Browsing by Author "Ye, Yun-Sheng"

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A new graphene-modified protic ionic liquid-based composite membrane for solid polymer electrolytes
(2011)
Ye, Yun-Sheng
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Tseng, Chi-Yung
;
Shen, Wei-Chung
;
Wang, Jing-Shiuan
;
Chen, Kuan-Jung
The production of a solid polymer electrolyte with high ionic conductivity and mechanical properties is the main fabrication challenge in application of polymer electrolyte membranes. This paper describes a novel polymer electrolyte membrane using protic ionic liquids (PILs) with ionic liquid polymer modified graphene (G) sheets [denoted PIL(NTFSI)-G] that exhibit dramatic enhancements in ionic conductivity (257.4%) and mechanical properties (345% improvement in tensile strength and a near 25-fold increase in modulus were achieved at 150 degrees C) with a minimal loading of PIL(NTFSI)-G (0.5 wt %). The addition of graphene, by sparing the high-cost PIL addition, gives a 20% cost-saving. The homogeneous distribution of graphene sheets as a 3D network through the polymer matrix in the composite membrane provides a high degree of continuous and interconnected transfer channels to facilitate ion transfer and enhance nanofiller-matrix adhesion to reinforce mechanical properties. This newly developed material provides a potential route toward the design and fabrication of polymer electrolytes.
A new organic/inorganic electroluminescent material with a silsesquioxane core
(2009-04-01)
Cheng, Chih-Chia
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Chien, Chen-Han
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Yen, Ying-Chieh
;
Ye, Yun-Sheng
;
Ko, Fu-Hsiang
This paper describes a new polyhedral oligomeric silsesquioxane (POSS)-based blue-light electroluminescent nanoparticle, octakis[N-(9-ethyl-9-H-carbazol-3-yl)undecanamide-11-dimethylsiloxy]silsesquioxane (POSS-C11-Cz), which contains eight carbazole chromophore arms, synthesized through the hydrosilation reaction of octakis(dimethylsiloxy)silsesquioxane with the terminal olefin Cz-C11ene. POSS-C11-Cz exhibits good thermal and electrochemical stabilities and good film-forming properties. The optical and photoluminescence spectra of POSS-C11-Cz in solution and in the solid state indicate a reduction in the degrees of aggregation and excimer formation because inter-chain interactions were prohibited by the bulky POSS core. Moreover, photoluminescence spectra of a POSS-C11-Cz (3 wt.%,)/polyfluorene (97 blend revealed that the color was stable after heating the sample at 200 degrees C for 5 h; in contrast, the pure polyfluorene exhibited a significant green emission at 530 nm. A triple-layer device based on this blend exhibited higher maximum brightness and luminance efficiencies relative to those of the pure polyfluorene. Thus, the organic/inorganic POSS-C11-Cz/polyfluorene blend has potential for use in polymeric light-emitting diodes because of its improved thermal and optoelectronic characteristics. Published by Elsevier Ltd on behalf of Acta Materialia Inc.
A new supramolecular sulfonated polyimide for use in proton exchange membranes for fuel cells
(2010)
Ye, Yun-Sheng
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Huang, Yao-Jheng
;
Cheng, Chih-Chia
;
Chang, Feng-Chih
;
應用化學系
Uracil-terminated telechelic sulfonated polyimides (SPI-U) were transformed into noncovalent network membranes through biocomplementary hydrogen bonding recognition in the presence of an adenine-based crosslinking agent. SPI-U membrane exhibited dramatically improved methanol permeability, oxidative stability, proton conductivity, and selectivity relative to those of the standard SPI.
