Preparation and characterization of proton exchange membrane based on polyphosphoric acid modified by PVDF-HFP

A polyphosphoric acid functionalized proton exchange membrane (PEM) was prepared by a ring opening reaction using the epoxycyclohexylethyltrimethoxysilane (EHTMS) and amino trimethylene phosphonic acid (ATMP) as raw materials and was modified by poly(vinylidene fluoride)-hexafluoro propylene (PVDF-HFP). The structure of the membranes was characterized by Fourier transform infrared and scanning electron microscopy. The X-ray photoelectron spectroscopy explores the content of the elements in the membrane related to the ion exchange capacity value. The membranes' properties including water uptake, swelling ratio, proton conductivity, and hydrolysis stability were studied. Performance tests show that when ATMP/EHTMS=1/5, conductivity of the PVDF-HFP modified PEMs increased from 0.83 x 10(-4) Scm(-1) at 20 degrees C to 9.53 x 10(-3) Scm(-1) at 160 degrees C, the swelling ratio of membranes decreased from 2.71% to 2.13%. The results indicate that the introduction of F atoms is beneficial to increase the proton conductivity and the dimensional stability. (c) 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46737.