Tungstovanadophosphoric heteropoly acid H 6 PW 9 V 3 O 40 •(13.81 ± 0.13)H 2 O (abbreviated as PW 9 V 3 ) has been synthesized by the stepwise acidification and the stepwise addition of element solutions. The crystal structure was determined from single crystal X-ray diffraction. The complex crystallizes in the space group R3̅ m, with a = 16.4374 (9) Å, b = 16.4374 (9) Å, c = 25.3866 ( 14) Å, α = 90°, β = 90°, γ = 120°, V = 5940.20 Å, and Z = 6. The product possesses Keggin structure, and its conductivity was 1.730 × 10 −2 S•cm −1 at 26 °C and 75% relative humidity by electrochemical impedance spectroscopy (EIS) measurement. Two conducting systems were prepared with a mixture of as-synthesized PW 9 V 3 and organic polymers [polyvinylpyrrolidone (PVP) or polyethylene glycol (PEG)] at the weight ratio 80:20. The hybrid materials exhibit high proton conductivities with 7.110 × 10 −3 and 1.050 × 10 −2 S•cm −1 (PW 9 V 3 /PEG) at 26 °C and 75% relative humidity, respectively. Their activation energies of proton conduction are 15.23 and 13.67 kJ•mol −1 , which are lower than that of pristine heteropoly acid (25.68 kJ•mol −1 ). Their mechanisms of proton conduction are also proposed.

A series of reversible phase transformation ammonium- and phosphonium-based polyoxometalate ionic liquid (POM-IL) gels were synthesized and studied with a focus on the correlation between their physicochemical properties and their chemical structure. The products were successfully characterized by IR, UV, XRD and TG-DTA, and their ionic conductivities were measured. The Keggin-type heteropolyanion clusters decorated with long alkyl chains demonstrated a tendency to exhibit a gel state at room temperature, while all the gels transformed into liquids after heating and then recovered after cooling. With a decrease in the alkyl chain length, a significant improvement in the thermal stability and conductivity of the ammonium-based POM-IL gels can be achieved. Moreover, compared with the corresponding ammonium compound, phosphonium-based POM-IL gel was found to be more stable at high temperature and exhibited better conductivity.

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In this article, novel proton-conducting composite membranes SPEEK/PW 11 V and PVA/SiW 11 V were synthesized from vanadium substituted heteropoly acids (H 4 PW 11 VO 40 Á8H 2 O and H 5 SiW 11 VO 40 Á15H 2 O, abbreviated as PW 11 V and SiW 11 V) and polymers (SPEEK or PVA) at the weight ratio 70 : 30. The membranes were characterized by the infrared spectroscopy, X-ray powder diffraction, and scanning electron microscopy, which confirmed the maintenance of the Keggin framework and dispersion homogeneously in the polymer matrix without long-range ordering. Their proton-conducting properties were investigated with electrochemical impedance spectroscopy. The results show that the respective proton conductivities of SPEEK/PW 11 V and PVA/SiW 11 V membranes were in the order of 10 22 and 10 24 S cm 21 at ambient temperature. The temperature dependence of the two composite membrane electrolytes exhibit Arrhenius behavior, and the observed activation energies to be 15.82 kJ mol 21 for SPEEK/PW 11 V and 14.40 kJ mol 21 for PVA/SiW 11 V, which indicates that the proton conduction complies with the Grotthuss mechanism. V C 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42204.

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