Conductivity modification of proton conducting polymer gel electrolytes containing a weak acid (ortho-hydroxy benzoic acid) with the addition of PMMA and fumed silica

Abstract

Polymer gel electrolytes synthesized by dispersing nano size fumed silica in polymer gel electrolytes containing polymethylmethacrylate (PMMA), orthohydroxy benzoic acid (o-OHBA) and dimethylacetamide (DMA) have been studied by complex impedance spectroscopy, viscosity and pH measurements. The addition of acid, polymer and fumed silica has been found to result in an increase in conductivity and viscosity of gel electrolytes and gels with conductivity higher than the corresponding liquid electrolytes have been obtained. Nano dispersed polymer gel electrolytes show conductivity 2.95 9 10 -4 S cm -1 and viscosity 1.74 9 10 4 cP at 25°C. Two maxima observed in the variation of conductivity of nano dispersed gels with fumed silica concentration have been assigned to the enhanced dissociation of weak acid and the formation of a high conducting interfacial region between fumed silica and gel electrolyte, respectively, which has also been supported by pH and viscosity studies. The small increase in conductivity of nano dispersed gels over the 20-100°C temperature range and its constant value with time is suitable for devices.

Proton conducting gel electrolytes based on polymethylmethacrylate doped with sulfuric acid solutions in N,N-dimethylformamide

“…Similar results were obtained in [28] for gel electrolyte based on (methyl methacrylatemaleic anhydride) copolymer (P(MMA-MAh) with poly(ethylene glycol) monomethyl ether (PEGME) of different molecular weights, as well as for PMMA gels doped with H 3 PO 4 solutions in DMF [23]. At the same time for gel electrolyte based on PMMA and doped with o-hydroxybenzoic acid solution in dimethylacetamide [5] the contrary results were performed. It was shown that with PMMA molecular weight enhancement from 15,000 to 996,000 the conductivity lowering occurred.…”

“…Variety of polymer materials results in a wide range of polymeric matrix components for gel electrolytes synthesis. Various materials such as poly(vinylidene fluoride ) (PVdF) [1][2][3], poly(methyl methacrylate) (PMMA) [3][4][5][6], poly(ethylene glycol) (PEG) [7][8][9], poly(ethylene oxide) (PEO) [3,10,11], poly(glycidyl methacrylate) (PGMA) [12,13] poly(1-vinil-1,2,4-triazole) [14] and others are used as polymeric matrix.…”

“…At the moment PMMA is one of commonly used polymeric materials for synthesis of proton conducting gel electrolytes [3][4][5][6][15][16][17][18] mainly due to its low price. Important criteria of solvent choice for gel synthesis are high permittivity, low viscosity, wide working temperature range and possibility of solvent molecules protonation by proton-donor.…”

Conductivity and intermolecular interactions in proton‐conducting gel electrolytes

“…The results of investigations of PGEs based on poly(methyl methacrylate) (PMMA) or other available polymers doped with solutions of mineral and organic acids in aprotic solvents have been represented in a number of works . To increase the conductivity of gel electrolytes, strong acids, such as sulfuric or hydrochloric acid, can be used as a proton donor .…”

“…A literature review showed that the PGE conductivity can increase or decrease steadily or pass the maximum; this depends on the nature of both the acid and polymer and on their concentrations.…”