The polymerizability of micelle-forming quaternary ammonium monomers, which were derived from a methacrylic ester and styrene, carrying a polymerizable double bond close to the head group (Type H) or at the alkyl chain end (Type T) including a new monomer, 5-(p-vinylphenyl)pentyltrimethylammonium bromide, has been investigated above their critical micelle concentrations in water. The results are explained on the basis of the structure of the obtained polymers as well as the micelle structure of the monomers in water. The Type H monomers were able to thermally polymerize, while the Type T monomers could not.