A simple approach toward low-dielectric polyimide nanocomposites: Blending the polyimide precursor with a fluorinated polyhedral oligomeric silsesquioxane
(2008-09-15)
Ye, Yun-Sheng
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Yen, Ying-Chieh
;
Chen, Wen-Yi
;
Cheng, Chih-Chia
;
Chang, Feng-Chih
This article describes a new and simple method for preparing polyimide nanocomposites that have very low dielectric constants and good thermal properties: simply through blending the polyimide precursor with a fluorinated polyhedral oligomeric silsesquioxane derivative, octakis(dimethylsiloxyhexafluoropropyl) silsesquioxane (OF). The low polarizability of OF is compatible with polyimide matrices, such that it can improve the dispersion and free volume of the resulting composites. Together, the higher free volume and lower polarizability of OF are responsible for the lower dielectric constants of the PI-OF nanocomposites. This simple method for enhancing the properties of polyimides might have potential applicability in the electronics industry. (C) 2008 Wiley Periodicals, Inc.
Biocomplementary Interaction Behavior in DNA-Like and RNA-Like Polymers
(2009-12-01)
Cheng, Chih-Chia
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Yen, Ying-Chieh
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Ye, Yun-Sheng
;
Chang, Feng-Chih
;
應用化學系
A series of nucleobased polymers and copolymers were synthesized through atom transfer radical polymerization (ATRP). Biocomplementary DNA-and RNA-like supramolecular complexes are formed in dilute DMSO solution through nucleobase recognition. (1)H NMR titration studies of these complexes in CDCl(3) indicated that thymine-adenine (T-A) and uracil-adenine (U-A) complexes form rapidly on the NMR time scale with high association constants (up to 534 and 671 M(-1), respectively) and result in significant T(g) increase. WAXD and differential scanning calorimetry analyzes in the bulk state indicate the presence of highly physical crosslinked structures and provide further details into the nature of the self-assembly of these systems. Furthermore, this study is of discussion on the difference in the hydrogen bond strength between T-A and U-A base pairs within polymer systems, indicating that the strength of hydrogen bonds in RNA U-A pairs is stronger than that in DNA T-A base pairs. (C) 2009 Wiley Periodicals, Inc. J Polym. Sci Part A: Polym Chem 47:6388-6395, 2009
Bioinspired Photo-Cross-Linked Nanofibers from Uracil-Functionalized Polymers
(2012-01-01)
Wang, Yeh-Sheng
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Cheng, Chih-Chia
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Ye, Yun-Sheng
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Yen, Ying-Chieh
;
Chang, Feng-Chih
In this study, we used electrospinning to fabricate nucleobase-functionalized and photo-cross-linkable poly[1-(4-vinylbenzyl uracil)] (PVBU) nanofibers. PVBU of high-molecular-weight (M-n > 250 550 g/mol) possessed a high thermal stability and sufficient chain entanglement to produce uniform fibers without forming beads. These uracil-functionalized nanofibers were further photo-cross-linked through exposure to UV light at a wavelength of 254 nm. After immersing in N,N-dimethylacetamide, the pristine PVBU fibers dissolved, while the cross-linked PVBU fibers maintained their shape; thus, the cross-linked PVBU nanofibers exhibited good dimensional stability and improved solvent resistance.
Effect of LiClO4 on the thermal and morphological properties of organic/inorganic polymer hybrids
(2008-08-11)
Yen, Ying-Chieh
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Ye, Yun-Sheng
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Cheng, Chih-Chia
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Chen, Hsiu-Mei
;
Sheu, Hwo-Shuenn
This paper describes the thermal properties, morphologies, and interactions within the binary and ternary blends of poly(methyl methacrylate) (PMMA), octa(phenol)octasilsesquioxane (OP-POSS), and LiClO4. In the binary PMMA/OP-POSS blends, the OP-POSS molecules tend to aggregate and result in a decrease (19 degrees C) in the glass transition temperature. In the ternary PMMA/LiClO4/OP-POSS blends, however, the OP-POSS molecules form small sphere-like domains (20 nm) leading to the composite's glass transition temperature increasing by up to 30 degrees C. Based on these FF-IR spectra, the addition of LiClO4 influenced the probability of hydrogen bonds formed between PMMA and OP-POSS and these SEM micrographs, DSC, and XRD data indicated that the addition of LiClO4 is a convenient and simple approach toward dispersing the OP-POSS nanoparticles within PMMA, where the presence of LiClO4 changes the physical effect of OP-POSS from that of a diluent role to a cross-linker role. (c) 2008 Elsevier Ltd. All rights reserved.
