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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
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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.
Hydrogen Bond-Mediated Self-Assembly of Polyhedral Oligomeric Silsesquioxane-Based Supramolecules
(2010-08-05)
Shih, Ruey-Sheng
;
Lu, Chu-Hua
;
Kuo, Shiao-Wei
;
Chang, Feng-Chih
;
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.
Self-assembly of an A-B diblock copolymer blended with a C homopolymer and a C-D diblock copolymer through hydrogen bonding interaction
(2010-08-19)
Chen, Wan-Chun
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Kuo, Shiao-Wei
;
Chang, Feng-Chih
;
應用化學系
;
Department of Applied Chemistry
In this study, we investigated the miscibility, phase behavior, and self-assembled nanostructures formed from the immiscible crystalline-amorphous diblock copolymer poly(epsilon-caprolactone-b-4-vinyl pyridine) (PCL-b-P4VP, A-B) when blended with the homopolymer poly(vinyl phenol) (PVPh, C) and the diblock copolymer poly(vinyl phenol-b-styrene) (PVPh-b-PS, C-D). Long-range-ordered microphase separation was difficult to achieve in the PCL-b-P4VP/PVPh (A-B/C) blend system because PVPh interacted with both the P4VP and PCL blocks simultaneously through hydrogen bonding interactions. In contrast, we observed sharp, multiple orders of diffraction in the SAXS profiles of the PCL-b-P4VP/PVPh-b-PS (A-B/C D) blend system, indicating that perfect microphase separation occurred because the incorporation of the PS block induced the PVPh block to hydrogen bond preferentially with the P4VP block. This simple A-B/C-D (PCL-b-P4VP/PVPh-b-PS) diblock copolymer mixture exhibited self-assembly behavior (a three-lamella phase) similar to that of a corresponding ABC triblock copolymer. (C) 2010 Elsevier Ltd. All rights reserved.
Preparation and characterization of high-durability zwitterionic crosslinked proton exchange membranes
(2010-10-15)
Ye, Yun-Sheng
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Chen, Wen-Yi
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Huang, Yao-Jheng
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Cheng, Ming-Yao
;
Yen, Ying-Chieh
The present present paper describes the development of a novel proton exchange membrane comprising a poly (styrene sulfonic acid-co-4-vinylpyridine) copolymer that was crosslinked with a haloalkyl crosslinker through the formation of ionic bonding linkages The nucleophilic substitution of these crosslinked membranes as well as a model reaction between pyridine and 1-bromobutane was confirmed by nuclear magnetic resonance (NMR) Tough and flexible membranes of a high mechanical strength were prepared. They demonstrated very elevated thermal, hydrolytic and oxidative stabilities as compared to other sulfonated polymers. The crosslinked membrane composed of zwitterionic molecules with a crosslinking fraction of 90.3, denoted SP-1, exhibited a proton conductivity of ca 7 1 x 10(-2) S cm(-1) at 30 degrees C under 90% relative humidity; a value comparable to that of Nafion 117 Moreover, the crosslinked SP-1 membrane possessed the highest selectivity for methanol fuel cells (3 38 x 10(5) S cm(-3) s), approximately five times that of Nafion 117. thus implying its potential for practical use in high-energy-density devices (C) 2010 Elsevier B.V All rights reserved.
Thermal properties and liquid crystallinity of side-chain azobenzene copolymer containing pendant polyhedral oligomeric silsequioxanes
(2010-11-01)
Wang, Xiao-Tao
;
Yang, Ying-Kui
;
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.
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
;
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.
Design of Artificial Hollow Moth-Eye Structures Using Anodic Nanocones for High-Performance Optics
(2010-12-28)
Wu, Chia-Tien
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Lin, Chun-Hung
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Cheng, Chieh
;
Wu, Chung-Shu
;
Ting, Huai-Chen
We demonstrated an innovative approach for the fabrication of self-organized, hollow-to-solid nanocone arrays, using a decoupling two-step anodization of an Al/Ta interlayer on a substrate. The porosity of the hollow nanostructures was tunable by the deposited thickness of Ta film. We also employed subwavelength nanocone arrays as Moth-eye structures for high-performance antireflection coatings. These oxide nanostructures greatly suppressed reflectance over a large range of wavelengths and angles of incidence and displayed a good mechanical stability. When a corresponding porosity was designed, these nanostructures could be applied to various substrates for an effective antireflection coating. In addition, we were able to customize antireflection coatings for various types of substrates or materials of interest based on the suitable coating of initial Ta thickness.

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