Synthesis, characterization, rheological properties of β-cyclodextrin-modified polyacrylamide

Abstract

X-β-cyclodextrin (β-CD), a vinyl-functionalized monomer, was successfully synthesized through the chemical modification of β-CD. Subsequently, X-β-CD was co-polymerized with acrylic acid, acrylamide, and 2-acrylamido-2-methylpropane sulfonic acid via free radical copolymerization to produce a novel hydrophobic inclusion polymer—X-β-HPAM. The structure of X-β-HPAM was characterized using Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and scanning electron microscopy. Furthermore, its aqueous rheological properties were analyzed through rheometry. The results revealed that at shearing temperatures of 120 °C and 150 °C and a shear rate of 170 s⁻¹, the viscosity of a 0.4% X-β-HPAM aqueous solution gradually increased beyond a shear time of 1200 s, indicating the thickening effect of the X-β-CD monomer on the solution at elevated temperatures. Following shearing for 2 h, the residual viscosity stabilized at 62.24 mPa·s, after undergoing a shearing process for a duration of 2 h, the viscosity of a X-β-HPAM salt solution, with a mass fraction of 0.4% and dissolved in a 5% NaCl aqueous solution at a temperature of 150℃, remains consistently stable at the value of 60.04 mPa·s, demonstrating the excellent salt, temperature, and shear resistance of X-β-HPAM. Thus, β-CD-modified polyacrylamide enhances the thermal resistance and shear resistance of fracturing fluids, thereby improving recovery efficiency.

Graphical abstract