Coacervation of Cationic Gemini Surfactant with Weakly Charged Anionic Polyacrylamide

Coacervation of cationic gemini surfactant hexamethylene-1,6-bis(dodecyldimethylammonium bromide) (C12C6C12Br2) with 10% hydrolyzed polyacrylamide (PAM) has been observed and investigated by turbidity titration, isothermal titration calorimetry, dynamic light scattering and microscopy. Without any assistant additive, the coacervation takes place at very low surfactant concentration, and exists in a broad surfactant concentration range. The morphology of the coacervate sponge phase varies in pore size as a function of C12C6C12Br2 concentration. The polymer/surfactant aggregates grow from Soluble complexes with sizes smaller than 20 nm to micrometer during coacervation, and break up into soluble complexes of about 40 nm after coacervate redissolution.