The Effects of Sulfonated Poly(ether ether ketone) Ion Exchange Preparation Conditions on Membrane Properties

Abstract

A low cost cation exchange membrane to be used in a specific bioelectrochemical system has been developed using poly(ether ether ketone) (PEEK). This material is presented as an alternative to current commercial ion exchange membranes that have been primarily designed for fuel cell applications. To increase the hydrophilicity and ion transport of the PEEK material, charged groups are introduced through sulfonation. The effect of sulfonation and casting conditions on membrane performance has been systematically determined by producing a series of membranes synthesized over an array of reaction and casting conditions. Optimal reaction and casting conditions for producing SPEEK ion exchange membranes with appropriate performance characteristics have been established by this uniquely systematic experimental series. Membrane materials were characterized by ion exchange capacity, water uptake, swelling, potential difference and NMR analysis. Testing this extensive membranes series established that the most appropriate sulfonation conditions were 60 °C for 6 h. For mechanical stability and ease of handling, SPEEK membranes cast from solvent casting concentrations of 15%–25% with a resulting thickness of 30–50 µm were also found to be most suitable from the series of tested casting conditions. Drying conditions did not have any apparent impact on the measured parameters in this study. The conductivity of SPEEK membranes was found to be in the range of 10−3 S cm−1, which is suitable for use as a low cost membrane in the intended bioelectrochemical systems.

Effects of different sulfuric acid etching concentrations on PEEK surface bonding to resin composite

“…The effect of increase concentrations of sulfuric acid etching demonstrated differences in the alteration of PEEK surface. Differences in irregularity of PEEK surfaces after sulfuric acid etching were due to the dissolution of the PEEK matrix by sulfonation reaction [22][23][24][25] . SEM and AFM clearly demonstrated a tendency of increased surface roughness and irregularities of PEEK which correlated to the increased sulfuric acid etching concentrations (Fig.…”

“…Chemical etching from sulfuric acid could improve hydrophilicity of the surface by introducing sulfonic acid group (−SO 3) into the polymer chains of PEEK due to sulfonation reaction 22,23) . The 80, 85, 90 and 98% sulfuric acid etching to PEEK might attribute to the increase in number of functional groups which influence on the increased SBS, while, the 70% sulfuric acid etching did not improve SBS.…”

“…Most studies recommended the use of 98% sulfuric acid to modify chemical and physical surface of PEEK to improve bonding [16][17][18][19][20] . Previous studies revealed that sulfuric acid created sulfonate (−SO 3) groups in the polymer chains of PEEK [22][23][24][25] which chemically cross-linked to methylmethacrylate (MMA) dental adhesives 13,21) . Another study did not found chemical functional groups on PEEK after etching with 98% sulfuric acid for 60 s, but confirmed micromechanical bonding due to penetration of resin tags into pit and porous surface of PEEK 19) .…”

Chitosan-ABS membrane for DMFC: Effect of sulfonation time and mass ratio of chitosan and ABS

“…The lowest IEC values were obtained from chitosan: ABS mass ratio of 80:20 and 60:40 with sulfonation time of 6 hours, which were 1.191 meq/g and 0.583 meq/g, respectively. Compared to Nafion membrane which IEC value up to 0.9 meq/g (15), chitosan: ABS membrane still has considerable IEC value.…”

“…Sulfonation cause the substitution of -SO 3 H ionic group which affects the addition of membrane hydrophilicity properties [15]. Figure 1 shows the relationship between sulfonation times and water uptake values.…”