Nanosized α-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(C12)x, with x in the range 0.74-2.1) have been characterized by TEM, thermogravimetric analysis, X-ray powder diffraction and solid state 13C CPMAS NMR. The functionalization leads to a disordered layer packing without substantial alteration of the inorganic framework of the α-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 5-15wt% 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[U+05F3]s modulus of the neat ionomer up to a maximum of 55% and 67% at room temperature and at 80°C/70% RH, respectively. At 100°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 10wt% filler 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.

Layered zirconium alkylphosphates: Suitable materials for novel PFSA composite membranes with improved proton conductivity and mechanical stability

DONNADIO, Anna;PICA, Monica;CASCIOLA, Mario
2014

Abstract

Nanosized α-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(C12)x, with x in the range 0.74-2.1) have been characterized by TEM, thermogravimetric analysis, X-ray powder diffraction and solid state 13C CPMAS NMR. The functionalization leads to a disordered layer packing without substantial alteration of the inorganic framework of the α-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 5-15wt% 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[U+05F3]s modulus of the neat ionomer up to a maximum of 55% and 67% at room temperature and at 80°C/70% RH, respectively. At 100°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 10wt% filler 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.
2014
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11391/1221296
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