TECHNOLOGY FOCUS - POLYMERS - Preparation (Disclosed): Preparation of the compound (C1) involves providing polybenzimidazole (PBI) having imidazole nitrogens, reacting the PBI with a compound containing a carbonyl group, and substituting at least a portion of the imidazole nitrogens with a moiety from the compound. Preferred Compounds: In the compound (C1), all of the imidazole nitrogens are substituted with the carbonyl-containing moiety, where the carbonyl-containing moiety comprises RCO- (preferably (CH3)2CHCH2OCO-, CH3CH2OCO-, or BrCH2(CH2)3CO-, especially BrCH2(CH2)3CO-). In the compound (C1), the substituted imidazole nitrogens are bonded to the carbon of the RCO- moiety carbonyl group, and R is bonded to the carbon of the carbonyl group by other than a C-O bond. In the compound (C1), R is bonded to the carbon of the carbonyl group by a C-C bond. The compound (C1) is substituted poly-2,2'(meta-phenylene)-5,5'-bibenzimidazole.R=organic and optionally contains an inorganic component (preferably alkoxy, haloalkyl, alkyl, aryl, alkenyl, or alkynyl and the inorganic component comprises oxygen, nitrogen, scandium, yttrium, titanium, zirconium, hafnium, vanadium, niobium, molybdenum, tungsten, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, boron, aluminum, gallium, indium, silicon, germanium, tin, phosphorus, arsenic, antimony, sulfur, selenium, tellurium, or its oxides, especially haloalkyl). EXAMPLE - A cooled parent polybenzimidazole (PBI) solution (32 ml, 0.0013 mol of the polymer repeating unit, each having two reactive N-H sites) was filtered and transferred into round bottom flask equipped with a gas inlet adapter and magnetic stir bar and charged with nitrogen. Then, NaH (80% in oil dispersion) (180 mg) was directly added to the PBI solution and stirred for 6 hours at room temperature. After most of the NaH was consumed, a substitution compound containing a carbonyl group ((CH3)2CHCH2OCOCl, 15 equivalents per N-H site, 5 ml) was added via syringe to the flask. This solution was stirred for 48 hours at room temperature. Upon completion, the reaction solution was transferred directly into a beaker filled with de-ionized, nanopure water (1200 ml). The water-polymer solution was mixed well and filtered through fluted filter paper. The collected polymer was transferred to a crystallizing dish to air-dry overnight. The next day, the dry polymer was dissolved in tetrahydrofuran (THF) (50-150 ml). Sonication was used to disperse and affect dissolution of the polymer in the solution. This THF solution was filtered through fluted filter paper. Any collected solids were set aside, and the yellow-brown, polymer-containing THF solution was condensed to a minimal amount. This solution was added drop wise to a beaker filled with hexanes (1000-1200 ml). The hexanes solution was mixed well and the solids were allowed to settle. The hexanes polymer solution was decanted through a paper filter or filtered through a vacuum aspirator equipped with a 5 mu m nylon filter. The polymer was collected from the filter paper and dried under vacuum to obtain substituted PBI compound (yield 95 wt.%). The obtained substituted PBI compound had a molecular weight of 250000 g/mol.