Browsing by Author "Liang, Gao-Wei"

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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
;
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).