-Chia
;
You, Hsin-Chiang
;
Chang, Feng-Chih
We demonstrate a new flexible metal-insulator-metal capacitor using 9.5-nm-thick ZrO2 film on a plastic polyimide substrate based on a simple and low-cost sal-gel precursor spin-coating process. The surface morphology of the ZrO2 film was investigated using scan electron microscope and atomic force microscope. The as-deposited ZrO2 film under suitable treatment of oxygen (O-2) plasma and then subsequent annealing at 250 degrees C exhibits superior low leakage current density of 9.0 x 10(-9) A/cm(2) at applied voltage of 5 V and maximum capacitance density of 13.3 fF/mu m(2) at 1 MHz. The as-deposited sol-gel film was completely oxidized when we employed O-2 plasma at relatively low temperature and power (30 W), hence enhancing the electrical performance of the capacitor. The shift (Zr 3d from 184.1 eV to 184.64 eV) in X-ray photoelectron spectroscopy of the binding energy of the electrons towards higher binding energy; clearly indicates that the O-2 plasma reaction was most effective process for the complete oxidation of the sol-gel precursor at relatively low processing temperature. (C) 2010 Elsevier Ltd. All rights reserved.

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