Effect of morphology of mesoporous silica on characterization of protic ionic liquid-based composite membranes
(2011-07-01)
Ye, Yun-Sheng
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Liang, Gao-Wei
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Chen, Bo-Han
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Shen, Wei-Chung
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Tseng, Chi-Yung
Effects caused by the morphology of mesoporous silica on the characterization of protic ionic liquid-based composite membranes for anhydrous proton exchange membrane applications are investigated. Two types of SBA15 materials with platelet and fiberlike morphologies are synthesized and incorporated into a mixture of polymerizable monomers together with an ionic liquid (IL)[1-butyl-3-methylimidazolium bis(trifluoromethane sulfone)imide (BMIm-TFSI)] to form new conducting membranes using an in situ photo crosslinking process. Incorporation of a defined amount of fiber-shaped SBA 15 and platelet 15 significantly increases the ionic conductivity to between two and three times that of a plain poly(methyl methacrylate) (PMMA)/IL membrane (2.3 mS cm(-1)) at 160 degrees C. The protic ionic liquid (PIL) retention ability of the membranes is increased by the capillary forces introduced by the mesoporous silica materials, while ionic conductivity loss after leaching test is retarded. The highest ionic conductivity (5.3 mS cm(-1)) is obtained by incorporating 5 wt% of P-SBA 15 in the membrane to about six times that of plain PMMA/IL membrane (0.9 mS cm(-1)) at 160 degrees C after leaching test. (C) 2011 Elsevier B.V. All rights reserved.
Polytriazole/clay nanocomposites synthesized using in situ polymerization and click chemistry
(2010-01-21)
Ye, Yun-Sheng
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Yen, Ying-Chieh
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Cheng, Chih-Chia
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Syu, Yu-Jyuan
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Huang, Yao-Jeng
This manuscript describes the preparation of polytriazole/clay nanocomposites through in situ polymerization of PTA, using click chemistry, in the presence of a propargyl-modified clay. The clay layers became exfoliated and dispersed well in the PTA matrix, thereby improving the thermal and mechanical properties of the clay. This approach can be extended to combine propargyl-modified clays with other azide- and alkyne-containing polymers. (C) 2009 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
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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.
Sulfonated poly(ether ether ketone) membranes crosslinked with sulfonic acid containing benzoxazine monomer as proton exchange membranes
(2009-07-03)
Ye, Yun-Sheng
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Yen, Ying-Chieh
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Cheng, Chih-Chia
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Chen, Wen Yi
;
Tsai, Li-Tuan
The incorporation of benzoxazine (Ba) or sulfonic acid containing benzoxazine (SBa) as a crosslinking agent in SPEEK proton exchange membrane (PEM) can substantially improve the SPEEK membrane performance. The SPEEK-SBa membranes give higher effective selectivity than corresponding SPEEK-Ba membranes under close crosslinker loading and thus are more suitable to be used in direct methanol fuel cells. The best achieved SPEEK-SBa composition (SBa40) gives reasonable proton conductivity (0.91 x 10(-2) S cm(-1)) but significantly lower methanol permeability (6.5 x 10(-8) 52 cm(-1)). The achieved effective selectivity (Phi = SPEEK-SBa40: 14.0 x 10(4) S s cm(-3)) is substantially higher than the plain SPEEK (Phi = 7.24 x 10(4) S s cm(-3)) which has great potential for practical applications in DMFCs. (C) 2009 Elsevier Ltd. All rights reserved.
