Abstract: Hydrophobically modified polyacrylamide with hydrophobic microblocks was prepared by homo-copolymerization of sodium 2-acrylamido-tetradecane sulfonate (NaAMC14S) and acrylamide (AM) in water, and cationic Gemini surfactant hexylene-1,6-bis(dodeccyldimethylammonium bromide) (C12C6C12Br2) was synthesized. Apparent viscosity measurement and fluorescence probe methods were used to study the interaction between copolymer NaAMC14S/AM and Gemini surfactant C12C6C12Br2. The experiment results showed that the interaction was strong and exhibited in several aspects as follows: addition of C12C6C12Br2 enabled the copolymer NaAMC14S/AM to produce intermolecular association below its critical association concentration in the absence of C12C6C12Br2; the mixed micells of NaAMC14S/AM and C12C6C12Br2 formed below the critical micellar concentration of C12C6C12Br2; for the aqueous solution of 0.30%(w) copolymer NaAMC14S/AM, the apparent viscosity increased dramatically with the increase of C12C6C12Br2 concentration, and the maximum value of the viscosity was enhanced three orders of magnitude higher than the initial value without C12C6C12Br2. It was found that the interaction between copolymer NaAMC14S/AM and C12C6C12Br2 was dependent on the microstructure of copolymer NaAMC14S/AM, and the greater the content of hydrophobic microblocks, the stronger the interaction and the greater the enhanced magnitude of viscosity.

Key words: Surface-active monomer, Hydrophobically polyacrylamide, Gemini surfactant, Hydrophobic interaction, Mixed micelle