Effects of sequence structure and CO2 absorption on the interface properties and flotation performance of acrylate-DPM copolymer

For the treatment of produced water from offshore oilfields, flotation is an essential process. In recent years, there has been an increase in the amount of produced water, resulting in the need of efficient flotation agents. Recent studies show that amphiphilic polymers perform well in oil removal by flotation, but current researches focus more on the influence of monomer type rather than that of copolymer sequence structure on the oil removal performance. In this study, acrylate and N-(3-dimethylaminopropyl) methacrylamide (DPM) were used as monomers to synthesize copolymers with different sequence structures via free radical polymerization and reversible addition-fragmentation chain transfer polymerization (RAFT). The effects of copolymer sequence structure and CO 2 absorption on the interfacial properties and flotation performance of the copolymer were investigated, meanwhile, the effect of CO 2 absorption on the flotation performance was explained by using molecular dynamics (MD) simulation. It was found that the flotation performance of random copolymers was close to that of diblock copolymers, while triblock copolymers had much better flotation performance. Especially, the ethyl acrylate-DPM-ethyl acrylate triblock copolymer (EDE) with hydrophobic groups on the outside and hydrophilic groups in the center had the best flotation performance, with a turbidity reduction rate of 95.4 %. After CO 2 absorption, the flotation performance of most copolymers decreased, while the flotation performance of triblock copolymers with hydrophilic groups on the outside and hydrophobic groups in the center increased. The MD simulation results showed that the introduction of CO 2 into DPM-ethyl acrylate-DPM triblock copolymer (DED) increased the extensibility of copolymer chain, which was helpful for the flotation. This study provides some theoretical guidance for the microstructural design of flotation agent and presents a new possibility for the reuse of CO 2 .