Effect of large spacer on surface activity, thermal, and rheological properties of novel amido-amine cationic gemini surfactants

Three new amido-amine cationic gemini surfactants comprising large spacer groups were synthesized by amidation of carboxylic acids with 3-(dimethylamino)-1-propylamine and subsequent reaction with dibromoalkane. The structures of gemini surfactants were elucidated by NMR, IR, and elemental techniques. Thermogravimetric analysis results showed impressive short-range thermal stability with no structure decomposition up to 260 °C. The structural characterization technique exhibited excellent long-range thermal stability with the survival of original structure of the gemini surfactants after aging them up to 90 °C for ten days. The critical micelle concentration readings were ranged from 0.094 mmol/L to 0.15 mmol/L and the analogous surface tension (γcmc) values were ranged from 34.12 mN/m to 36.47 mN/m. The rheological investigation was done to examine the interactions between cationic polyacrylamide and cationic gemini surfactants. The polymer viscosity and storage modulus were reduced upon addition of gemini surfactants at low shear rate because of charge screening and polymer-surfactant interactions. The gemini surfactants revealed excellent thermal and surface properties and the investigated surfactant-polymer hybrid material found to be an excellent candidate of high-temperature carbonate reservoir in which anionic surfactants are avoided because of high adsorption.