In situ implantation of PolyPOSS blocks in Nafion (R) matrix to promote its performance in direct methanol fuel cell
ABSTRACT Fabrication of recast Nafion®-117 membrane using the dipolar aprotonic solvent will normally lead to a random matrix. On the contrary, when a designed amount of vinyl-pendant octasiloxane (Q8M8V) cubic molecules was included into the Nafion® matrix during the recasting process and then subjected to polymerization, a nonrandom matrix was obtained. This paper provides an insight into the matrix-formatting role of rigid poly(Q8M8V) blocks, generated in situ in Nafion® matrix, according to thermal analyses (thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA) and Differential Scanning Calorimetry (DSC)) and electron microscopic images of the resulting composite matrix. The P(Q8M8V) played a role in restricting random extensions of proton-conducting channels (PCCs) and promoted ordered assembling of Nafion® molecules. As a result, compared with the recast pristine Nafion® membrane, the composite membranes containing P(Q8M8V) of 5–15 wt.% manifested obvious improvement on both repression of methanol permeability and promotion of power density output of the single direct methanol fuel cell (DMFC).
SourceAvailable from: Surya Subianto[Show abstract] [Hide abstract]
ABSTRACT: Layered zirconium phosphate (ZP) that bears fluorinated alkyl chains bonded covalently to the layers (ZPR) was used as a nanofiller in membranes based on a short-side-chain perfluorosulfonic acid (PFSA) to mechanically reinforce the PFSA hydrophobic component. Compared to the pristine PFSA, membranes with a ZPR loading up to 30 wt % show enhanced mechanical properties, and the largest improvement of elastic modulus (E) and yield stress (σY) are observed for the 10 wt % ZPR membrane: ΔE/E up to 90 % and ΔσY/σY up 70 % at 70 °C and 80 % relative humidity (RH). In the RH range 50–95 %, the in-plane conductivity of the composite membranes reaches 0.43 S cm−1 for 10 wt % ZPR at 110 °C and is on average 30 % higher than the conductivity of the pristine PFSA. The 10 wt % ZPR membrane is as hydrated as the neat PFSA membrane at 50 % RH but becomes progressively less hydrated with increasing RH both at 80 and 110 °C. The fuel cell performance of this membrane, at 80 °C and 30 % RH, is better than that of the unmodified PFSA.ChemSusChem 08/2014; 7(8). DOI:10.1002/cssc.201402209 · 7.12 Impact Factor
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ABSTRACT: Nanosized alpha-layered monohydrogen zirconium phosphate (ZP) has been organically modified by reacting the monohydrogen phosphate groups with of 1,2 epoxydodecane solutions in tetrahydrofuran. The materials thus obtained (ZP(C-12)(x) with x in the range 0.74-2.1) have been characterized by TEM, thermogravimetric analysis, X-ray powder diffraction and solid state C-13 CPMAS NMR. The functionalization leads to a disordered layer packing without substantial alteration of the inorganic framework of the alpha-layer of pristine ZP. Samples with x=0.74 and 1.15 have been used as fillers of membranes based on a recast short side chain perfluorinated ionomer with EW=830. Composite membranes with 5-15 wt% filler loadings have been characterized by stress-strain mechanical tests, proton conductivity measurements and water uptake determinations under controlled conditions of temperature and relative humidity (RH). The presence of the filler results in a significant increase in the Young's modulus of the neat ionomer up to a maximum of 55% and 67% at room temperature and at 80 degrees C/70% RH, respectively. AL 100 degrees C and in the RH range 50-90%, the conductivity of the composite membranes is higher than that of the neat ionomer, and the proportional increase in conductivity (72% for RH=50% and +32% for RH=90%) is maximum for 10 wt% tiller loading. Surprisingly, under the same conditions of temperature and RH, the hydration of the most conductive composite membrane is lower than the hydration of the neat ionomer.Journal of Membrane Science 07/2014; 462:42–49. DOI:10.1016/j.memsci.2014.03.021 · 4.91 Impact Factor
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ABSTRACT: In this paper, we provide a highly efficient, convenient and universal protocol for blood-compatible modification of polyethersulfone (PES) membranes via in situ cross-linked copolymerization of 2-hydroxyethl methacrylate (HEMA) and acrylic acid (AA) in PES solutions. Static water contact angle, protein adsorption, platelet adhesion, and clotting time of the modified PES membranes are systematically studied, and the results indicate that the modified membranes show improved hydrophilicity, good blood anticoagulant and antifouling properties after introducing HEMA and AA. Meanwhile, the modified membranes perform low contact activation and complement activation when they come in contact with blood. The effect of the HEMA/AA ratios on the blood compatibility is also investigated to identify the different roles played by HEMA and AA in the modification; the HEMA could more effectively enhance the membrane antifouling property, while the AA could more effectively improve the anticoagulant property. The results indicated that the blood-compatible PES membranes prepared via the in situ cross-linked copolymerization had potential to be used in the field of blood purification.Journal of Membrane Science 10/2014; 468:172–183. DOI:10.1016/j.memsci.2014.06.006 · 4.91 Impact Factor