High ionic exchange capacity polyphenylsulfone (SPPSU) and polyethersulfone (SPES) cross-linked by annealing treatment: Thermal stability, hydration level and mechanical properties

Abstract

a b s t r a c tThermal stability, hydration and mechanical properties of thermally cross-linked sulfonated aromatic polymers (SAP) with high ionic exchange capacity (IEC) were measured and compared to untreated samples. The formation of cross-linking greatly stabilizes sulfonated polyphenylsulfone (SPPSU) in terms of thermal, mechanical, and hydrolytic degradation: it can resist in water even at a temperature of 145• C with improved mechanical properties, while TGA experiments demonstrate that SPPSU membranes are stable well above 200• C. Sulfonated polyethersulfone (SPES) membranes show, instead, a hydrolytic instability.

Cross‐Linking of Sulfonated Poly(ether ether ketone) by Thermal Treatment: How Does the Reaction Occur?

“…Sulfone bridges are decomposed together with the main chain, as shown previously [26]. The amount of sulfonic acid groups decreases with time, as can be easily seen from the integrated mass loss.…”

“…Thermal treatments of SAP membranes cast from dimethylsulfoxide (DMSO) in appropriate conditions improve their mechanical, thermal, and hydrolytic properties [25,26]. For example thermally treated SPEEK membranes can resist in water also at 145°C without significant swelling, having a Young higher modulus than untreated SPEEK, with interesting proton conductivity [27][28][29].…”

Proton Mobility in Sulfonated PolyEtherEtherKetone (SPEEK): Influence of Thermal Crosslinking and Annealing

“…There are several strategies that might be followed to further improve the properties of SAP and find an optimal balance between mechanical stability on the one hand and proton conductivity on the other, including (i) the introduction of a secondary phase for the realization of composite polymers [22][23][24][25], (ii) the formation of covalent cross-linking bonds between macromolecular chains, realized by innovative chemical synthesis [26,27] or by solvothermal treatments [28,29].…”

“…Given the out-of-equilibrium nature of the polymer, the membrane history is thus of fundamental importance for the observed properties and thermal treatments in presence or absence of solvents can change them significantly. The formation of sulfone bridges, cross-linking (XL) SPEEK chains, by a thermal treatment above 150°C in presence of small quantities of residual casting solvent DMSO has been demonstrated by various spectroscopic techniques [29,32]. The formation of covalent cross-links occurs by electrophilic aromatic substitution with formation of SO 2 + electrophiles according to Scheme 1.…”

Composite polymer electrolytes of sulfonated poly-ether-ether-ketone (SPEEK) with organically functionalized TiO2

“…The current materials research explores different fields: blend of polymers, cross-linked membranes, ionic liquids, block-copolymers, and organic/inorganic hybrids [5][6][7][8][9]. Organic/inorganic hybrids can offer opportunities in many areas and not last in the field of fuel cell materials [10].…”