Molecular interaction of poly (acrylamide-co-2-acrylamido-dodecyl sulfonate) with dual responsiveness and application in oily emulsion wastewater

Stimuli-sensitive polymers are a class of macromolecular system with intelligent behavior. Herein, a copolymer of poly (acrylamide-co-2-acrylamido-dodecyl sulfonate), which has salt-sensitive and thermosensitive properties, is synthesized via precipitation polymerization. Its aqueous solution exhibits a clear sol state, while a gel is obtained via salt-induction by addition a certain amount of NaCl. More interestingly, the gel can transform into clear sol again upon heating, which exhibits a phase transition of upper critical solution temperature in NaCl solution. The dual responsive behaviors of copolymer solutions are studied via rheological measurements. Then fluorescence spectrum, zeta potential test, and dynamic light scattering are employed to investigate molecular interaction in aqueous solution under varying conditions. It is found that dual responsive behaviors are caused by electrostatic interaction and hydrophobic association. At last, oily emulsion wastewater treatment indicates that this polymer shows characteristics of smart flocculant and has potential application prospect.

Automated summary

Stimuli-sensitive polymers synthesized via precipitation polymerization exhibit salt-sensitive and thermosensitive properties, displaying dual responsive behaviors in NaCl solution. The interaction between molecules in aqueous solution under varying conditions is found to be caused by electrostatic interaction and hydrophobic association, leading to the smart and potential application prospect of the polymer.