“…Both the used reagents and the synthesis procedure are similar to our previous work [ 23 ]. Commercial PBI powder (BETWEEN, Lizenz GMBH Mw = 25,000–40,000 g mol –1 ), poly(vinyl benzyl chloride) (PVBC, 60/40 mixture of 3- and 4-isomers with average molecular weight Mw ~55.000 and Mw ~100.000, respectively, Sigma Aldrich, Merck Life Science S.L.U., Madrid, Spain), N , N -dimethylacetamide (DMAc, 99.5 wt.%, Sigma Aldrich), potassium hydroxide (KOH, 85 wt.%, Sigma Aldrich), ethanol (absolute, Sigma Aldrich), isopropanol (99.8 wt.%, Labbox Labware, Labbox Labware, S.L., Barcelona, Spain) and DABCO (99 wt.%, Sigma Aldrich), were purchased and used as received.…”