Thermosensitive Core–Shell Fe₃O₄@poly(N-isopropylacrylamide) Nanogels for Enhanced Oil Recovery

Abstract

An investigation on the application of thermosensitive core−shell Fe 3 O 4 @PNIPAM nanogels in enhanced oil recovery was successfully performed. Here, the unique core−shell architecture was fabricated by conducting the polymerization at the surface of 3-butenoic acid-functionalized Fe 3 O 4 nanoparticles and characterized using X-ray diffraction (XRD), 1 H NMR, vibration sample magnetometer (VSM), and high-resolution transmission electron microscopy (HR-TEM). According to the results, this core−shell structure was beneficial for achieving the desired high viscosity and low nanofluid mobility ratio at high temperatures, which is essential for enhanced oil recovery (EOR) application. The results demonstrated that the nanogels exhibited a unique temperature-dependent flow behavior due to the PNIPAM shell's ability to transform from a hydrated to a dehydrated state above its low critical solution temperature (LCST). At such conditions, the nanogels exhibited a significantly low mobility ratio (M = 0.86), resulting in an even displacement front during EOR and leads to higher oil production. Based on the result obtained from sand pack flooding, about 25.75% of an additional secondary oil recovery could be produced when the nanofluid was injected at a temperature of 45 °C. However, a further increase in the flooding temperature could result in a slight reduction in oil recovery due to the precipitation of some of the severely aggregated nanogels at high temperatures.

Degradable Fe3O4-based nanocomposite for cascade reaction-enhanced anti-tumor therapy

“…35 The complexation between iron oxide and oleic acid can be proven from the appearance of characteristic symmetric ( ν vs ) and asymmetric ( ν as ) of COO − stretches by FTIR analysis. 36 Zhang et al proposed the complex interactions between carboxylate head (COO − ) and Fe atoms in iron oxides could easily be determined by simply calculating the wave number separation (Δ ν ) between ν vs and ν as of COO − , where Δ ν < 110 cm −1 for chelating bidentate, Δ ν = 140–190 cm −1 for bridging bidentate, and Δ ν = 200–300 cm −1 for monodentate interaction. 37 Based on the FTIR results, the calculated Δ ν for Fe 3 O 4 –OA NPs were found to be 97 cm −1 , which revealed that the coordination mode between oleic acid and Fe atoms in Fe 3 O 4 NPs could be classified as chelating bidentate.…”

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“…The magnetic core possesses magnetic field-responsive characteristics, make it possible for microspheres to achieve precise directional movement and aggregation within porous media, reduce oil adhesion to rock surfaces, address the low sweep efficiency caused by heterogeneity, and thus improve oil recovery rates. Khalil et al [17] utilized magnetically responsive Fe3O4 as the core and temperature-responsive PNIPAM as the shell to prepare Fe 3 O 4 @PNIPAM microspheres via reverse-phase microemulsion polymerization. These microspheres exhibited superparamagnetism, allowing rapid recovery and reuse from produced fluid in the presence of a magnetic field.…”

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“…However, among these potential nanoparticles, Fe 3 O 4 nanoparticles have garnered significant interest and are extensively utilized in biomedical and pharmaceutical fields. 104,105 These characteristics contribute to the popularity of superparamagnetic iron oxide nanoparticles (SPIONs), which possess excellent biocompatibility, a high capacity for magnetization, and are relatively easy to prepare and functionalize. They have extensive usage across multiple domains such as magnetic resonance imaging (MRI), blood purification, drug administration, magnetic hyperthermia, in vivo biomarker identification, and cell patterning.…”