Browsing by Author "Rick, John"

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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.
Effect of morphology of mesoporous silica on characterization of protic ionic liquid-based composite membranes
(2011-07-01)
Ye, Yun-Sheng
;
Liang, Gao-Wei
;
Chen, Bo-Han
;
Shen, Wei-Chung
;
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.
New proton conducting membranes with high retention of protic ionic liquids
(2011)
Ye, Yun Sheng
;
Cheng, Ming Yao
;
Tseng, Ji Yong
;
Liang, Gao-Wei
;
Rick, John
New proton conducting membranes, exhibiting a high proton conductivity (10(-2) S cm(-1), without humidification at 160 degrees C), based on the ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate (BMIm-BF(4)) were investigated. The incorporation of a similar initial IL loading was found to reduce the proton conductivity loss of a sulfonated polydiacetylene based membrane, i.e. SPDA70-IL70 by 19.2% and IL-based Nafion by 64.6%; additionally, the SPDA70-IL70 was able to maintain a proton conductivity of more than 10(-3) S cm(-1) after centrifugation. The introduction of both a cross-linked structure and a high degree of sulfonation into the polymer matrix, resulted in significant improvements to the membranes' thermal properties, the dispersion of ionic domains, and the retention of IL-together with a reduction of proton conductivity loss. The membranes, which have a high degree of sulfonation with thermally cross-linkable diacetylene in the polymer's main chain, avoid the drawback of poor miscibility commonly associated with sulfonated polymers and cross-linking agents. When the composite membrane was used in a H(2)/O(2) fuel cell without humidification at 100 degrees C, a power density > 250 mA cm(-2) was achieved together with a maximum current denisty of 122 mW cm(-2).
Versatile Grafting Approaches to Functionalizing Individually Dispersed Graphene Nanosheets Using RAFT Polymerization and Click Chemistry
(1970-01-01)
Ye, Yun-Sheng
;
Chen, Yun-Nian
;
Wang, Jing-Shiuan
;
Rick, John
;
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
;
Shen, Wei-Chung
;
Tseng, Chi-Yung
;
Rick, John
;
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.