Interaction of Oppositely Charged ...

The interaction between oppositely charged polymer-surfactant systems has been studied using surface tension measurements wherein the dependence of interaction phenomenon over the presence of anionic polyelectrolyte sodium carboxymethylcellulose (NaCMC) with variation of tail length of cationic surfactants, cetyltrimethylammonium bromide (CTAB), tetradecyltrimethylammonium bromide (TTAB), and dodecyltrimethylammonium bromide (DTAB) was investigated. It is observed that the cationic surfactants induced cooperative binding with the anionic polyelectrolyte at critical aggregation concentration (cac) and the cac values are considerably lower than the corresponding critical micelle concentration (cmc) for each of the surfactant irrespective of their hydrophobic tail size. The cmc of surfactants were observed at slightly higher surfactant concentration in polyelectrolyte solution than that in pure water. It was found that the surfactants with longer tail size strongly favour the interaction with NaCMC, indicating the dependence of aggregation phenomenon on the tail size of the surfactants.