Proton conductivity and structural properties of nanocomposites based on boehmite incorporated poly(vinlyphosphonic acid)

In this work, novel nanocomposite polymer electrolytes bearing boehmite (Bh) cored polyvinylphosphonic acid (PVPA) were successfully produced and characterized. Nanocomposites based on PVPA(Bh)(x) were formed where x is the weight percentage of Bh in the PVPA matrix ranging from 2.5 to 20%. The interaction of host polymer and the additive, thermal properties, morphology as well as proton conductivities of the electrolytes were systematically studied. The reaction between PVPA and Bh was confirmed by Raman spectroscopy (RS) and X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and transmission electron microscopy (TEM). Thermogravimetric analysis (TGA) showed that nanocomposites have thermal stability up to around 200 degrees C. Differential scanning calorimetry (DSC) indicated the shifting of Tg to higher temperatures with rising Bh content. Scanning electron microscopy (SEM) pictures illustrated the wrapping of Bh by PVPA chains forming polymer-coated nanoparticles for both PVPA(Bh)(5) and PVPA(Bh)(10) and nano-platelet formation for PVPA(Bh)(20). In a completely dry state, the proton conductivity of nanocomposite material increased with Bh up to certain content. Anhydrous PVPABh(10) is the optimum combination and conductivity was measured as 0.02 mS/cm at 150 degrees C. The same electrolyte has conductivity of 0.002 S/cm at ambient temperature in hydrated state (RH = 100%).