Hydrophobic association (HA) hydrogels with outstanding mechanical, rheological and recovery properties were successfully synthesized by micellar copolymerization of acrylamide with lauryl methacrylate. The synthesis occurred at room temperature and the synthesis condition was moderate by using the redox initiator system of Ammonium persulfate ‐ sodium bisulfite as initiators. Cationic surfactant (dodecyl trimethyl ammonium bromide) was utilized to form micelles with hydrophobe, served as physical cross‐linking points in the 3D networks of hydrogels. The HA hydrogels showed a high tensile strength of 181 kPa, superior stretchability of 2300% and excellent toughness of 2.16 MJ m−3. Moreover, they owned extraordinary self‐recovery under different conditions. It is hopeful that the hydrogels with superior mechanical strength and self‐healing properties would be applied to the fields of biomedicine and engineering. Meanwhile, based on above materials, HA hydrogels could also be synthesized with the combination of hydrophobic association and other synergistic effects, such as latex particles, electrostatic effect and nanoparticles.
Aiming at the lack of plugging agent for oil‐based drilling fluid leakage in fractured formation, an oil‐based gel‐plugging agent with high structural strength and strong thermal stability was synthesized based on monomer polymerization and crosslinking. According to the preparation experiment, when the total concentration of methyl methacrylate (MMA) and butyl acrylate (BA) is 30% and the ratio is 6:4, the oil‐based gel solution can be completely gelatinized from 80 to 200°C, which has high gel strength and controllable gelation time. The effects of total concentration of BA and MMA, the ratio of BA and MMA, synthesis temperature, oil‐based drilling fluid invasion, shear effect, and fiber concentration on gelling performance were systematically studied. Fourier transform infrared molecular structure analysis showed that the oil‐based gel contained benzene ring group and ester characteristic group. From the rheological properties of oil‐based gel with 30% gelling agent at 160°C, it could be seen that the elastic modulus G′ of 10 Hz is 232 kPa, which is much larger than the storage modulus G″ is 99 kPa, which reflects the solid properties and has good elasticity and high strength. The displacement experiment of sand filling pipe and dynamic and static plugging experiment of high temperature and high pressure shows that the oil‐based gel has high bearing capacity in fractures and sand filling pipe. The bearing pressure is 3.01 MPa in 6 mm fractures, and the bearing pressure gradient is 0.602 MPa/cm.
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