Synthesis of magneto-thermal biresponsive temperature-sensitive copolymer/inorganic hybrid green nanoemulsifier with tunable LCST behavior and simulation and calculation of LCST transition behavior of its copolymer

In recent years, intelligent nano-emulsifiers have received a lot of attention in oil fields. Here, a temperature-sensitive copolymer layer, P(NIPAM-co-DMAA), has been grafted in situ on the surface of Fe3O4@SiO2 nano-particles using two monomers, N-isopropylacrylamide and N,N-dimethylacrylamide, by a single-electron-transfer living radical polymerization method. In this way, magneto-thermal dual-responsive temperature-sensitive copolymer/inorganic hybrid nanoparticles, Fe3O4@SiO2@P(NIPAM-co-DMAA), whave been successfully pre-pared. The lowest critical solution temperature (LCST) of P(NIPAM-co-DMAA) could be regulated between 39 and 58 degrees C by modulating the ratio of monomers, endowing Fe3O4@SiO2@P(NIPAM-co-DMAA) nanoparticles with a broader response temperature range for use in more applications. We have used density functional theory and molecular dynamics simulation to thoroughly study the LCST transition behavior of the temperature-sensitive copolymer P(NIPAM-co-DMAA) in water. The intelligent Pickering emulsion obtained by using Fe3O4@SiO2@P(NIPAM-co-DMAA) as a solid particle emulsifier can be regulated between "on" (emulsification) and "off" (breakage) states using temperature and magnetic field as trigger switches. A magnetic field allows the samples to be recycled and reused, which is in line with the energy saving concept. Therefore, the present research may find promising applications in enhanced oil recovery, and other industrial fields, and provides useful insight into the LCST transition behavior of temperature-sensitive polymers.