Synthesis and switchable behavior of a CO2 responsive polymeric surfactant acting as emulsifier

A new kind of CO2 responsive polymeric surfactant (named DEA-SSS) was synthesized by using 2-(diethylamino)ethyl methacrylate (DEA) and sodium styrene sulfonate (SSS) via radical polymerization. The structure and composition of the copolymer were characterized by FT-IR spectrometer, 1HNMR, and elemental analyzer. It was found that the surface and interfacial tension would be much reduced by adding the synthesized surfactant at low concentration. The amphiphilic copolymer could be dispersed in water after bubbling CO2 and precipitated out upon N2 injection. The variation of copolymer solution with and without CO2 adding was also characterized by electric conductivity meter and transmission electron microscopy (TEM). Pickering emulsion of liquid paraffin in water was prepared using the copolymer as the sole emulsifier with high speed stirring. It was demulsified after purging with CO2 and emulsified again by removal of CO2. The nano-emulsion was made using method of phase inversion composition at elevated temperature through mixing the surfactant with Brij30. When the CO2/N2 were bubbled circularly, the size distribution of nano-emulsions would change reversibly.