Proton conductivity of poly(dipropyl)phosphazene-sulfonated poly[(hydroxy)propyl, phenyl]ether–H3PO4 composite in dry environment

A new composite material was fabricated by heat pressing a powder mix containing a sulfonated poly[(hydroxy)propyl, phenyl]ether (SPHPE), with empirical formula [–O–Ar–C(Me)2–Ar(SO3H)0.4–O–CH2CH(OH)–CH2–•1.5 H2O]n, and poly(dipropyl)phosphazene (PDPrP) to yield a film which was soaked in 85% H3PO4 (PA) and dried. The final SPHPE–PDPrP–PA film (0.15 cm thick) contained –SO3H functional groups and H3PO4 at 0.16 SO3H / N and 1.72 H3PO4 / N mole ratios. For the phosphazene polymer, at least two types of repeating units were present, i.e., –P(CH2CH2CH3)2 = N– and –P(CH2CH2CH3)2 = NH+(H2PO4−•H3PO4)– at 0.18 N / NH+ mole ratio. This material exhibited proton conductivity (σ, Ω− 1 cm− 1) of 2.27 10− 4–7.10 10− 3 at 24–127 °C in dry environment, and of 4.79 10− 4–1.54 10− 3 at 45–65 °C and 11% relative humidity. The results for SPHPE–PDPrP–PA composite are discussed by comparison to available literature data for other composites and polymers containing N protonated by H3PO4.