Magnetic-driving giant multilayer polyelectrolyte microcapsules for intelligent enhanced oil recovery

With the worldwide energy crisis breaking out, the global demand for petroleum is increasing tremendously. However, it is still a major challenge to improve oil recovery from oil reservoirs in the petroleum industry. Here, the multilayer giant polyelectrolyte microcapsules (PEM), sodium dodecyl benzene sulfonate-Fe3O4 @ (poly-acrylamine hydrochloride/polystyrene sulfonate)3-poly(N-isopropylacrylamide-co-diallyl dimethyl ammonium chloride) (SFe@(PAH/PSS)3-PND), were prepared through electrostatic self-assembly technique. PND was polymerized from N-isopropylacrylamide (NIPAM) and dimethyl diallyl ammonium chloride (DMDAAC). The oil recovery efficiency of the polyelectrolyte microcapsules was all higher than 50 %, and which was significantly increased to over 70 % after heating above the lower critical solution temperature (LCST). Attributed to the temperature-adjusted intelligent mechanisms of the NIPAM molecular in PND, the contraction of NIPAM mo-lecular chains affected with high temperature, coupled with the reduction of microcapsule volume, led to expansion of the pores in the capsule walls, which significantly increased the permeability of SDBS. Meanwhile, oil droplets combined with SDBS were encapsuled with the hydrophobic PND layer based on hydrophobic interaction, part of which entered into amphiphilic phospholipid core layer. Inspired by cellular cytokinesis, the SFe@ (PAH/PSS)3-PND was capable of intelligently capturing and carrying oil droplets driven with magnetism. The oil recovery efficiency of SFe@ (PAH/PSS)3-PND significantly improved and were all more than 78 % after heating above the LCST With magnetron drive, which is much higher than the traditional method. Hence, this work revealed the novel approaches in potential applications for intelligent enhanced oil recovery (EOR) in the petroleum industry.