Structure, properties and proton conductivity of [formula omitted] nanocomposite membranes

Abstract

In this report are presented the preparation and the characterization of six nanocomposite membranes of formula { Nafion / [ ( Ti O 2 ) ⋅ ( W O 3 ) 0.148 ] ψ Ti O 2 } with ψ Ti O 2 in the range 0–2.988. These materials are based on Nafion and [(TiO 2)·(WO 3) 0.148] nanofiller. The effect of [(TiO 2)·(WO 3) 0.148] nanopowders on the structural, thermal, mechanical and electrical properties of { Nafion / [ ( Ti O 2 ) ⋅ ( W O 3 ) 0.148 ] ψ Ti O 2 } membranes was studied. The water uptake (WU) value of materials was lower than that of pristine Nafion and was correlated with ψ Ti O 2 . The thermal transitions were investigated by modulated differential scanning calorimetry (MDSC). The mechanical parameters and relaxation processes on temperature were studied by dynamical mechanical analyses (DMA). The FT-IR ATR and μ-Raman vibrational investigations allowed to determine the structure of the hydrophobic polytetrafluoroethylene (PTFE) domains of Nafion and the interactions Nafion–[(TiO 2)·(WO 3) 0.148] and Nafion–[H 2O] in bulk materials. The analysis of complex conductivity plots were evaluated in the 10 −2 Hz–10 MHz and 5–155 °C regions. Results indicated that the conductivity of { Nafion / [ ( Ti O 2 ) ⋅ ( W O 3 ) 0.148 ] ψ Ti O 2 } nanocomposite membrane, with ψ Ti O 2 = 1.616 , at 135 °C, is 5.0 × 10 −2 S cm −1, while its stability range of conductivity (SRC) extends up to 135 °C.