Polyarylene ether sulfone (PAES) polymers

A gel-permeation chromatography (GPC) method for determining the number average molecular weight (Mn) of a poly(arylether sulfone) polymer, (t-PAES) polymer, wherein more than 70% moles of the recurring units are recurring units (Rt) of formula (St):

• -E-Ar1—SO2—[Ar2-(T-Ar3)n—SO2]m—Ar4— (formula St)
• wherein:
• n and m, equal to or different from each other, are independently zero or an integer of 1 to 5;
• each of Ar1, Ar2, Ar3 and Ar4 equal to or different from each other and at each occurrence, is an aromatic moiety;
• T is a bond or a divalent group optionally comprising one or more than one heteroatom;
• E is of formula (Et):
• wherein:
• each of R′, equal to or different from each other, is selected from the group consisting of halogen, alkyl, alkenyl, alkynyl, aryl, ether, thioether, carboxylic acid, ester, amide, imide, alkali or alkaline earth metal sulfonate, alkyl sulfonate, alkali or alkaline earth metal phosphonate, alkyl phosphonate, amine and quaternary ammonium;
• j′ is zero or is an integer from 1 to 4, said (t-PAES) polymer having a number average molecular weight (Mn) ranging from 41,000 to 90,000 and a polydispersity index of less than 4.0, wherein said GPC method comprises (i) dissolving said (t-PAES) polymer at a temperature from 100 to 250° C. in a solvent suitable for GPC providing a polymer solution wherein the concentration of said (t-PAES) polymer in said polymer solution is between 1.0 to 10.0 mg/ml, and (ii) eluting a specimen of said polymer solution in a GPC column using N-methyl-2-pyrrolidone (NMP) containing at least one salt as eluent, at a temperature from 20 to 50° C.