The direct synthesis of structurally well-defined protic polymeric ionic liquid (PIL) with controlled molecular weight and molecular weight distribution is examined using N,N-diethyl-N-(2-methacryloylethyl) ammonium bis(tri-fluoromethylsulfonyl)imide (DEMH-TFSI) as a monomer. Three polymerization methods, namely, atom transfer radical polymerization (ATRP), activators regenerated by electron transfer (ARGET)-ATRP, and organotellurium-mediated living radical polymerization (TERP) are employed in this study. While the polymerization by ATRP is slow and does not reach high monomer conversion that under ARGET-ATRP and TERP proceeds smoothly and affords structurally well-defined poly(DEMH-TFSI)s. TERP is especially efficient for the control and poly(DEMH-TFSI)s with low to high molecular weights ((M)over bar(n) = 49 100-392 500) and narrow molecular weight distributions ((M)over bar(w)/(M)over bar(n) = 1.17-1.46) are obtained. These results represent the first example of synthesis of a structurally well-defined protic, ammonium PIL by direct polymerization of the protic ionic liquid monomer. The polymerization of N,N-diethyl-N-(2-methacryloylethyl)-N-methylammonium bis(trifluoromethylsulfonyl)imide (DEMM-TFSI), which possesses a quaternary ammonium salt, also proceeds in a highly controlled manner under TERP conditions. A diblock copolymer, polystyrene-block-poly(DEMH-TFSI), is also successfully synthesized by TERP. [GRAPHICS] .