Synthesis and Properties of Novel Proton-Conducting Aromatic Poly(ether sulfone)s That Contain Triazine Groups

Abstract

A series of novel fully aromatic poly(arylene ether sulfone)s that contain 1,3,5-s-triazine groups were synthesized by the reaction of triazine-containing bisphenols with bis(4-fluorophenylsulfone) to study the effects of branching groups on solubility as well as thermal and mechanical properties. Polymers had inherent viscosities from 0.43 to 1.10 dL/g, thermal stabilities >500 °C in air, glass transition temperatures from 136 to 289 °C, and good film forming abilities. The polymer with pendant diphenylamine groups on the triazine ring were further investigated for use in proton exchange membranes based on solubility, thermo-oxidative stability, and ease of monomer synthesis. A series of copolymers made from 4,6-bis(4-hydroxyphenyl)-N,N-diphenyl-1,3,5-triazin-2-amine and 4,4′-biphenol were sulfonated with chlorosulfonic acid to achieve ion exchange capacities up to 2.62 mmol/g. The homopolymer was sulfonated exclusively on the diphenylamine branch and had the highest proton conductivity (0.11 S/cm at 95 °C and 100% relative humidity), even though it had the lowest water uptake and ion exchange capacity. Unsulfonated polymers and sulfonated copolymers showed little uptake of phosphoric acid. However, the sulfonated homopolymer with pendant diphenylamine groups had a 200-250 wt % uptake when soaked in 85% H 3 PO 4 at 90 °C, but the proton conductivity of this polymer was lower than the hydrated polymer without H 3 PO 4 added.

Durability of Sulfonated Aromatic Polymers for Proton‐Exchange‐Membrane Fuel Cells

“…Therefore, to better tailor the properties of SAPs and to understand the relationship between structure and properties, many new SAPs were designed and synthesized through aromatic nucleophilic polycondensation reactions of sulfonated monomers. [50,51] The distribution of electron density in the macromolecule plays an important role in the stability of the polymer. The electron-deficient state can deactivate the aromatic ring, prevent electrophilic attack, and improve its resistance to oxidation and high temperatures.…”

Triazine‐containing benzoxazine and its high‐performance polymer

“…It is well‐known that the activation energy of thermal degradation of triazine ring is much higher than that of benzene ring,4 and the triazine resin has excellent properties such as thermal stability, flame retardance, low dielectric content, and optoelectronic property 5–10. Therefore, the incorporation of a triazine structure into polybenzoxazine will enhance its heat‐resistant and flame‐retardant properties.…”

Synthesis and study of polycyanurates based on 2-carbazol-4,6-dichloro-s-triazine

“…Polymers containing an s-triazine ring in their main chain have certain properties, including high resistance to heat and chemical attack, good mechanical and dielectric properties and an ability to be easily processed. 2 In addition, they are generally infusible and insoluble. Various polycyanurates are used in structural composites with glass or carbon fibers, in casting resins and binders for miscellaneous organic and inorganic substrates, as stabilizers for plastics or as films, fibers or lacquer components.…”