Synthesis and characterization of sulfonated polytriazole-clay proton exchange membrane by in situ polymerization and click reaction for direct methanol fuel cells
(2012-06-15)
Huang, Yao-Jheng
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Ye, Yun-Sheng
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Syu, Yu-Jyuan
;
Hwang, Bing-Joe
;
Chang, Feng-Chih
Sulfonated polytriazole-clay (SFTA-clay) nanocomposites are successfully prepared by in situ polymerization of SPTA using click chemistry in the presence of propargyl-functionality modified clay. The clay layers are exfoliated and well dispersed within the SPTA matrix resulting in improvements in thermal stability, mechanical strength, methanol permeability, water retention, ion channel size, and ionic cluster distribution. The SPTA-clay nanocomposite membranes with small amounts of clay in the SPTA matrices possess higher selectivity's; defined as the ratio of proton conductivity to methanol permeability, and thus have potential as proton exchange membranes (PEMs) in direct methanol fuel cells (DMFCs). (C) 2012 Elsevier B.V. All rights reserved.
The effect of sulfonic acid groups within a polyhedral oligomeric silsesquioxane containing cross-linked proton exchange membrane
(2010-01-06)
Yen, Ying-Chieh
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Ye, Yun-Sheng
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Cheng, Chih-Chia
;
Lu, Chu-Hua
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Tsai, Li-Duan
In this study, polyhedral oligomeric silsesquioxane (POSS) moieties were incorporated into sulfonated poly(ether ether ketone) (SPEEK) to form a new cross-linked proton exchange membrane (PEM). The distribution of the POSS containing cross-linkers with or without sulfonic acid groups dictates the water behavior and connectivity of hydrophilic domains of the PEM. A PEM formed by incorporating 17.5 wt% of the cross-linker (containing POSS macromer and sulfonic acid groups) into SPEEK exhibits high proton conductivity (0.0153 S/cm), low methanol permeability (1.34 x 10(-7) cm(2)/s), and high selectivity (1.14 x 10(5) Ss/cm(3)). (C) 2009 Elsevier Ltd. All rights reserved.
Versatile Grafting Approaches to Functionalizing Individually Dispersed Graphene Nanosheets Using RAFT Polymerization and Click Chemistry
(1970-01-01)
Ye, Yun-Sheng
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Chen, Yun-Nian
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Wang, Jing-Shiuan
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Rick, John
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Huang, Yao-Jheng
"Developing powerful and reliable strategies to covalently functionalize graphene for efficient grafting and achieving precise interface control remains challenging due to the strong interlayer cohesive energy and the surface inertia of graphene. Here, we present versatile and efficient grafting strategies to functionalize graphene nanosheets. An alkyne-bearing graphene core was used to prepare polymer-functionalized graphene using 'grafting to' and 'grafting from' strategies in combination with reversible chain transfer and click chemistry. The use of the 'grafting to' approach allows full control over limited length grafted 0 polymer chains, while permitting a high grafting density to a single graphene face, resulting in good solubility and processability. The 'grafting from' approach offers complementary advantages, such as the grafting of high molecular weight polymer chains and a better coverage ratio on the graphene surface; however, the extra steps introduced, the presence of initiating groups, and difficulty in controlling the grafted polymer lead to decreased processability. Various types of polymer chains have been successful covalently tethered to graphene nanosheets using these two approaches, producing various molecular brushes with multifunctional arms resulting in water-soluble, oil-soluble, acidic, basic, polar, apolar, and variously functionalized polymers. This work describes versatile methodologies, using the 'grafting to' and 'grafting from' approaches, for the preparation of individually dispersed graphene nanosheets having the desirable properties described."
Versatile grafting approaches to star-shaped POSS-containing hybrid polymers using RAFT polymerization and click chemistry
(2011)
Ye, Yun-Sheng
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Shen, Wei-Chung
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Tseng, Chi-Yung
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Rick, John
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Huang, Yao-Jheng
An alkyne-bearing polyhedral oligomeric silsesquioxane (POSS) core was used to prepare POSS-containing polymer hybrids using 'grafting to' or 'grafting from' strategies in combination with reversible chain transfer and click chemistry.