A copolymer and its use as coating whereby the copolymer comprises a first monomer of the general formula (I)

##STR00001##

and a second monomer of the general formula (II)

##STR00002##

wherein Y is selected from the group consisting of CH.sub.2Z.sub.3, NHCOR.sub.5, CONHR.sub.6, OCOR.sub.7, COOR.sub.8 and OR.sub.9, and where Z.sub.1, Z.sub.2, and Z.sub.3 are selected from the group consisting of fluoro, chloro, bromo, iodo, hydroxyl, toluene-4-sulfonyloxy and methylsulfonyloxy. R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are independently from each other selected from the group consisting of linear or branched C.sub.1-C.sub.30 alkyl, a linear or branched C.sub.2-C.sub.30 alkenyl, a linear or branched C.sub.2-C.sub.30 alkynyl, sulfo, nitro, amino, hydroxy, oligo(C.sub.2 to C.sub.4-alkylene glycol), NHCOR.sub.5, CONHR.sub.6, OCOR.sub.7, COOR.sub.8 and OR. R.sub.5, R.sub.6, R.sub.7, R.sub.8 and R.sub.9 are selected from the group consisting of a linear or branched C.sub.1-C.sub.30 alkyl, a linear or branched C.sub.2-C.sub.30 alkenyl and a linear or branched C.sub.2-C.sub.30 alkynyl.

A novel polyfluorene-based ionomer, an anion exchange membrane, a method for preparing the polyfluorene-based ionomer, and a method for fabricating the anion exchange membrane are proposed. The polyfluorene-based ionomer contains no aryl ether bonds in the polymer backbone and includes piperidinium groups incorporated into the repeating units. The anion exchange membrane is fabricated from the polyfluorene-based ionomer. The anion exchange membrane has good thermal and chemical stability, excellent mechanical properties, and high ion conductivity. Due to these advantages, the anion exchange membrane can be applied as a membrane for an alkaline fuel cell and to a binder for an alkaline fuel cell or water electrolysis.