Effect of fumed silica nanoparticles on the proton conductivity of polyimide–phosphoric anhydride membranes

Abstract

A series of aromatic polyimide-phosphoric anhydride composite membranes loaded with fumed silica (FS) nanoparticles were prepared from polyamic acid (PAA). First, the influence of the percentage loading of phosphoric anhydride (PA) on the proton conductivity of polyimide (PI) membranes was studied. The PA-PI film containing 45% of PA showed proton conductivity of 1.31 Â 10 À4 S/cm at 80 C, whereas the conductivity of neat PI films was 1.80 Â 10 À6 S/cm at room temperature. Next, the effects of the FS nanoparticles on the proton conductivity, the mechanical and thermal properties of the formulated PA-PI membranes were studied. Forty-five percent of the PA-PI membrane loaded with 1% FS (45% PA-PI/1% FS) showed an enhanced conductivity of 2.78 Â 10 À4 S/cm at 80 C when compared to the neat 45% PA-PI membrane. The tensile strength of the 45% PA-PI/1% FS nanocomposite membrane was comparable to the Nafion proton conductive membranes. The thermal analysis of 45% PA-PI/1% FS nanocomposite membranes showed that these membranes were thermally stable and suitable for high-temperature applications.

Effect of phosphoric acid molarity on the structural, thermal, mechanical, and electrical properties of polyimide/polyaniline nanocomposites

“…17,24 The amount of energy lost during ionization increases with acid molarity, and this energy loss causes the surrounding polymer chains to become more flexible, which creates a flexible network. 30,31…”

“…17,24 The amount of energy lost during ionization increases with acid molarity, and this energy loss causes the surrounding polymer chains to become more flexible, which creates a flexible network. 30,31 When the frequency is increased, the dielectric constant decreases, this is due to the reduction in polarization (space charge polarization) and could be explained by the tendency of dipoles which will rarely be able to follow the field of variation at higher frequency values. 11,29 (Figure 7).…”