Development of a Hydrophobically Associating Polymer with Ultrahigh Shear Recovery Performance Based on the Characteristics of Stronger Association and Lower Molecular Weight

In recent years, polymers used as thickeners in fracturing fluids tend to pursue a higher molecular weight for better thickening performance. However, these polymers experience mechanical degradation under high shear conditions. To improve the adaptability of polymer fracturing fluids to mechanical shear, a novel hydrophobically associating polymer (HALMP) was developed by enhancing the hydrophobic association action (to improve viscosity and elasticity) while decreasing the molecular weight (to avoid shear degradation and ensure solubility) and characterized by 1H NMR and infrared tests. The calculated molecular weight of HALMP from intrinsic viscosity is 150 × 104 g/mol, and it was concluded that there is strong hydrophobic association in polymer solution from the microscopic structure and macroscopic properties by pyrene fluorescence probe technique, viscoelasticity, and thixotropy tests. Meanwhile, the critical association concentration and the aggregation pattern of polymer molecules in solution were investigated. The shear recovery tests and scanning electron microscopy revealed that the polymer solution contains a dynamic physical crosslinking network that can be "healed" by the intermolecular hydrophobic association action after being sheared. The results also show that HALMP exhibits excellent thickening performance even at a high shear rate. These findings not only demonstrate the feasibility of polymer fracturing fluids with strong association and low molecular weight but also offer alternative methods to prepare high-functional polymers.