A variety of N,N-diallyl compounds, capable of undergoing cyclopolymerization, are prepared from 1,12-dodecanediamine. Selective monoformylation followed by allylation of the parent diamine afforded N,N-diallyl-N'-formyl-1,12-dodecanediamine which was converted into quaternary ammonium monomers N,N-diallyl-N-benzyl (or p-methoxybenzyl)-N'-formyl-1,12-dodecanediamine by reacting with benzyl- or p-methoxybenzyl chloride. The monomers on homo- and co-cyclopolymerization (with SO2) afforded the cationic polyelectrolytes which on acidic hydrolysis of the formyl group gave water-soluble polyelctrolytes. All the synthesized monomers, polymers, and the starting 1,12-dodecanediamine were used to study the corrosion inhibition of mild steel by gravimetry and electrochemical methods in acidic and saline media at 60 degrees C. The inhibitor molecules (at a concentration of 400 ppm) exhibited inhibition efficiencies (%IE) in the ranges 62%99% in 1 M HCl, 95%99% in 4 M HCl, 13%91% in 7.7 M HCl, 13%91% in 0.5 M H2SO4, and 75%90% in 3.5% NaCl. There is a dramatic increase in the IEs by the monomers and polymers in comparison to the parent diamine. POLYM. ENG. SCI., 52:2588-2596, 2012. (C) 2012 Society of Plastics Engineers