Interaction of cationic surfactants with acrylic acid ethyl methacrylate copolymers

The aggregation of alkyltrimethylammonium surfactants in the presence of several poly(acrylic acid-co-ethyl methacrylate) copolymers has been studied using pyrene as a probe. The charges on the chain assist the formation of the micelle-like aggregates due the onset of electrostatic interactions, lowering the critical micelle concentration by a factor similar to 20. The increase in the proportion of nonionic monomers lowers the critical aggregation concentration even more, due to the higher hydrophobic character of the polymer chain. The aggregation number for decyltrimethylammonium bromide (DeTAB) also decreases by a factor 3 when going from PAA to the copolymer with 25% of nonionic monomer.