Several 3-alkyl-1-vinylimidazolium bromides differing by the length of the alkyl chain were prepared and polymerized using a free radical route. The behaviour of the obtained homopolymers in aqueous medium was investigated by several physico-chemical methods including viscosimetry, surface tension measurements and fluorescence spectroscopy. These experiments highlighted a strong influence of the length of the pendent alkyl chain on the side-chain aggregation tendency which is a property of such amphiphilic comb polymers. Fluorescence experiments were also conducted on the surface active analogues, in order to compare their behaviour to that of the polymers.